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2020

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Schulze Patricia S. C., Bett Alexander J., Bivour Martin, Caprioglio Pietro, Gerspacher Fabian M., Kabaklı Özde Ş., Richter Armin, Stolterfoht Martin, Zhang Qinxin, Neher Dieter, Hermle Martin, Hillebrecht Harald, Glunz Stefan W., Goldschmidt Jan Christoph
25.1% High‐Efficient Monolithic Perovskite Silicon Tandem Solar Cell with a High Band Gap Perovskite Absorber
2020 Solar RRL
KurzfassungMonolithic perovskite silicon tandem solar cells can overcome the theoretical efficiency limit of silicon solar cells. This requires an optimum band gap, high quantum efficiency, and high stability of the perovskite. Here, we combine a silicon heterojunction bottom cell with a perovskite top cell with an optimum band gap of 1.68 eV in planar p‐i‐n tandem configuration. Methylammonium‐free FA0.75Cs0.25Pb(I0.8Br0.2)3 perovskite with high Cs‐content is investigated for improved stability. A 10% molarity increase to 1.1 M of the perovskite precursor solution resulted in ∽75 nm thicker absorber layers and 0.7 mA/cm2 higher short‐circuit current density. With the optimized absorber, tandem devices reach a high fill factor of ∽80% and up to 25.1% certified efficiency. The unencapsulated tandem device shows an efficiency improvement of 2.3% (absolute) over five months showing the robustness of the absorber against degradation. Moreover, a photoluminescence quantum yield analysis reveals that with adapted charge transport materials and surface passivation, along with improved anti‐reflection measures, the high band gap perovskite absorber has the potential for 30% tandem efficiency in the near future.
S. Moench, R. Reiner, P. Waltereit, J. Hueckelheim, D. Meder, R. Quay, O. Ambacher, I. Kallfass
A 600V GaN-on-Si Power IC with Integrated Gate Driver, Freewheeling Diode, Temperature and Current Sensors and Auxiliary Devices
2020 11th International Conference on Integrated Power Electronics Systems (CIPS 2020), Seiten: 1 - 6
St. Moench, R. Reiner, P. Waltereit, St. Müller, R. Quay, O. Ambacher, I. Kallfass
A 600V p-GaN Gate HEMT with Intrinsic Freewheeling Schottky-Diode in a GaN Power IC with Bootstrapped Driver and Sensors
2020 32nd International Symposium on Power Semiconductor Devices and ICs (ISPSD), Seiten: 254 - 257
M. Basler, St. Moench, R. Reiner, P. Waltereit, R. Quay, I. Kallfass, O. Ambacher
A GaN-based Current Sense Amplifier for GaN HEMTs with Integrated Current Shunts
2020 32nd International Symposium on Power Semiconductor Devices and ICs (ISPSD), Seiten: 274 - 277
G. Ganzenmüller, F. Balle, S. Beisel, P. Jakkula, A. Trippel, F. Gutmann, K. Hoschke, S. Hiermaier
Additiv gefertigte auxetische Metamaterialien ermöglichen maßgeschneiderte Funktionalität.
2020 Kompass-I, Seiten: 24 - 27
Sato S, Weidlich A
Analysis of Avoided Transmission Through Decentralized Photovoltaic and Battery Storage Systems
2020 IEEE T Sustain Energ, Band: 11, Nummer: 3, Seiten: 1922 - 1929
KurzfassungDecentralized renewable energy systems can be low-carbon power sources, and promoters of local economies. It is often argued that decentralized generation also helps reducing transmission costs, as generation is closer to the load, thus utilizing the transmission system less. The research presented here addresses the question whether or not, or under what circumstances this effect of avoided transmission can actually be seen for a community-operated cluster of photovoltaic (PV) power plants in two sample locations, one in Germany and one in Japan. For the analysis, the newly developed instrument of MPI-MPE diagrams is used, which plot the maximum power import (MPI) and maximum power export (MPE) in relation to the reference case of no local generation. Results reveal that for moderately sized PV systems without battery storage, avoided transmission can be seen in the Japanese model location, but not in Germany. It was also found that an additional battery storage can lead to avoided transmission in both locations, even for large sizes of installed PV capacity.

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Negassi, Misgana,, Suarez-Ibarrola Rodrigo,, Hein Simon,, Miernik Arkadiusz,, Reiterer, Alexander
Application of artificial neural networks for automated analysis of cystoscopic images: a review of the current status and future prospects
2020 World J Urol

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A. Ding, L. Kirste, Y. Lu, R. Driad, N. Kurz, V. Lebedev, T. Christoph, N.M. Feil, R. Lozar, T. Metzger, O. Ambacher, A. Zukauskaite
Enhanced electromechanical coupling in SAW resonators based on sputtered non-polar Al0.77Sc0.23N 11 2 ¯ 0 thin films
2020 Appl Phys Lett, Band: 116, Nummer: 10

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S. Leone, R. Fornari, M. Bosi, V. Montedoro, L. Kirste, P. Doering, F. Benkhelifa, M. Prescher, C. Manz, V. Polyakov, O. Ambacher
Epitaxial growth of GaN/Ga2O3 and Ga2O3/GaN heterostructures for novel high electron mobility transistors
2020 Journal of Crystal Growth, Band: 534

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T. Kemmer, M. Dammann, M. Baeumler, V. Polyakov, P. Brückner, H. Konstanzer, R. Quay, O. Ambacher
Failure Analysis of 100 nm AlGaN/GaN HEMTs Stressed under On-and Off-State Stress
2020 IEEE International Reliability Physics Symposium (IRPS), Seiten: 1 - 6
D. Urban, O. Ambacher, C. Elsässer
First-principles calculation of electroacoustic properties of wurtzite (Al, Sc) N
2020 arXiv:2002.08143
Watson, E, Kunert, N, Putzar, R, Maas, H, Hiermaier S
Four-view split-image fragment tracking in hypervelocity impact experiments
2020 Int J Impact Eng, Nummer: 135
KurzfassungFragmentation is a significant phenomenon caused by hypervelocity impact and has applications in orbital debris and planetary impact research, among many others. In particular, the velocity distribution of fragments created by hypervelocity impact is not thoroughly understood. In this paper, we present an experimental setup and analysis method for tracking and measuring individual fragment velocities in 3D. The setup uses two synchronized high-speed cameras with split images, yielding four views, to record image sequences of the in-flight fragments. We analyze the image sequences by identifying fragments and their trajectories in each view, matching the fragments found in different views, and finally triangulating for their 3D positions. The result is a method able to measure fragments’ 3D velocities in the highly transient hypervelocity process.
Reiterer, A.;, Wäschle, K.;, Störk, D.;, Leydecker, A.;, Gitzen, N.
Fully Automated Segmentation of 2D and 3D Mobile Mapping Data for Reliable Modeling of Surface Structures Using Deep Learning
2020 Remote Sensing
KurzfassungMaintenance and expansion of transport and communications infrastructure requires ongoing construction work on a large scale. To plan and execute these in the best possible way, up-to-date and highly detailed digital maps are needed. For example, until recently, telecommunication companies have performed documentation and mapping of as-built urban structures for construction work manually and with great time expense. Mobile mapping systems offer a solution for documenting urban environments fast and mostly automated. In consequence, large amounts of recorded data emerge in short time, creating the need for automated processing and modeling of these data to provide reliable foundations for digital planning in reasonable time. We present (a) a procedure for fully automated processing of mobile mapping data for digital construction planning in the context of nationwide broadband network expansion and (b) an in-depth study of the performance of this procedure on real-world data. Our multi-stage pipeline segments georeferenced images and fuses segmentations with 3D data, which allows exact localization of surfaces and objects, which can then be passed via interface, e.g., to a geographic information system (GIS). The final system is able to distinguish between similar looking surfaces, such as concrete and asphalt, with a precision between 80% and 95%, regardless of setting or season.

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P. Reinke, F. Benkhelifa, L. Kirste, H. Czap, L. Pinti, V. Zürbig, V. Cimalla, C. Nebel, O. Ambacher
Influence of Different Surface Morphologies on the Performance of High-Voltage, Low-Resistance Diamond Schottky Diodes
2020 IEEE T Electron Dev, Band: 67, Nummer: 6, Seiten: 2471 - 2477
M. Basler, R. Reiner, S. Moench, P. Waltereit, R. Quay, I. Kallfass, O. Ambacher
Large-Area Lateral AlGaN/GaN-on-Si Field-Effect Rectifier with Low Turn-On Voltage
2020 IEEE Electr Device L
F. Staab, M. Liesegang, F. Balle
Local shear strength distribution of ultrasonically welded hybrid Aluminium to CFRP joints
2020 Compos Struct, Band: 248
F.Thome, A.Leuther, O.Ambacher
Low-Loss Millimeter-Wave SPDT Switch MMICs in a Metamorphic HEMT Technology
2020 IEEE Microwave and Wireless Components Letters
KurzfassungF. Thome, A. Leuther, O. Ambacher, Low-Loss Millimeter-Wave SPDT Switch MMICs in a Metamorphic HEMT Technology (2019), IEEE Microwave and Wireless Components Letters. doi: 10.1109/LMWC.2019.2958209
Reichmuth Kasimir, Siefer Gerald, Schachtner Michael, Mühleis Matthias, Hohl-Ebinger Jochen, Glunz Stefan W.
Measurement Uncertainties in I–V Calibration of Multi-junction Solar Cells for Different Solar Simulators and Reference Devices
2020 IEEE J Photovolt, Seiten: 1 - 8
KurzfassungDifferent types of dual-junction solar cells (perovskite/silicon and GaInP/(Al)GaAs) are used in an investigation of measurement uncertainty for electrical characterization of multijunction solar cells. A method traceable to international reference standards is presented. The spectral mismatch factor matrix is introduced and used with a Monte-Carlo method including manifold correlated and uncorrelated uncertainties. In this way, a detailed analysis of the solar simulator’s spectral irradiance and its influence on uncertainty becomes possible. The use of subcelladapted and broadband reference solar cells is addressed regarding their impact on uncertainty. This allows for finding optimal conditions for calibration with lowest measurement uncertainty. The short-circuit current ofa series connected multi-junction solar cell is affected by luminescence coupling and other effects. With an experimental method it is shown how the uncertainty of the device short-circuit current can be precisely determined. The spectrometric characterization method allows deriving uncertainties of all I–V parameters. In this way a complete evaluation of measurement uncertainty for the calibration of multi-junction solar cells at standard testing conditions is introduced. This article is an extension to our work presented at the 46th IEEE PVSC. Here, we have added a detailed analysis of the influence of different solar simulator spectral irradiance distributions on measurement uncertainty by evaluating a Monte Carlo simulation introducing correlation coefficients. In addition for the first time, it is shownhow luminescent coupling influences the calibration of multi-junction solar cells and how the effect needs to be implemented into the uncertainty of measurement for the short-circuit current as well as efficiency.
Ganzenmüller G, Plappert D
Mechanical Properties of a Unidirectional Basalt-Fiber/Epoxy Composite
2020 J. Compos. Sci., Band: 4, Nummer: 3, Seite: 101

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J. Ligl, S. Leone, C. Manz, L. Kirste, P. Doering, T. Fuchs, M. Prescher, O. Ambacher
Metalorganic chemical vapor phase deposition of AlScN/GaN heterostructures
2020 J Appl Phys, Band: 127, Nummer: 19
V.Lebedev, T.Yoshikawa, C.Schreyvogel, L.Kirste, J.Weippert, M.Kunzer, A.Graff, O.Ambacher
Microstructural and optical emission properties of diamond multiply twinned particles
2020 Journal of Applied Physics
M. Basler, S. Moench, R. Reiner, P. Waltereit, R. Quay, I. Kallfass, O. Ambacher
Monolithic Integration of Inductive Components in a GaN-on-Si Technology
2020 11th International Conference on Integrated Power Electronics Systems, Berlin, Seiten: 1 - 6
S.Leone, P.Brueckner, L.Kirste, P.Doering, T.Fuchs, S.Mueller, M.Prescher, R.Quay, O.Ambacher
Optimization of Metal‐Organic Chemical Vapor Deposition Regrown n‐GaN
2020 physica status solidi (b)
Schulze Patricia S.C., Wienands Karl, Bett Alexander J., Rafizadeh Saeid, Mundt Laura E., Cojocaru Ludmila, Hermle Martin, Glunz Stefan W., Hillebrecht Harald, Goldschmidt Jan Christoph
Perovskite hybrid evaporation/ spin coating method: From band gap tuning to thin film deposition on textures
2020 Thin Solid Films, Band: 704, Seite: 137970
KurzfassungMost efficient perovskite solar cells are synthesized by the one-step spin coating method. However, when applied on µm-sized textures, e.g. for efficient monolithic perovskite silicon tandems, no conformal film formation is achieved. In this respect, we investigate hybrid evaporation/ spin coating for mixed cation mixed halide perovskite absorbers [HC(NH2)2]0.83Cs0.17Pb(I1-xBrx)3 (x = 0–0.28). By control of the 2nd deposition step, we demonstrate systematic band gap tuning from 1.54 to 1.75 eV. Moreover, critical criteria for synthesis and underlying charge transport materials (CTM) are determined by investigation of planar as well as scaffolded electron transport layers. Regarding the applicability on textures, the tandem-relevant 1.7 eV high band gap absorber is deposited on planar, pyramidal, and spiky black silicon to investigate crystallization and layer formation dependent on the substrate's topography. We recommend the presented hybrid method for realization of dense crystalline perovskite films with flat surface, deposition on planar CTM, and textured Si-based tandems with random pyramids.
Sang-Won Lee, Soohyun Bae, Jae-Keun Hwang, Wonkyu Lee, Solhee Lee, Ji Yeon Hyun, Kyungjin Cho, Seongtak Kim, Friedemann D. Heinz, Sung Bin Choi, Dongjin Choi, Dongkyun Kang, Jeewoong Yang, Sujeong Jeong, Se Jin Park, Martin C. Schubert, Stefan Glunz, Won Mok Kim, Yoonmook Kang, Hae-Seok Lee, Donghwan Kim
Perovskites fabricated on textured silicon surfaces for tandem solar cells
2020 Communications Chemistry, Band: 3, Nummer: 1
KurzfassungThe silicon surface texture significantly affects the current density and efficiency of perovskite/silicon tandem solar cells. However, only a few studies have explored fabricating perovskite on textured silicon and the effect of texture on perovskite films because of the limitations of solution processes. Here we produce conformal perovskite on textured silicon with a dry two-step conversion process that incorporates lead oxide sputtering and direct contact with methyl ammonium iodide. To separately analyze the influence of each texture structure on perovskite films, patterned texture, high-resolution photoluminescence (μ-PL), and light beam-induced current (μ-LBIC), 3D mapping is used. This work elucidates conformal perovskite on textured surfaces and shows the effects of textured silicon on the perovskite layers with high-resolution 3D mapping. This approach can potentially be applied to any type of layer on any type of substrate.
Hirschburger R, Weidlich A
Profitability of Photovoltaic and Battery Systems on Municipal Buildings
2020 Renew Energ, Band: 153, Seiten: 1163 - 1173
KurzfassungThe increasing gap between electricity prices and feed-in tariffs for photovoltaic (PV) electricity in many countries, along with the recent strong cost degression of batteries, led to a rise in installed combined PV and battery systems worldwide. The load profile of a property greatly affects the self-consumption rate and, thus, the profitability of the system. Therefore, insights from analyses of residential applications, which are well studied, cannot simply be transferred to other types of properties. In comparison to residential applications, PV is especially suitable for municipal buildings, due to their better match of demand and supply. In order to analyze the value of additional batteries, municipal PV battery systems of different sizes were simulated, taking load profiles of 101 properties as inputs. It was found that self-consumption differs significantly from households, while different types of municipal buildings are largely similar in terms of the indicators analyzed. The share of electricity consumed during summertime was found to have the most significant impact on the self-consumption rate for most considered system sizes. Due to lower electricity tariffs and lower increases in self-consumption provided through batteries in municipal buildings, the investment into a battery is not economically advantageous in most of the cases considered.

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Unnewehr J F, Waldl H-P, Pahlke T, Weidlich A
Reducing Operational Costs of Offshore HVDC Energy Export Systems Through Optimized Maintenance
2020 Energies, Band: 13, Nummer: 1146, Seiten: 1 - 20
KurzfassungFor the grid connection of offshore wind farms today, in many cases a high-voltage direct current (HVDC) connection to the shore is implemented. The scheduled maintenance of the offshore and onshore HVDC stations makes up a significant part of the operational costs of the connected wind farms. The main factor for the maintenance cost is the lost income from the missing energy yield (indirect maintenance costs). In this study, we show an in-depth analysis of the used components, maintenance cycles, maintenance work for the on- and offshore station, and the risks assigned in prolonging the maintenance cycle of the modular multilevel converter (MMC). In addition, we investigate the potential to shift the start date of the maintenance work, based on a forecast of the energy generation. Our findings indicate that an optimized maintenance design with respect to the maintenance behavior of an HVDC energy export system can decrease the maintenance-related energy losses (indirect maintenance costs) for an offshore wind farm to almost one half. It was also shown that direct maintenance costs for the MMC (staff costs) have small effect on the total maintenance costs. This can be explained by the fact that the additional costs for maintenance staff are two orders of magnitude lower than the revenue losses during maintenance.

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Oliveira, P, May, M, Panzera, T, Scarpa, F, Hiermaier S
Reinforced biobased adhesive for eco-friendly sandwich panels
2020 Int J Adhes Adhes, Nummer: 98, Seite: 102550
KurzfassungThis work describes the development of a bio-polyurethane (bio-PU) adhesive made from castor oil plant to be used in sustainable (eco-friendly) sandwich panels made from recycled plastic waste. Low-cost fillers, such as Portland cement and recycled rubber particles are incorporated into the biopolymer to modify its mechanical behaviour. Epoxy is also used to benchmark the mechanical performance of the reinforced biopolymer described in this work. A full factorial design is performed to identify the effects of the types of adhesive, particles and their weight fraction on the mechanical and physical properties of hybrid panels. Single lap and adapted T-peel tests are used to assess the adhesion of the polymers to the aluminium surfaces. The inclusion of 3 wt% cement particles in the biopolymer provides a significant increase in the tensile strength and stiffness compared to the pristine bio-PU. Other properties that benefit from that amount of reinforcement in the bio-adhesive are the impact resistance and reduction of density and porosity compared to higher fractions of inclusions. Despite its lower mechanical properties, the biopolymer with rubber particles provides however an increase of the single lap shear strength, the opposite of what happens when using the reinforced epoxy polymer. The T-peel test also highlights the higher bonding affinity of the biopolymer to the sustainable sandwich core; that indicates the promise of using this biopolymer-reinforced adhesive in secondary and sustainable applications.
Pfaff, A., Bierdel, M., Hoschke, K., Wickert, M., Riedel, W., Hiermaier, S.
Resource analysis model and validation for selective laser melting, constituting the potential of lightweight design for material efficiency
2020 Sustainable production and consumption 21, Nummer: 21, Seiten: 182 - 191
KurzfassungSelective Laser Melting (SLM) offers significant potential for a sustainable way of production. Raw material in form of metallic powder can directly be reused and the selective nature of the process offers new potential for resource economization. We introduce a mathematical model, which allows conclusions about the influence of parameters like part volume (influenced by lightweight design) and exposure parameters onto the resource consumption in an SLM process. For this purpose, time and energy consumption are classified in process shares as a function of volume and process parameters. The introduced approach is validated by experimental methods under the consideration of part volume, exposure parameters and batch size. While the approach shall be independent of the manufactured material, the experiments are executed for the aluminum alloy AlSi10Mg. The measurements quantify the impact of the part volume and process parameters on the resource consumption and provide recommendations for improvements regarding an increased material efficiency. Additionally, the established model can be used to analyze manufacturing costs for single parts or series productions. The results illustrate the importance of lightweight design methods for an efficient and sustainable production by powder bed fusion methods like SLM.
R. Reiner, Th. Gerrer, B. Weiss, P. Waltereit, St. Moench, D. Meder, M. Sinnwell, M. Dammann, R. Quay, O. Ambacher
Si-Substrate Removal for AlGaN/GaN Devices on PCB Carriers
2020 32nd International Symposium on Power Semiconductor Devices and ICs (ISPSD), Seiten: 286 - 289
Beinert Andreas J., Imm Mark, Benick Jan, Becker Felix, Seitz Sonja, Heinrich Martin, Paul Oliver, Glunz Stefan W., Aktaa Jarir, Eitner Ulrich, Neuhaus Holger
Silicon solar cell–integrated stress and temperature sensors for photovoltaic modules
2020 Progress in Photovoltaics: Research and Applications
KurzfassungWe propose silicon solar cell–integrated stress and temperature sensors as a new approach for the stress and temperature measurement in photovoltaic (PV) modules. The solar cell–integrated sensors enable a direct and continuous in situ measurement of mechanical stress and temperature of solar cells within PV modules. In this work, we present a proof of concept for stress and temperature sensors on a silicon solar cell wafer. Both sensors were tested in a conventional PV module setup. For the stress sensor, a sensitivity of (−47.41 ± 0.14)%/GPa has been reached, and for the temperature sensor, a sensitivity of (3.557 ± 0.008) × 10−3 K−1 has been reached. These sensors can already be used in research for increased measurement accuracy of the temperature and the mechanical stress in PV modules because of the imple- mentation at the precise location of the solar cells within a laminate stack, for process evaluation, in-situ measurements in reliability tests, and the correlation with realexposure to climates.
Schubert Martin C., Mundt Laura E., Walter Daniel, Fell Andreas, Glunz Stefan W.
Spatially resolved performance analysis for perovskite solar cells
2020 Adv Energy Mater, Seiten: 194001 - 194019
KurzfassungThis review explores the current state of the art in spatially resolved charac-terization of mixed-halide perovskite solar cells. As the size of perovskite cells and modules continues to grow, quantification of the spatial distribution of key cell parameters will become increasingly valuable in predicting ultimate cell-level performance and tracking process homogeneity. Here, both high resolution microscopic approaches using scanning techniques and camera-based methods for full-area cell and/or module analysis are discussed. The value of this local data in predicting performance losses at the cell level is particularly emphasized. Measurable physical parameters sensitive to losses of voltage, current, fill factor, and efficiency are discussed together with selected experi-mental results. It is demonstrated that a combination of spatially resolved cell parameter mapping/imaging can be used to quantitatively discriminate various loss contributions at high resolution. The impact and control of inhomogeneities become particularly important when upscaling from small devices to large formats compatible with industrial mass production.
Hubert Hauser, Kai Mühlbach, Oliver Höhn, Ralph Müller, Sonja Seitz, Jürgen Rühe, Stefan W. Glunz, Benedikt Bläsi
Tailored disorder: a self-organized photonic contact for light trapping in silicon-based tandem solar cells
2020 Opt Express, Band: 28, Nummer: 8, Seite: 10909
KurzfassungWe present a process development leading to efficient rear side light trapping structures with the purpose of enhancing the infrared response of a silicon-based tandem solar cell. To this end, we make use of phase separation effects of two immiscible polymers, polystyrene and poly(methyl methacrylate), resulting in a non-periodic polystyrene structure on silicon with a well-defined size distribution. Onto this pattern, we evaporate silver as a scattering rear side mirror and contact layer. Average feature sizes and periods can be tuned by varying material properties (e.g. molar weights or ratios of the polymers) as well as processing conditions during the spin coating. This way a favorable pseudo period of approx. 1 µm for these disordered structure features was realized and successfully implemented into a silicon solar cell. The structure shows a ring-shaped scattering distribution which is beneficial for light trapping in solar cells. External quantum efficiency measurements show that a gain in short circuit current density of 1.1 mA/cm2 compared to a planar reference can be achieved, which is in the same range as we achieved using nanoimprint lithography in a record triple-junction III/V on a silicon device.
Wilson Gregory M., Al-Jassim Mowafak M., Metzger Wyatt K., Glunz Stefan W., Verlinden Pierre, Gang Xiong, Mansfield Lorelle M., Stanbery Billy J., Zhu Kai, Yan Yanfa, Berry Joseph J., Ptak Aaron J., Dimroth Frank, Kayes Brendan M., Tamboli Adele C., Peibst Robby, Catchpole Kylie R., Reese Matthew, Klinga Christopher, Denholm Paul, Morjaria Mahesh, Deceglie Michael G., Freeman Janine M., Mikofski Mark A., Jordan Dirk C., TamizhMani Govindasamy, Sulas Dana B.
The 2020 Photovoltaic Technologies Roadmap
2020 Journal of Physics D: Applied Physics
KurzfassungOver the past decade, the global cumulative installed photovoltaic (PV) capacity has grown exponentially, reaching 591 GW in 2019. Rapid progress was driven in large part by improvements in solar cell and module efficiencies, reduction in manufacturing costs and the realization of levelized costs of electricity that are now generally less than other energy sources and approaching similar costs with storage included. Given this success, it is a particularly fitting time to assess the state of the photovoltaics field and the technology milestones that must be achieved to maximize future impact and forward momentum. This roadmap outlines the critical areas of development in all of the major PV conversion technologies, advances needed to enable terawatt-scale PV installation, and cross-cutting topics on reliability, characterization, and applications. Each perspective provides a status update, summarizes the limiting immediate and long-term technical challenges and highlights breakthroughs that are needed to address them. In total, this roadmap is intended to guide researchers, funding agencies and industry in identifying the areas of development that will have the most impact on PV technology in the upcoming years.
Harder N, Qussous R, Weidlich A
The cost of providing operational flexibility from distributed energy resources
2020 Appl Energ, Band: 279, Seiten: 1 - 16
KurzfassungFlexible household devices, such as heat pumps combined with thermal energy storage or battery energy storage units, can provide flexibility to the electricity sector. However, to make flexibility available to the market, it has to be correctly quantified, and its cost has to be estimated. In this work, a methodology for generic flexibility quantification is proposed and developed in a Python environment using model predictive control. The chosen methodology allows to quantify the adjustable power, and also to determine the corresponding cost of the flexibility provision. It was observed that the available flexibility and its cost is influenced by many factors such as system components, human behavior, building thermal parameters, and price signals. Also, the inclusion of even a low share of households with batteries or electric vehicles smoothens the aggregated flexibility profile, and a considerable amount of flexibility is available at almost any point in time.

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Schäfer M, Tranberg B, Jones D, Weidlich A
Tracing carbon dioxide emissions in the European electricity markets
2020 Proceedings of the 17th European Energy Market Conference
KurzfassungConsumption-based carbon emission measures aim to account for emissions associated with power transmission from distant regions, as opposed to measures which only consider local power generation. Outlining key differences between two different methodological variants of this approach, we report results on consumption-based emission intensities of power generation for European countries from 2016 to 2019. We find that in particular for well connected smaller countries, the consideration of imports has a significant impact on the attributed emissions. For these countries, implicit methodological choices in the input-output model are reflected in both hourly and average yearly emission measures.

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Koki Suwa, Ludmila Cojocaru, Karl Wienands, Clarissa Hofmann, Patricia Samia Cerian Schulze, Alexander J Bett, Kristina Winkler,, Jan Christoph Goldschmidt, Stefan W Glunz, Hiroyuki Nishide
Vapor-Phase Formation of a Hole-Transporting Thiophene Polymer layer for Evaporated Perovskite Solar Cells
2020 Acs Appl Mater Inter
KurzfassungHomogeneous layer formation on textured silicon substrates is essential for the fabrication of highly efficient monolithic perovskite silicon tandem solar cells. From all well-known techniques for fabrication of perovskite solar cells (PSCs), the evaporation method offers the highest degree of freedom for layer-by-layer deposition independent of the substrate´s roughness or texturing. Hole-transporting polymers with high hole mobility and structural stability have been used as effective hole-transporting materials (HTMs) of PSCs. However, the strong intermolecular interactions of the polymers do not allow for a layer formation via the evaporation method which is a big challenge for the perovskite community. Herein, we firstly applied a hole-transporting terthiophene polymer (PTTh) as a HTM for evaporated PSCs via an in-situ vapor phase polymerization using iodine (I2) as a sublimable oxidative agent.

2019

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Maciej Cwiklinski, Peter Brückner, Stefano Leone, Christian Friesicke, Roger Lozar, Hermann Maßler, Rüdiger Quay, Oliver Ambacher
190-GHz G-band GaN amplifier MMICs with 40GHz of bandwidth
2019 IEEE, Seiten: 1257 - 1260

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A.Dyck, M.Kuri, M.Roesch, A.Tessmann, O.Ambacher
A Dielectric-Filled Cavity-Backed Lens-Coupled Dipole Antenna at 100 GHz
2019 IEEE Radio and Wireless Symposium (RWS), Seiten: 1 - 3
M.Basler, S.Moench, R.Reiner, P.Waltereit, R.Quay, I.Kallfass, O.Ambacher
A GaN-on-Si-Based Logic, Driver and DC-DC Converter Circuit with Closed-Loop Peak Current-Mode Control
2019 PCIM Europe 2019; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Nuremberg, Germany, Seiten: 1 - 6

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M. Basler, S. Moench, R. Reiner, P. Waltereit, R. Quay, I. Kallfass, O. Ambacher
A Pseudo-Complementary GaN-Based Gate Driver with Reduced Static Losses
2019 IEEE, Seiten: 93 - 98

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Ganzenmüller, Georg, Plappert, David, Trippel, Antonina, Hiermaier, Stefan
A Split-Hopkinson Tension Bar study on the dynamic strength of basalt-fibre composites
2019 Compos Part B-eng, Seiten: 310 - 319
KurzfassungThis paper investigates the strain rate sensitivity of laminated composites made of plies of unidirectional basalt fibres and epoxy resin. We consider laminates with quasi-isotropic [0∘,−45∘,+45∘,90∘]s and orthogonal [+45∘,−45∘]4 layup. A Split-Hopkinson Tension Bar is used to generate accurate stress/strain data at elevated rates of strain of ≈3 × 102/s. Moderate strain rate effects are observed with strength increase of ≈3.5% per decade of increased loading rate for both laminate types.
A.Dyck, M.Roesch, A.Tessmann, A.Leuther, M.Kuri, S.Wagner, B.Gashi, J.Schaefer, O.Ambacher
A Transmitter System-in-Package at 300 GHz With an Off-Chip Antenna and GaAs-Based MMICs
2019 IEEE T Thz Sci Techn, Band: 9, Nummer: 3, Seiten: 335 - 344
KurzfassungA. Dyck, M. Rösch, A. Tessmann, A. Leuther, M. Kuri, S.Wagner, B. Gashi, J. Schäfer, O. Ambacher, A Transmitter System-in-Package at 300 GHz With an Off-Chip Antenna and GaAs-Based MMICs (2019) IEEE Transactions on Terahertz Science and Technology 9 (3), pp. 335-344. doi: 10.1109/TTHZ.2019.2910511
Ganzenmüller, Georg, Patil, Sankalp, Maurer, Michael, Sauer, Martin, Jung, Markus, Hiermaier, Stefan
A simple glassy polymer model
2019 Journal of dynamic behavior of materials, Nummer: 3, Seiten: 331 - 343
KurzfassungThis work presents a simple and robust material model, suitable for dynamic simulations of glassy polymers such as Polycarbonate. The new model reduces the complex stress/strain behavior and its dependence on strain rate and temperature to a simple set of characteristics. Utilizing a time–temperature superposition principle, these characteristics serve as input for a purely empirical fitting approach, which provides an accurate representation of the material behaviour over a wide range of strain rates and temperatures. Calibration data including failure at high rates is obtained using a split Hopkinson tension bar. To demonstrate the applicability of the new model, it is parameterized using high strain rate data and its simulation predictions compared to a gas gun impact experiment wherein a Polycarbonate plate is subjected to the impact of a steel sphere at temperatures between 23–80 °C and 56–75 m/s.
Lars Watschke, Thorsten Passow, Frank Fuchs, Lutz Kirste, Rachid Driad, Frank Rutz, Stefano Leone, Robert Rehm, Oliver Ambacher
AlGaN avalanche Schottky diodes with high Al-content
2019 Jpn J Appl Phys, Band: 58, Seite: SCCC11

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R.Amirpour, D.Schwantuschke, P.Brueckner, R.Quay, O.Ambacher
AlGaN/GaN High Electron-mobility Varactors on Silicon Substrate
2019 12th German Microwave Conference (GeMiC), Seiten: 244 - 247

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S. Moench, R. Reiner, P. Waltereit, D. Meder, M. Basler, R. Quay, O. Ambacher, I. Kallfass
Asymmetrical Substrate-Biasing Effects at up to 350V Operation of Symmetrical Monolithic Normally-Off GaN-on-Si Half-Bridges
2019 IEEE, Seiten: 28 - 35

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Reichel Christian, Fell Andreas, Hermle Martin, Glunz Stefan
Back-Contacted Back-Junction Si Solar Cells with Locally Overcompensated Diffusion Regions - Comparison of Buried Emitter and Floating Base Design
2019 physica status solidi (a), Band: 216, Nummer: 4, Seite: 1800791
KurzfassungBack-contacted back-junction n-type Si solar cells with locally overcompensated diffusion regions are investigated in two different designs. In the “buried emitter” design, boron-doped (B-doped) emitter diffusions are partially diffused and locally overcompensated by phosphor-doped (P-doped) back surface field (BSF) diffusions, leading to n-type regions that are overlapping the p-type regions. In the “floating base” design, the B-diffusions are diffused on the entire rear side, so that the P-diffusions are separated from the base by the emitter. Hence, p-type regions exist between the n-type regions, creating opposing p-n junctions and a base that is floating. For the latter design with an efficiency of 17.1%, the open-circuit voltage Voc, the short-circuit current density Jsc, and the fill factor FF are significantly reduced by about 25mV, 5mAcm2, and 4%, respectively, compared to the buried emitter design where 678mV, 41.5mAcm2, and 76.1%, respectively, and an efficiency of 21.4% can be achieved. Two-dimensional numerical device simulations reveal that, besides junction and/or shunt leakage currents, recombination at the surface of the emitter and electron transport in the Band P-diffusions due to the opposing p-n junctions are detrimental for the performance of the “floating base” solar cell.
Fiacre E. Rougieux, Wolfram Kwapil, Friedemann Heinz, Manjula Siriwardhana, Martin c. Schubert
Contactless transient carrier spectroscopy and imaging technique using lock-in free carrier emission and absorption
2019 Scientific Reports, Band: 9, Nummer: 1, Seite: 14268
Kurzfassungin this paper we present a contactless transient carrier spectroscopy and imaging technique for traps in silicon. At each pixel, we fit the transient decay of the trap emission which allows us to obtain both the trap time constant and trap concentration. Here we show that this technique allows for high-resolution images. furthermore, this technique also allows to discriminate between the presence of thermal donors or oxygen precipitates in as-grown wafers, without requiring a thermal donor killing step.
M. Ćwikliński, P.Brueckner, S.Leone, C.Friesicke, H.Maßler, R.Lozar, S.Wagner, R.Quay, O.Ambacher
D-Band and G-Band High-Performance GaN Power Amplifier MMICs
2019 IEEE T Microw Theory, Band: 67, Nummer: 12, Seiten: 5080 - 5089
S.Roscher, R.Hoffmann, O.Ambacher
Determination of the graphene-graphite ratio of graphene powder by Raman 2D band symmetry analysis
2019 J Anal Methods Chem, Seiten: 1224 - 1228
R.Reiner, V.Zuebig, L.Pinti, P.Reinke, D.Meder, S.Moench, F.Benkhelifa, R.Quay, V.Cimalla, C.Nebel, O.Ambacher
Diamond Schottky-Diode in a Non-Isolated Buck Converter
2019 PCIM Europe 2019; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Seiten: 1 - 5

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Messmer Christoph, Fell Andreas, Feldmann Frank, Wohrle Nico, Schon Jonas, Hermle Martin
Efficiency Roadmap for Evolutionary Upgrades of PERC Solar Cells by TOPCon: Impact of Parasitic Absorption
2019 IEEE Journal of Photovoltaics
Kurzfassungsiehe PDF
S.Leone, F.Benkhelifa, L.Kirste, C.Manz, R.Quay, O.Ambacher
Epitaxial growth optimization of AlGaN/GaN high electron mobility transistor structures on 3C-SiC/Si
2019 J Appl Phys, Band: 125, Nummer: 23, Ergänzungsband: 235701
A.Ding, N.Kurz, R.Driad, Y.Lu, R.Lozar, T.Christoph, L.Kirste, O.Ambacher, A.Žukauskaitė
Experimental determination of Al1-xScxN thin film thermo-electro-acoustic properties up to 140°C by using SAW resonators
2019 IEEE International Ultrasonics Symposium (IUS), Kobe, Japan, Seiten: 710 - 715

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N.Kurz, A.Ding, D.Urban, Y.Lu, L.Kirste, N.Feil, A.Žukauskaitė, O.Ambacher
Experimental determination of the electro-acoustic properties of thin film AlScN using surface acoustic wave resonators
2019 J Appl Phys, Band: 126, Nummer: 7, Ergänzungsband: 075106
KurzfassungN. Kurz, A. Ding, D. F Urban, Y. Lu, L. Kirste, N. M Feil, A. Žukauskaitė, O. Ambacher, Experimental determination of the electro-acoustic properties of thin film AlScN using surface acoustic wave resonators (2019) Journal of Applied Physics 126 (7), 075106. doi: 10.1063/1.5094611
S. Backe, F. Balle, B. Hannemann, S. Schmeer, U.P. Breuer
Fatigue properties of multifunctional metal‐ and carbon‐fibre‐reinforced polymers and intrinsic capabilities for damage monitoring
2019 Fatigue Fract Eng M, Nummer: 42, Seiten: 143 - 151
M.Baeumler, Y.Lu, N.Kurz, L.Kirste, M.Prescher, T.Christoph, J.Wagner, A.Žukauskaitė, O.Ambacher
Finite Element Analysis of SAW Propagation Characteristics in c-plane (0001) and a-plane (11-20) AlScN Thin Films
2019 IEEE International Ultrasonics Symposium (IUS), Kobe, Japan, Seiten: 2588 - 2591

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Abdel-Khalek H, Schäfer M, Vásquez Torres RA, Unnewehr J, Weidlich A
Forecasting Cross-Border Power Transmission Capacities in Central Western Europe Using Artificial Neural Networks
2019 Energy Informatics, Band: 2, Ergänzungsband: 1, Seiten: 1 - 13

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Vadim Lebedev, Taro Yoshikawa, Christian Giese, Lutz Kirste, Agnė Žukauskaitė, Andreas Graff, Frank Meyer, Frank Burmeister, Oliver Ambacher
Formation of icosahedron twins during initial stages of heteroepitaxial diamond nucleation and growth
2019 J Appl Phys, Band: 125, Nummer: 7, Seite: 075305

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S.Roscher, R.Hoffmann, M.Prescher, P.Knittel, O.Ambacher
High voltage electrochemical exfoliation of graphite for high-yield graphene production
2019 Rsc Adv, Band: 9, Nummer: 50, Seiten: 29305 - 29311
Felix Heinz, Dirk Schwantuschke, Arnulf Leuther, Oliver Ambacher
Highly Scalable Distributed High Electron Mobility Transistor Model
2019 IEEE, Seiten: 1286 - 1288

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Ludmila Cojocaru, Karl Wienands, Ulas Erdil, Patricia SC Schulze, Laura E Mundt, Alexander J Bett, Matthias Breitwieser, Florian Lombeck, Mario Prescher, Lutz Kirste, Severin Vierrath, Jan Christoph Goldschmidt, Stefan W Glunz
Hybrid Evaporation/Spray-Coating Process for a Simplified and Controllable Production of Perovskite Solar Cells
2019 IEEE J Photovolt, Band: 10, Nummer: 1, Seiten: 276 - 286
KurzfassungRecently, hybrid processing using evaporation and spin-coating has been applied for the fabrication of perovskite silicon tandem solar cells with record power conversion efficiencies (PCEs) of 25.2%. To achieve large area, high-throughput production of solar cells, spray-coating, a well-known scalable method used in the industry, has advantages over spin-coating. Therefore, we apply a hybrid method using the evaporation of PbI 2 and spraying of methylammonium iodide (MAI) for the fabrication of perovskite solar cells. This article presents a systematic study of sprayed MAI amount and processing parameters on the performance of solar cells. We find clear correlations between the processing parameters of the sprayed MAI, the crystallinity of CH 3 NH 3 PbI 3 and the PCE of the resulting PSCs. High crystallinity and morphology of the CH 3 NH 3 PbI 3 film is achieved using a slow nozzle speed of 30 mm·s −1 …
Post Regina, Niewelt Tim, Schön Jonas, Schindler Florian, Schubert Martin
Imaging Interstitial Iron Concentrations in Gallium-Doped Silicon Wafers
2019 physica status solidi (a), Band: 121, Seite: 1800655
KurzfassungIn this work, the established method of iron imaging is transferred from B-doped silicon to Ga-doped material. For this purpose, the pairing and splitting conditions are investigated and a preparation procedure suggested that ensures a sufficient fraction of iron–gallium pairing and splitting, respectively. Furthermore the defect parameters available in literature are compared and evaluated for a suitable description of the injection dependent carrier lifetime measurements. A parameter set that enables a coherent and adequate iron evaluation is suggested. Thus, a robust method for spatially resolved determination of the interstitial iron concentration in Ga-doped silicon wafers is presented.
Messmer Christoph, Bivour Martin, Luderer Christoph, Tutsch Leonard, Schon Jonas, Hermle Martin
Influence of Interfacial Oxides at TCO/Doped Si Thin Film Contacts on the Charge Carrier Transport of Passivating Contacts
2019 IEEE Journal of Photovoltaics, Seite: to be published
Kurzfassungsiehe PDF
T.Yoshikawa, D.Herrling, F.Meyer, F.Burmeister, C.Nebel, O.Ambacher, V.Lebedev
Influence of substrate holder configurations on bias enhanced nucleation area for diamond heteroepitaxy: Toward wafer-scale single-crystalline diamond synthesis
2019 J Vac Sci Technol A
Schube Jörg, Fellmeth Tobias, Jahn Mike, Keding Roman, Glunz Stefan
Inkjet‐ and FlexTrail‐Printing with Low Silver Consumption for Silicon Heterojunction Solar Cells
2019 physica status solidi (RRL) - Rapid Research Letters, Band: 3, Seite: 1900186
KurzfassungBifacial busbarless silicon heterojunction (SHJ) solar cells with an edge length of 156.8mm are metalized using a commercially available Ag nanoparticle ink on the front side. By means of inkjet-printing, a maximum conversion efficiency of 23.3% is achieved. The influence of the inkjet-printed layer number per contact finger, which is varied from one to five, on cell performance is investigated in detail. Optima are found for one and two layers, which ensure both high efficiency and low silver consumption. Furthermore, a novel metallization technology, called FlexTrail-printing, is introduced. Using the same ink as in the case of inkjet-printing, the finger width is reduced from 75 1 to 16 1 μm. This results in an enhanced short-circuit current density and, therefore, a maximum conversion efficiency of 23.7%. Only 0.3 0.1 mg Ag nanoparticle ink (deposited at 25 C substrate temperature) is consumed during FlexTrail-printing on a large-area wafer (area of 244.3 cm2) with a front grid of 80 fingers.
Stefan Moench, R.Reiner, P.Waltereit, R.Quay, O.Ambacher, I.Kallfass
Integrated Current Sensing in GaN Power ICs
2019 31st International Symposium on Power Semiconductor Devices and ICs (ISPSD), Seiten: 111 - 114

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K.Frei, B.Trejo-Hernàndez, S.Schuett, L.Kirste, M.Prescher, R.Aidam, S.Mueller, P.Waltereit, O.Ambacher, M.Fiederle
Investigation of growth parameters for ScAlN-barrier HEMT structures by plasma-assisted MBE
2019 Jpn J Appl Phys, Band: 58, Seite: SC1045
R.Amipour, D.Schwantuschke, F.van Raay, P.Brueckner, R.Quay, O.Ambacher
Large-Signal Modeling of a Scalable High-Q AlGaN/GaN High Electron-Mobility Varactor
2019 IEEE T Microw Theory, Seiten: 922 - 927
Schubert Martin, Schindler Florian, Schön Jonas, Kwapil Wolfram, Benick Jan, MüCller Ralph, Heinz Friedemann, Fell Andreas, Riepe Stephan, Morishige Ashley
Limiting defects in n‐type multicrystalline silicon solar cells
2019 physica status solidi (a)
KurzfassungMulticrystalline solar cells made from n‐type silicon feedstock have shown record efficiencies of 22.3% in a TOPCon cell structure. Still, material related carrier recombination limits the attainable efficiency. In this article, we summarize findings of metallic impurity and structural defect concentration present in n‐type mc silicon and elaborate on their limiting properties on carrier lifetime and cell performance. Applying a dedicated model for carrier recombination at precipitate‐silicon interfaces it is demonstrated that carrier recombination at metallic precipitates may dominate in the analyzed material. Direct evidence of the recombination activity of iron precipitates in n‐type silicon is given by an analysis of intentionally grown iron precipitates: From a comparison of μXRF analyses of differently sized iron precipitates and local carrier recombination from μPL a direct correlation to enhanced carrier recombination is found. From these results, it is concluded that high‐performance n‐type mc silicon is limited by recombination at (decorated) structural defects namely dislocation clusters and grain boundaries whereas defects in the inner grains are not limiting the efficiency potential. Finally, cell degradation under illumination and elevated temperature for n‐type multicrystalline silicon solar cells are discussed.
Lucija Rakocevic, Laura E Mundt, Robert Gehlhaar, Tamara Merckx, Tom Aernouts, Martin C Schubert, Stefan W Glunz, Jef Poortmans
Loss Analysis in Perovskite Photovoltaic Modules
2019 Solar RRL, Band: 3, Nummer: 12
R.Aidam, O.Ambacher, E.Diwo, B.Godejohann, L.Kirste, T.Lim, R.Quay, P.Waltereit
MBE of III-Nitride Semiconductors for Electronic Devices
2019 Molecular Beam Epitaxy: Materials and Device Applications
S.Leone, J.Ligl, C.Manz, L.Kirste, T.Fuchs, H.Menner, M.Prescher, J.Wiegert, A.Žukauskaitė, R.Quay, O.Ambacher
Metal‐Organic Chemical Vapor Deposition of Aluminum Scandium Nitride
2019 Phys Status Solidi-r
Schäfer, Frank, Kenkmann, Thomas, Hiermaier, Stefan
Obituary for a brilliant materials scientist - on Klaus Thoma's death
2019 Meteorit Planet Sci, Nummer: 1, Seiten: 254 - 255
Weidlich A, Zaidi A
Operational Flexibility of Small-Scale Electricity-Coupled Heat Generating Units
2019 Technology and Economics of Smart Grids and Sustainable Energy, Band: 4, Nummer: 8, Seiten: 1 - 16
KurzfassungHeat generation that is coupled with electricity usage, like combined heat and power generators or heat pumps, can provide operational flexibility to the electricity sector. In order to make use of this in an optimized way, the flexibility that can be provided by such plants needs to be properly quantified. This paper proposes a method for quantifying the flexibility provided through a cluster of such heat generators. It takes into account minimum operational time and minimum down-time of heat generating units. Flexibility is defined here as the time period over which plant operation can be either delayed or forced into operation, thus providing upward or downward regulation to the power system on demand. Results for one case study show that a cluster of several smaller heat generation units does not provide much more delayed operation flexibility than one large unit with the same power, while it more than doubles the forced operation flexibility. Considering minimum operational time and minimum down-time of the units considerably limits the available forced and delayed operation flexibility, especially in the case of one large unit.

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Martina Baeumler, Yuan Lu, Nicolas Kurz, Lutz Kirste, Mario Prescher, Tim Christoph, Joachim Wagner, Agnė Žukauskaitė, Oliver Ambacher
Optical constants and band gap of wurtzite Al1−xScxN/Al2O3 prepared by magnetron sputter epitaxy for scandium concentrations up to x = 0.41
2019 J Appl Phys, Band: 126, Nummer: 4, Seite: 045715

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Watson, Erkai, Gulde, Max, Kortmann, Lukas, Higashide, Masumi, Schäfer, Frank, Hiermaier, Stefan
Optical fragment tracking in hypervelocity impact experiments
2019 Acta Astronaut, Seiten: 111 - 117
KurzfassungIn-orbit impacts between satellites and space debris lead to varying degrees of fragmentation, ranging anywhere from minor damage to complete breakups. In this paper, we describe an experimental measurement approach for studying fragmentation caused by hypervelocity impact in the laboratory. We investigate impacts on thin aluminum bumper plates with the goal of measuring individual fragment velocities and sizes generated by hypervelocity impact. The experimental setup, commonly used in fluid dynamics for Particle Tracking Velocimetry, consists of using a laser plane and high-speed video camera to track the motion of debris fragments. We describe the fragment tracking algorithm and demonstrate its ability to determine fragment velocity and sizes in specific hypervelocity impact experiments performed at Fraunhofer EMI. The measurement technique enables quantitative data, at an unprecedented level of detail, to be measured from hypervelocity impact fragmentation experiments in the lab, which can be applied to understanding the effects of satellite collisions and improving breakup models.
Mundt Laura, Kwapil Wolfram, Yakoob Mohammed, Herterich Jan, Kohlstadt Markus, Wurfel Uli, Schubert Martin, Glunz Stefan
Quantitative Local Loss Analysis of Blade-Coated Perovskite Solar Cells
2019 ´, Seite: 1–8
KurzfassungMicroRNAs (miRNAs) are post-transcriptional regulators that repress the expression of their targets. They are known to work cooperatively with genes and play important roles in numerous cellular processes. Identification of miRNA regulatory modules (MRMs) would aid deciphering the combinatorial effects derived from the many-to-many regulatory relationships in complex cellular systems. Here, we develop an effective method called BiCliques Merging (BCM) to predict MRMs based on bicliques merging. By integrating the miRNA/mRNA expression profiles from The Cancer Genome Atlas (TCGA) with the computational target predictions, we construct a weighted miRNA regulatory network for module discovery. The maximal bicliques detected in the network are statistically evaluated and filtered accordingly. We then employed a greedy-based strategy to iteratively merge the remaining bicliques according to their overlaps together with edge weights and the gene-gene interactions. Comparing with existing methods on two cancer datasets from TCGA, we showed that the modules identified by our method are more densely connected and functionally enriched. Moreover, our predicted modules are more enriched for miRNA families and the miRNA-mRNA pairs within the modules are more negatively correlated. Finally, several potential prognostic modules are revealed by Kaplan-Meier survival analysis and breast cancer subtype analysis.
F.Heinz, D.Schwantuschke, M.Ohlrogge, A.Leuther, O.Ambacher
RF-Noise Model Extraction Procedure for Distributed Multiport Models
2019 12th German Microwave Conference (GeMiC), Seiten: 260 - 263

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Brown T, Schäfer M, Greiner M
Sectoral Interactions as Carbon Dioxide Emissions Approach Zero in a Highly-Renewable European Energy System
2019 Energies, Band: 12, Seite: 1032
KurzfassungMeasures to reduce carbon dioxide emissions are often considered separately, in terms of electricity, heating, transport, and industry. This can lead to the measures being prioritised in the wrong sectors, and neglects interactions between the sectors. In addition, studies often focus on specific greenhouse gas reduction targets, despite the uncertainty regarding what targets are desirable and when. In this paper, these issues are examined for the period after 2030 in an existing openly-available, hourly-resolved, per-country, and highly-renewable model of the European energy system, PyPSA-Eur-Sec-30, that includes electricity, land transport, and space and water heating. A parameter sweep of different reduction targets for direct carbon dioxide emissions is performed, ranging from no target down to zero direct emissions. The composition of system investments, the interactions between the energy sectors, shadow prices, and the market values of the system components are analysed as the carbon dioxide limit changes. Electricity and land transport are defossilised first, while the reduction of emissions in space and water heating is delayed by the expense of new components and the difficulty of supplying heat during cold spells with low wind and solar power generation. For deep carbon dioxide reduction, power-to-gas changes the system dynamics by reducing curtailment and increasing the market values of wind and solar power. Using this model setup, cost projections for 2030, and optimal cross-border transmission, the costs of a zero-direct-emission system in these sectors are marginally cheaper than today’s system, even before the health and environmental benefits are taken into account.

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Bett Alexander J., Winkler Kristina M., Bivour Martin, Cojocaru Ludmila, Kabakli Özde Ş., Schulze Patricia S.C., Siefer Gerald, Tutsch Leonard, Hermle Martin, Glunz Stefan W., Goldschmidt Jan Christoph
Semi-Transparent Perovskite Solar Cells with ITO Directly Sputtered on Spiro-OMeTAD for Tandem Applications
2019 Acs Appl Mater Inter, Band: 11, Nummer: 49, Seiten: 45796 - 4580
KurzfassungPerovskite silicon tandem solar cells have the potential to overcome the efficiency limit of single-junction solar cells. For both monolithic and mechanically stacked tandem devices, a semi-transparent perovskite top solar cell, including a transparent contact, is required. Usually, this contact consists of a metal oxide buffer layer and a sputtered transparent conductive oxide. In this work, semi-transparent perovskite solar cells in the regular n–i–p structure are presented with tin-doped indium oxide (ITO) directly sputtered on the hole conducting material Spiro-OMeTAD. ITO process parameters such as sputter power, temperature, and pressure in the chamber are systematically varied. While a low temperature of 50 °C is crucial for good device performance, a low sputter power has only a slight effect, and an increased chamber pressure has no influence on device performance. For the 5 × 5 mm2 perovskite cell with a …
Feldmann Frank, Schön Jonas, Niess Jürgen, Lerch Wilfried, Hermle Martin
Studying dopant diffusion from Poly-Si passivating contacts
2019 Solar Energy Materials and Solar Cells, Band: 200, Seite: 109978
KurzfassungThe diffusion of dopants from the poly-Si layer through the interfacial oxide into the crystalline silicon wafer is studied experimentally and via numerical simulation. It is found that phosphorus piles up at the poly-Si/SiOx interface but boron readily diffuses through the oxide into the silicon and thereby forms a less shallow junction which adversely affects surface passivation. Although boron diffusion was suppressed by using a nitrided oxide – realized by a plasma oxidation process – a reduction in passivation was observed due to deterioration of the interface. Via 1D and 3D process simulation it was established that diffusion through pinholes contributed little to the aggregate diffusion profiles measured by ToF-SIMS but direct diffusion through the oxide was the main diffusion mechanism. The segregation coefficient at the poly-Si/SiOx interface and the diffusivity in SiOx were determined. Using these parameters simulation-based predictions were conducted in order to pave the way for future optimization of hole-selective passivating contacts.
Kwapil Wolfram, Wasmer Sven, Fell Andreas, Greulich Johannes, Schubert Martin
Suns-ILIT: Contact-less determination of local solar cell current-voltage characteristics.
2019 Solar Energy Materials and Solar Cells, Band: 191, Seite: 71–77
KurzfassungWe present a novel method to analyze the local current-voltage I-V characteristics of both solar cells and cell precursors. The method, which we call “Suns-ILIT”, is based on illuminated lock-in thermography (ILIT) measurements and photoluminescence imaging (PLI) in open-circuit conditions with varying illumination intensities. Compared to conventional techniques for the determination of local solar cell parameters, the advantage of Suns-ILIT lies in the high accuracy while imposing minimal requirements on the sample. In particular, no electrical contact to the sample is needed. We derive the necessary equations from the contributions to the power dissipation and investigate the impact of the Peltier heating and cooling on the final outcome. The method is applied to a standard multicrystalline silicon PERC solar cell for demonstration.
Würfel Uli, Perdigón Toro Lorena, Kurpiers Jona, Wolff Christian, Caprioglio Pietro, Rech Jeromy, Zhur Jingshuai, Zhan Xiaowei, You Wei, Shoaee Safa, Neher Dieter, Stolterfoht Martin
The Recombination between Photogenerated and Electrode-Induced Charges Dominates the Fill Factor Losses in Optimized Organic Solar Cells
2019 The Journal of Physical Chemistry Letters
KurzfassungCharge extraction in organic solar cells (OSCs) is commonly believed to be limited by bimolecular recombination of photogenerated charges. Yet, the fill factor of OSCs is usually almost entirely governed by recombination processes that scale with the first-order of the light intensity. This linear loss was often interpreted to be a consequence of geminate or trap-assisted recombination. Numerical simulations show that this linear dependence is a direct consequence of the large amount of excess dark charge near the contact. The first-order losses increase with decreasing mobility of minority carriers and we discuss the impact of several material and device parameters on this loss mechanism. This work highlights that OSCs are especially vulnerable to injected charges as a result of their poor charge transport properties. This implicates that dark charges need to be better accounted for when interpreting electro-optical measurements and charge collection based on simple figures of merit. Charge extraction in organic solar cells (OSCs) is commonly believed to be limited by bimolecular recombination of photogenerated charges. Yet, the fill factor of OSCs is usually almost entirely governed by recombination processes that scale with the first-order of the light intensity. This linear loss was often interpreted to be a consequence of geminate or trap-assisted recombination. Numerical simulations show that this linear dependence is a direct consequence of the large amount of excess dark charge near the contact. The first-order losses increase with decreasing mobility of minority carriers and we discuss the impact of several material and device parameters on this loss mechanism. This work highlights that OSCs are especially vulnerable to injected charges as a result of their poor charge transport properties. This implicates that dark charges need to be better accounted for when interpreting electro-optical measurements and charge collection based on simple figures of merit.// Charge extraction in organic solar cells (OSCs) is commonly believed to be limited by bimolecular recombination of photogenerated charges. Yet, the fill factor of OSCs is usually almost entirely governed by recombination processes that scale with the first-order of the light intensity. This linear loss was often interpreted to be a consequence of geminate or trap-assisted recombination. Numerical simulations show that this linear dependence is a direct consequence of the large amount of excess dark charge near the contact. The first-order losses increase with decreasing mobility of minority carriers and we discuss the impact of several material and device parameters on this loss mechanism. This work highlights that OSCs are especially vulnerable to injected charges as a result of their poor charge transport properties. This implicates that dark charges need to be better accounted for when interpreting electro-optical measurements and charge collection based on simple figures of merit.
Rafizadeh Saeid, Wienands Karl, Mundt Laura, Bett Alexander, Schulze Patricia, Andreani Lucio, Hermle Martin, Glunz Stefan, Goldschmidt Jan
The Role of Surface Passivation Layer Preparation on Crystallization and Optoelectronic Performance of Hybrid Evaporated-Spincoated Perovskite Solar Cells
2019 IEEE Journal of Photovoltaics, Seite: 1–8
KurzfassungThe main advantages of the organic–inorganic halide perovskite solar cell technology are high efficiencies achieved after short development time in combination with rather simple solutionbased processing. In this paper, we address remaining challenges by presenting a low-temperature two-step hybrid evaporationspincoating method that combines high reproducibility with easy fabrication and high stabilized efficiencies, which is compatible with the processing of pervoskite silicon tandem solar cells and avoids using hazardous solvents such as dimethylformamide and dimethylsulfoxide. Lead iodide (PbI2) is thermally evaporated and subsequently converted into a compact crystalline perovskite layer by methylammonium iodide spincoating. Moreover, the role of the interface passivation between perovskite absorber and electron transport layer on crystallization and optoelectronic properties of the perovskite absorber is investigated within a systematic thickness and concentration variation of [6, 6]-phenyl-C61-butyric acid methyl ester passivation layer and by analyzing charge extraction with spatial and time resolved photoluminescence measurements. With an optimized charge extraction, 18.2% stabilized efficiency under one sun illumination is achieved. This is the highest value reported so far for the single junction perovskite solar cells made by a two-step hybrid evaporation-spincoating method.
Sandoval Murillo, José Luis, Osen, Raffael, Hiermaier, Stefan, Ganzenmüller, Georg
Towards understanding the mechanism of fibrous texture formation during high-moisture extrusion of meat substitutes
2019 J Food Eng, Seiten: 8 - 20
KurzfassungThis paper investigates the physical mechanisms of structure formation during high-moisture extrusion of vegetable proteins. Our model starts from the observation that extrudates with fibrous, meat-like structures exhibit water-rich and protein-rich domains. The origin and structure of these domains is attributed to a spinodal phase-separation process which occurs upon cooling of the extrudate. We investigate the process using continuum-mechanics simulations, considering the combined effects of viscous flow, thermal diffusivity, and the mixing thermodynamics of water and protein. This multi-physics problem is numerically solved using an unconventional mesh-free approach, the material point method (MPM), combined with the Cahn- Hilliard model of phase separation. The method incorporates both Eulerian and Lagrangian aspects, and is well suited to model multicomponent flows of history-dependent materials. Our simulations show that fiber-like structures are obtained when the ratio of phase separation rate, heat conduction rate, and flow rate are matched within a narrow window. Our results predict that the shape of the temperature profile within the cooling channel determines the structure of the phase-separated state. These findings suggest that the physical mechanism which causes fibrous structure formation is given by spinodal phase separation under the influence of a temperature gradient.
Bett Alexander J., Schulze Patricia S.C., Winkler Kristina M., Kabakli Özde S., Ketterer Ines, Mundt Laura E., S. Kasimir Reichmuth, Gerald Siefer, Ludmila Cojocaru, Leonard Tutsch, Martin Bivour, Martin Hermle, Stefan W. Glunz, Jan Christoph Goldschmidt
Two‐terminal Perovskite silicon tandem solar cells with a high‐Bandgap Perovskite absorber enabling voltages over 1.8 V
2019 Progress in Photovoltaics: Research and Applications, Band: 2, Nummer: 5, Seite: 17032
KurzfassungPerovskite silicon tandem solar cells are a promising technology to overcome the efficiency limit of silicon solar cells. Although highest tandem efficiencies have been reported for the inverted p‐i‐n structure, high‐efficiency single junction perovskite solar cells are mostly fabricated in the regular n‐i‐p architecture. In this work, regular n‐i‐p perovskite solar cells with a high‐bandgap mixed cation mixed halide absorber suitable for tandem solar cells are investigated by compositional engineering and the open‐circuit voltage is improved to over 1.12 V using a passivating electron contact. The optimized perovskite solar cell is used as a top cell in a monolithic perovskite silicon tandem device with a silicon heterojunction bottom cell allowing for voltages up to 0.725 V. The tandem solar cells with an active area of 0.25 cm2 achieve record open‐circuit voltages of up to 1.85 V and have efficiencies over 20%. Analyzing the perovskite absorber by spatially resolved photoluminescence measurements shows a homogenous and stable emission at ~ 1.7 eV which is an optimal value for tandem applications with silicon. The tandem solar cells are mainly limited due to a low current. A spectrometric characterization reveals that the perovskite solar cell is current limiting which could be improved by a thicker perovskite absorber.
F. Staab, F. Balle
Ultrasonic torsion welding of ageing-resistant Al/CFRP joints: Properties, microstructure and joint formation
2019 Ultrasonics, Nummer: 93, Seiten: 139 - 144
Häring, Ivo, Ramin, Malte von, Stottmeister, Alexander, Schäfer, Johannes, Vogelbacher, Georg, Brombacher, Bernd, Pfeiffer, Mercy, Restayn, Elena-Maria, Ross, Katharina, Schneider, Johannes, Hiermaier, Stefan
Validated 3D spatial stepwise quantitative hazard, risk and resilience analysis and management of explosive events in urban areas
2019 European journal for security research 4, Nummer: 1, Seiten: 93 - 129
KurzfassungUrban physical security and resilience with respect to accidental and intentional explosive events are an increasing issue regarding civil safety and security of modern societies and their citizens. Examples include industrial on-site explosions, gas explosions or terrorist attacks. In particular, multiple, simultaneous and maliciously time-coordinated events are an increasing event type such as complex attack events consisting of targeted combinations of improvised explosive devices. The paper presents a comprehensive, tailorable and stepwise process. This includes methodologies for scenario, hazard, damage, exposure, event frequency, risk and resilience analysis that have been developed, refined and praxis-tested over decades. The focus is on a summarizing description of the modern best practice approach, the validation efforts undertaken for each step as well as two detailed case studies for exemplary presentation and overall validation. In a comprehensive table, the present approach is compared with other state-of-the-art approaches. The paper shows a refined process how to systematically improve resilience when using the tool, in particular through barriers at explosive sites and at exposed sites of various geometries. Furthermore, along the presentation a set of quality requirements regarding explosive event risk and resilience analyses are provided as collected over the years from the in-field, user group and engineering science perspective as well as a broad outlook on extension options for the future.
F.Thome, A.Leuther, F.Heinz, O.Ambacher
W-Band LNA MMICs Based on a Noise-Optimized 50-nm Gate-Length Metamorphic HEMT Technology
2019 IEEE MTT-S International Microwave Symposium (IMS), Seiten: 168 - 171

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2018

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F.Thome, A.Leuther, J.D.Gallego, F.Schafer, M.Schlechtweg, O.Ambacher
70-116-GHz LNAs in 35-nm and 50-nm Gate-Length Metamorphic HEMT Technologies for Cryogenic and Room-Temperature Operation
2018 IEEE MTT-S International Microwave Symposium Digest, Nummer: 6, Ergänzungsband: 8439685, Seiten: 1495 - 1498

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A.Dyck, M.Roesch, A.Tessmann, A.Leuther, M.Kuri, H.Maßler, S.Wagner, D.Meder, B.Weismann-Thaden, M.Schlechtweg, O.Ambacher
A 300 GHz microstrip multilayered antenna on quartz substrate
2018 International Workshop on Antenna Technology (iWAT), Seiten: 1 - 3

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B.Amado-Rey, Y.Campo-Roca, C.Friesicke, F.vanRaay, H.Massler, A.Leuther, O.Ambacher
A G-Band Broadband Balanced Power Amplifier Module Based on Cascode mHEMTs
2018 IEEE Microwave and Wireless Components Letters, Band: 28, Nummer: 10, Seiten: 924 - 926
M.Ćwikliński, C.Friesicke, F.van Raay, H.Massler, R.Quay, O.Ambacher
A Novel Type of Broadband Radial Stub
2018 2018 48th European Microwave Conference (EuMC), Madrid, Seiten: 1093 - 1096

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S. Backe, F. Balle
A novel short-time concept for fatigue life estimation of carbon (CFRP) and metal/carbon fiber reinforced polymer (MCFRP)
2018 Int J Fatigue, Band: 116, Seiten: 317 - 322

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K. Losch, S. Schuff, F. Balle, T. Beck, C. Redenbach
A stochastic microstructure model for particle reinforced aluminium matrix composites
2018 J Microsc-oxford
B.Amado-Rey, Y.Campos-Roca, F.van Raay, C.Friesicke, S.Wagner, H.Massler, A.Leuther, O.Ambacher
Analysis and Development of Submillimeter-Wave Stacked-FET Power Amplifier MMICs in 35-nm mHEMT Technology
2018 IEEE T Thz Sci Techn, Band: 8, Nummer: 3, Seiten: 357 - 364
B.Amado-Rey, Y.Campos-Roca, C.Friesicke, F.van Raay, H.Massler, A.Leuther, O.Ambacher
Analysis of 4-way divider MMICs in GaAs technology for H-band applications
2018 11th German Microwave Conference (GeMiC), Seiten: 327 - 330

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L.Hahn, F.Fuchs, L.Kirste, R.Driad, F.Rutz, T.Passow, K.Koehler, R.Rehm, O.Ambacher
Avalanche multiplication in AlGaN-based heterostructures for the ultraviolet spectral range
2018 Appl Phys Lett, Band: 112, Nummer: 15, Ergänzungsband: 151102
Feldmann Frank, Nogay Gizem, Löper Philipp, Young David, Lee Benjamin, Stradins Paul, Hermle Martin, Glunz Stefan
Charge carrier transport mechanisms of passivating contacts studied by temperature-dependent J-V measurements
2018 Solar Energy Materials and Solar Cells, Band: 178, Seite: 15–19
KurzfassungThe charge carrier transport mechanism of passivating contacts which feature an ultra-thin oxide layer is investigated by studying temperature-dependent current-voltage characteristics. 4-Terminal dark J-V measurements at low temperatures reveal non-linear J-V characteristics of passivating contacts with a homogeneously grown silicon oxide, which result in an exponential increase in contact resistance towards lower temperature. The attempt to describe the R(T) characteristic solely by thermionic emission of charge carriers across an energy barrier leads to a significant underestimation of the resistance by several orders of magnitude. However, the data can be described properly with the metal-insulator-semiconductor (MIS) theory if tunneling of charge carriers through the silicon oxide layer is taken into account. Furthermore, temperature-dependent light J-V characteristics of solar cells featuring passivating contacts at the rear revealed a FF drop at T<205 K, which is near the onset temperature of the exponential increase in contact resistivity.
Voglstätter C, Weidlich A, Fischer D, Schmidinger J
Control algorithms for electrolyzers - Hydrogen from green electricity
2018 BKW, Band: 70, Nummer: 7/8, Seiten: 36 - 39
KurzfassungIn 2017, the share of renewables in power generation in Germany was around 33 %. By 2030, according to the will of the federal government, it should be as high as 65 %. A large proportion of electricity from wind and solar energy will in future require electricity storage. Particularly promising is the conversion to hydrogen. Research, industry and the energy sector are currently driving forward the development and use of water electrolysers. The Fraunhofer Institute for Solar Energy Systems ISE and the University of Applied Sciences Offenburg, in cooperation with the energy provider badenova and the gas network operator bnNetz have developed operating management algorithms for electrolyzers and tested them at research facilities. Within the project, the integration of hydrogen into municipal gas and electricity grids and into a local energy grid could be tested taking into account the current regulations and economic constraints. Thereby, the partners have laid important foundations for the use of the energy carrier hydrogen.
Schlachtberger D, Brown T, Schäfer M, Schramm S, Greiner M
Cost optimal scenarios of a future highly renewable European electricity system: Exploring the influence of weather data, cost parameters and policy constraints
2018 Energy, Band: 163, Seiten: 100 - 114
KurzfassungCost optimal scenarios derived from models of a highly renewable electricity system depend on the specific input data, cost assumptions and system constraints. Here this influence is studied using a techno-economic optimisation model for a networked system of 30 European countries, taking into account the capacity investment and operation of wind, solar, hydroelectricity, natural gas power gen- eration, transmission, and different storage options. A considerable robustness of total system costs to the input weather data and to moderate changes in the cost assumptions is observed. Flat directions in the optimisation landscape around cost-optimal configurations often allow system planners to choose between different technology options without a significant increase in total costs, for instance by replacing onshore with offshore wind power capacity in case of public acceptance issues. Exploring a range of carbon dioxide emission limits shows that for scenarios with moderate transmission expansion, a reduction of around 57% compared to 1990 levels is already cost optimal. For stricter carbon dioxide limits, power generated from gas turbines is at first replaced by generation from increasing renewable capacities. Non-hydro storage capacities are only built for low-emission scenarios, in order to provide the necessary flexibility to meet peaks in the residual load.

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Cojocaru Ludmila, Wienands Karl, Kim Tae, Uchida Satoshi, Bett Alexander, Rafizadeh Saeid, Goldschmidt Jan, Glunz Stefan
Detailed Investigation of Evaporated Perovskite Absorbers with High Crystal Quality on Different Substrates
2018 ACS applied materials & interfaces
KurzfassungDual-source vapor-phase deposition enables low-temperature fabrication of high-performance planar structure perovskite (CH3NH3PbI3) solar cells (PSCs), applicable in tandem devices or for industrial production with high homogeneity. Herein, we report low-temperature fabrication of high-efficiency PSCs by dual-source vapor-phase deposition and significance of TiO2 surface modification with [6,6]-phenyl C61 butyric acid methyl ester (PCBM) on cell performance. Co-evaporation of PbI2 and CH3NH3I, as confirmed by X-ray diffraction and high-resolution transmission electron microscopy analyses, results in CH3NH3PbI3 layers with a well-crystallized tetragonal phase formed on both TiO2 and TiO2/PCBM electron-transport layers (ETLs). The devices with PCBM interlayer between TiO2 and CH3NH3PbI3 showed remarkably higher performance than those with TiO2 only, which was attributed to enhance charge extraction and reduced recombination at the TiO2/PCBM/CH3NH3PbI3 interface. The devices composed of evaporated CH3NH3PbI3 on top of the TiO2/PCBM and [2,2',7,7'-tetrakis( N, N-di- p-methoxyphenyl-amine)-9,9'-spirobifluorene] (Spiro-OMeTAD) as hole-transport material demonstrated power conversion efficiencies of 17.1% (reverse scan) and 13.4% (forward scan) with stabilized efficiency of over 16%, which is, to the best of our knowledge, the highest efficiency reported for evaporated perovskite solar cells using low-temperature fabrication method involving compact TiO2 layer as ETL. Furthermore, we show that this process can be used to deposit a CH3NH3PbI3 layer on top of a textured silicon substrate, which is the first step for preparing perovskite-silicon tandem devices with enhanced antireflection and light-trapping properties.
N.Kurz, F.Parsapour, V.Pashchenko, L.Kirste, V.Lebedev, P.Muralt, O.Ambacher, N.Pascal
Determination of Elastic and Piezoelectric Properties of Al0.84Sc0.16N Thin Films
2018 IEEE International Ultrasonics Symposium (IUS), Kobe, Japan, Seiten: 1 - 5
R.Amirpour, S.Krause, R.Quay, O.Ambacher
Dynamic Load Modulated Low-Voltage GaN PA Using Novel Low-Loss GaN Varactors
2018 48th European Microwave Conference (EuMC), Madrid, Seiten: 5 - 8
Laessig, Torsten, May, Michael, Heisserer, Ulrich, Riedel, Werner, Bagusat, Frank, Werff, Harm van der, Hiermaier, Stefan
Effect of consolidation pressure on the impact behavior of UHMWPE composites
2018 Compos Part B-eng, Band: 147, Seiten: 47 - 55
KurzfassungFor the first time, the influence of the manufacturing process on the dynamic performance of ultra-high molecular weight polyethylene (UHMWPE, Dyneema® HB26) composites is investigated. The material is significantly influenced by the hot-pressing parameters temperature and pressure. The ballistic resistance and shock wave behavior was characterized for the UHMWPE composite consolidated with three different pressures. In the case of UHMWPE composites, higher consolidation pressures result in a better ballistic performance. The shock wave behavior converges to high-density polyethylene (HDPE). Based on these observations, an analytical approach is proposed describing the equation of state as a function of consolidation pressure.
Rafizadeh Saeid, Wienands Karl, Schulze Patricia, Bett Alexander, Andreani Lucio, Hermle Martin, Glunz Stefan, Goldschmidt Jan
Efficiency Enhancement and Hysteresis Mitigation by Manipulation of Grain Growth Conditions in Hybrid Evaporated-Spincoated Perovskite Solar Cells
2018 ACS applied materials & interfaces
KurzfassungPerovskite solar cells became a game changer in the field of photovoltaics by reaching power conversion efficiencies (PCE) beyond 23%. To achieve even higher efficiencies it is necessary to increase the understanding of crystallization, grain formation and layer ripening. In this study, by a systematic variation of the MAI concentrations we changed the stoichiometry and thereupon the crystal growth conditions in MAPbI3 perovskite solar cells, prepared by a two-step hybrid evaporation-spincoating deposition method. Utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force miscroscopy (AFM), photoluminescence (PL) and current-voltage (J-V) characterization, we found that a relatively lower concentration of MAI or in other words higher content of remnant and unconverted PbI2 correlates with smaller and stronger interconnected grains, as well as with an improved optoelectronic performance of the solar cells and mitigation of hysteresis. Possible explanations are grain and interface passivation by the excess PbI2 and a positive contribution of the grain boundaries to current extraction.
Y.Lu, M.Reusch, N.Kurz, A.Ding, T.Christoph, M.Prescher, L.Kirste, O.Ambacher, A.Žukauskaitė
Elastic modulus and coefficient of thermal expansion of piezoelectric Al1−xScxN (up to x = 0.41) thin films
2018 APL Publishing, Band: 6, Nummer: 7
Reichel Christian, Würfel Uli, Winkler Kristina, Schleiermacher Hans-Frieder, Kohlstädt Markus, Unmüssig Moritz, Messmer Christoph, Hermle Martin, Glunz Stefan
Electron-selective contacts via ultra-thin organic interface dipoles for silicon organic heterojunction solar cells
2018 Journal of Applied Physics, Band: 123, Nummer: 2, Seite: 024505
KurzfassungIn the last years, novel materials for the formation of electron-selective contacts on n-type crystalline silicon (c-Si) heterojunction solar cells were explored as an interfacial layer between the metal electrode and the c-Si wafer. Besides inorganic materials like transition metal oxides or alkali metal fluorides, also interfacial layers based on organic molecules with a permanent dipole moment are promising candidates to improve the contact properties. Here, the dipole effect plays an essential role in the modification of the interface and effective work function of the contact. The amino acids L-histidine, L-tryptophan, L-phenylalanine, glycine, and sarcosine, the nucleobase adenine, and the heterocycle 4-hydroxypyridine were investigated as dipole materials for an electronselective contact on the back of p- and n-type c-Si with a metal electrode based on aluminum (Al). Furthermore, the effect of an added fluorosurfactant on the resulting contact properties was examined. The performance of n-type c-Si solar cells with a boron diffusion on the front was significantly increased when L-histidine and/or the fluorosurfactant was applied as a full-area back surface field. This improvement was attributed to the modification of the interface and the effective work function of the contact by the dipole material which was corroborated by numerical device simulations. For these solar cells, conversion efficiencies of 17.5% were obtained with open-circuit voltages (Voc) of 625mV and fill factors of 76.3%, showing the potential of organic interface dipoles for silicon organic heterojunction solar cells due to their simple formation by solution processing and their low thermal budget requirements.
Kenkmann, Thomas, Deutsch, Alex, Thoma, Klaus, Ebert, Matthias, Poelchau, Michael, Buhl, Elmar, Carl, Eva-Regine, Danilewsky, Andreas, Dresen, Georg, Dufresne, Anja, Durr, Nathanaël, Ehm, Lars, Grosse, Christian, Gulde, Max, Güldemeister, Nicole, Hamann, Christopher, Hecht, Lutz, Hiermaier, Stefan, Hoerth, Tobias, Kowitz, Astrid, Langenhorst, Falko, Lexow, Bernd, Liermann, Hanns-Peter, Luther, Robert, Mansfeld, Ulrich, Moser, Dorothee, Raith, Manuel, Reimold, Wolf Uwe, Sauer, Martin, Schäfer, Frank, Schmitt, Ralf Thomas, Sommer, Frank, Wilk, Jakob, Winkler, Rebecca, Wünnemann, Kai
Experimental impact cratering: A summary of the major results of the MEMIN research unit
2018 Meteoritics & planetary science, Band: 53, Nummer: 8, Seiten: 1543 - 1568
KurzfassungThis paper reviews major findings of the Multidisciplinary Experimental and Modeling Impact Crater Research Network (MEMIN). MEMIN is a consortium, funded from 2009 till 2017 by the German Research Foundation, and is aimed at investigating impact cratering processes by experimental and modeling approaches. The vision of this network has been to comprehensively quantify impact processes by conducting a strictly controlled experimental campaign at the laboratory scale, together with a multidisciplinary analytical approach. Central to MEMIN has been the use of powerful two‐stage light‐gas accelerators capable of producing impact craters in the decimeter size range in solid rocks that allowed detailed spatial analyses of petrophysical, structural, and geochemical changes in target rocks and ejecta. In addition, explosive setups, membrane‐driven diamond anvil cells, as well as laser irradiation and split Hopkinson pressure bar technologies have been used to study the response of minerals and rocks to shock and dynamic loading as well as high‐temperature conditions. We used Seeberger sandstone, Taunus quartzite, Carrara marble, and Weibern tuff as major target rock types. In concert with the experiments we conducted mesoscale numerical simulations of shock wave propagation in heterogeneous rocks resolving the complex response of grains and pores to compressive, shear, and tensile loading and macroscale modeling of crater formation and fracturing. Major results comprise (1) projectile–target interaction, (2) various aspects of shock metamorphism with special focus on low shock pressures and effects of target porosity and water saturation, (3) crater morphologies and cratering efficiencies in various nonporous and porous lithologies, (4) in situ target damage, (5) ejecta dynamics, and (6) geophysical survey of experimental craters.
Tucher Nico, Habtamu T. Gebrewold, Bläsi Benedikt
Field stitching approach for the wave optical modeling of black solicon structures
2018 Opt Express, Band: 26, Nummer: 22, Seite: A937
KurzfassungThe interest in black silicon structures as an anti-reflective interface at the front side of silicon solar cells increased strongly with the rise of diamond wire sawing. The application of optical modeling in order to predict optimal structure parameters could be highly valuable. However, due to the random nature of the structure as well as dimensions in the range of the wavelengths of interest, optical modeling is still a challenge. Within this work, the stitching method of rigorously calculated fields is extended and applied to a black silicon structure. A Fourier transform is used to determine the angular intensity distribution in the far field. In combination with the OPTOS formalism, this allows modeling of silicon substrates with black silicon front side and shows a reasonably good agreement with optical measurement results. Implementing the investigated structure into a solar cell configuration reveals not only a low reflectance but also a very good light trapping performance close to that of a Lambertian scatterer

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Hörsch J, Schäfer M, Becker S, Schramm S, Greiner M
Flow tracing as a tool set for the analysis of networked large-scale renewable electricity systems
2018 Int J Elec Power, Band: 96, Seiten: 390 - 397
KurzfassungThe method of flow tracing follows the power flow from net-generating sources through the network to the net-consuming sinks, which allows to assign the usage of the underlying transmission infrastructure to the system participants. This article presents a reformulation that is applicable to arbitrary compositions of inflow appearing naturally in models of large-scale electricity systems with a high share of renewable power generation. We propose an application which allows to associate power flows on the grid to specific regions or generation technologies, and emphasizes the capability of this technique to disentangle the spatio-temporal patterns of physical imports and exports occurring in such systems. The analytical potential of this method is showcased for a scenario based on the IEEE 118 bus network.
Tranberg B, Schwenk-Nebbe LJ, Schäfer M, Hörsch J, Greiner M
Flow-based nodal cost allocation in a heterogeneous highly renewable European electricity network
2018 Energy, Band: 150, Seiten: 122 - 133
KurzfassungFor a cost efficient design of a future renewable European electricity system, the placement of renewable generation capacity will seek to exploit locations with good resource quality, that is for instance onshore wind in countries bordering the North Sea and solar PV in South European countries. Regions with less favorable renewable generation conditions benefit from this remote capacity by importing the respective electricity as power flows through the transmission grid. The resulting intricate pattern of imports and exports represents a challenge for the analysis of system costs on the level of individual countries. Using a tracing technique, we introduce flow-based nodal levelized costs of electricity (LCOE) which allow to incorporate capital and operational costs associated with the usage of generation capacity located outside the respective country under consideration. This concept and a complementary allocation of transmission infrastructure costs is applied to a simplified model of an interconnected highly renewable European electricity system. We observe that cooperation between the European countries in a heterogeneous system layout does not only reduce the system-wide LCOE, but also the flow-based nodal LCOEs for every country individually.
A.Amado-Rey, Y.Campos-Roca, C.Friesicke, S.Wagner, O.Ambacher
GCPW GaAs Broadside Couplers at H-Band and Application to Balanced Power Amplifier
2018 IEEE T Microw Theory, Band: 67, Nummer: 1, Seiten: 78 - 85
M.Knapp, R.Hoffmann, V.Lebedev, V.Cimalla, O.Ambacher
Graphene as an active virtually massless top electrode for RF solidly mounted bulk acoustic wave (SMR-BAW) resonators
2018 Nanotechnology, Band: 29, Nummer: 10, Ergänzungsband: 105302
E.Derguti, E.Ture, S.Krause, D.Schwantuschke, R.Quay, O.Ambacher
High-Power Asymmetrical Three-Way GaN Doherty Power Amplifier at C-Band Frequencies
2018 2018 48th European Microwave Conference (EuMC), Madrid, Seiten: 1233 - 1236
Cariou Romain, Benick Jan, Feldmann Frank, Höhn Oliver, Hauser Hubert, Beutel Paul, Razek Nasser, Wimplinger Markus, Bläsi Benedikt, Lackner David, Hermle Martin, Siefer Gerald, Glunz Stefan, Bett Andreas, Dimroth Frank
III–V-on-silicon solar cells reaching 33% photoconversion efficiency in two-terminal configuration
2018 Nature Energy, Band: 3, Nummer: 4, Seite: 326–333
KurzfassungSilicon dominates the photovoltaic industry but the conversion efficiency of silicon single-junction solar cells is intrinsically constrained to 29.4%, and practically limited to around 27%. It is possible to overcome this limit by combining silicon with high-bandgap materials, such as III–V semiconductors, in a multi-junction device. Significant challenges associated with this material combination have hindered the development of highly efficient III–V/Si solar cells. Here, we demonstrate a III–V/Si cell reaching similar performances to standard III–V/Ge triple-junction solar cells. This device is fabricated using wafer bonding to permanently join a GaInP/GaAs top cell with a silicon bottom cell. The key issues of III–V/Si interface recombination and silicon's weak absorption are addressed using poly-silicon/SiOx passivating contacts and a novel rear-side diffraction grating for the silicon bottom cell. With these combined features, we demonstrate a two-terminal GaInP/GaAs//Si solar cell reaching a 1-sun AM1.5G conversion efficiency of 33.3%.
Richter Armin, Benick Jan, Fell Andreas, Hermle Martin, Glunz Stefan
Impact of bulk impurity contamination on the performance of high-efficiency n -type silicon solar cells
2018 Prog Photovoltaics, Band: 24, Nummer: 10, Seite: 1319
KurzfassungThe experimental variation of wafer thickness and resistivity at device level combined with a comprehensive device simulation study allows the identification of dominating recombinationinduced power loss mechanisms in high‐efficiency n‐type silicon solar cells (A. Richter et al, Sol. Energy Mater. Sol. Cells 173, p. 96, 2017). Under the assumption of specific Shockley‐Read‐Hall (SRH) recombination parameters, impurity recombination within the silicon bulk was identified as one main source for efficiency losses particularly for solar cells made of high‐resistivity silicon. In this work, we extend that analysis approach focusing on the SRH recombination parameters in order to investigate whether certain properties of these recombination‐active impurities can be identified using this kind of simulation‐based analysis. Reported SRH recombination parameters of various common impurities (eg, Fe, Cr, or Ni) were considered. It was found that a dominating role of certain impurities as Cu, Au, Co, or Zn can be excluded. A general simulation study as a function of the fundamental SRH recombination parameters allowed us to reduce the possible SRH parameters significantly in particular of the capture cross‐section ratio of electrons and holes. These results demonstrate that our analysis approach, which combines an experimental variation of wafer thickness and resistivity with a comprehensive device simulation, can provide deep insights into the solar cells loss mechanisms. In particular, the conclusions regarding SRH recombination are of importance for solar cells made of n‐type silicon as there are no meta‐stable impurity states formed that would allow a direct identification of impurity recombination–related power loss as reported for p‐type Si.
S.Moench, B.Weiss, R.Reiner, P.Waltereit, R.Quay, O.Ambacher, I.Kallfass et al.
Instabilities by Parasitic Substrate-Loop of GaN-on-Si HEMTs in Half-Bridges
2018 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA), Atlanta, GA, Seiten: 242 - 246
Reichel Christian, Reusch Markus, Kotula Stefan, Granek Filip, Richter Armin, Hermle Martin, Glunz Stefan
Insulating and passivating plasma-enhanced atomic layer deposited aluminum oxide thin films for silicon solar cells
2018 Thin Solid Films, Band: 656, Seite: 53–60
KurzfassungPlasma-enhanced atomic layer deposited (PEALD) aluminum oxide (Al2O3) thin film were investigated with respect to their application in silicon solar cells where not only excellent surface passivation but also excellent electrical insulation properties are required. In this study, the insulation properties of about 10 nm to almost 250 nm Al2O3 thin films, deposited at temperatures in the range of 100 °C to 350 °C and annealed in the range of 250 °C to 450 °C, were correlated to various thin film properties, most notably the thin film defect density, i. e. pinhole density, and the thin film stress. Al2O3 thin films provide sufficient electrical insulation after a postdeposition annealing step at 450 °C when deposited at 250 °C with thickness of at least 80 nm which can be attributed to a low defect density and low stress in the thin films, allowing a low leakage current density and a high breakdown voltage that was independent of the type of metals used for the electrode. Al2O3 thin films deposited and annealed at these temperatures enabled a very good surface passivation of silicon. These results indicate that Al2O3 thin films realized by PEALD are a promising candidate for silicon solar cells that rely on passivating as well as insulating thin films.
A. Ding, M. Reusch, Y. Lu, N. Kurz, R. Lozar, T. Christoph, R. Driad, O. Ambacher, A. Zukauskaite
Investigation of temperature characteristics and substrate influence on AlScN-based SAW resonators
2018 IEEE, Seiten: 1 - 9

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B.Gashi, S.Krause, R.Quay, C.Fager, O.Ambacher
Investigations of Active Antenna Doherty Power Amplifier Modules Under Beam-Steering Mismatch
2018 IEEE Microwave and Wireless Components Letters, Band: 99, Seiten: 1 - 3
Reiterer, A., Leidinger, M.
Laserscanner zur Lichtraummessung: Präzise messen, effizient auswerten
2018 EI - Der Eisenbahningenieur, Nummer: Mai 2018, Seiten: 44 - 47
Jörg Schube, Leonard Tutsch, Tobias Fellmeth, Martin Bivour, Frank Feldmann, Thibaud Hatt, Florian Maier, Roman Keding, Florian Clement, Stefan W Glunz
Low-Resistivity Screen-Printed Contacts on Indium Tin Oxide Layers for Silicon Solar Cells With Passivating Contacts
2018 IEEE J Photovolt
KurzfassungThe capability for contact formation on indium tin oxide layers of different low-temperature screen printing silver pastes after thermal curing and photonic sintering is evaluated in detail. The 80-nm-thick indium tin oxide layers used in this study are sputtered at three different oxygen gas flows and, consequently, differ by their electrical and optical properties. All pastes are analyzed by means of simultaneous thermogravimetry-differential scanning calorimetry. After printing and contact formation processing, the lateral resistivity of the metal contacts and their contact resistivity to the indium tin oxide layers are determined. Furthermore, the microstructure of the metal electrodes is investigated to gain a deeper understanding of the underlying contact formation mechanisms. Besides low-temperature curing at T curing,low = 180–220 °C, as conventionally applied to silicon heterojunction solar cells, photonic sintering and thermal curing at medium temperatures T curing,mid = 250–350 °C are utilized. The higher curing temperatures in the range of T curing,mid enhance the sintering and densification processes of the different pastes, and thereby, lateral resistivities of 2.4–3.5 μΩ⋅cm and contact resistivities of 1.0–2.5 mΩ⋅cm2 are achieved. The results indicate a promising industry-relevant non-firing-through metallization approach for, e.g., poly-silicon-based structures like tunnel oxide passivating contacts, which allow comparatively high temperatures for contact formation processing. With thermal curing at T curing,low and photonic sintering, both compatible with temperature-sensitive silicon heterojunction solar cells, lateral finger resistivities of 6.5–9.4 μΩ⋅cm and contact resistivities of 1.2–2.5 mΩ⋅cm2 are achieved. Thereby, photonic sintering has the potential of a significantly reduced process time from several minutes down to 1–4 ms.
Durr, Nathanael, Sauer, Martin, Hiermaier, Stefan
Mesoscale investigation of dynamic fracture in quartzite and sandstone and homogenization to macroscale
2018 Int J Solids Struct, Band: 144-145, Seiten: 160 - 179
KurzfassungThe work presented here is part of the MEMIN (Multidisciplinary Experimental and Modeling Impact Research Network) project, which is devoted to the experimental and numerical investigation of the effects of meteorite impact on geological materials from laboratory scale to natural scale. In general, high velocity impacts on rock material causes fractures in the target that may lead to spallation of material near surfaces. While spallation effects are of great importance for laboratory scale craters, they are much less significant in natural craters. Therefore, they need to be taken into account when comparing natural craters with laboratory craters, particularly, when scaling laws that provide relationships between laboratory and natural craters shall be developed. This scale bridging requires realistic quantification of spallation effects, which can be done with numerical methods if appropriate material models exist. For this purpose, we investigate dynamic fracture in quartzite and sandstone. We present a new methodology to derive three dimensional macroscale material data from one-dimensional dynamic fracture experiments, namely Hopkinson-Bar experiments in the spallation configuration, using a new mesoscale simulation model. Simulations are conducted with the in-house hydrocode SOPHIA. Mesoscopic material parameters are identified from a parameter study such that simulated macroscopic failure quantities conform to experimentally measured data. The calibrated mesoscale model is then subjected to a set of multiaxial load cases in order to derive macroscopic yield and failure parameters using averaging techniques. The results can be directly used to calibrate macroscale material models for dynamic fracture and will support the predictability of laboratory craters and, in particular, of spallation effects.
Fell Andreas, Schön Jonas, Müller Matthias, Wöhrle Nico, Schubert Martin, Glunz Stefan
Modeling Edge Recombination in Silicon Solar Cells
2018 IEEE Journal of Photovoltaics, Seite: 1–7
Fischer, Kai, Hiermaier, Stefan, Riedel, Werner, Haering, Ivo
Morphology dependent assessment of resilience for urban areas
2018 Sustainability, Band: 10, Seiten: 1 - 14
KurzfassungThe formation of new threats and the increasing complexity of urban built infrastructures underline the need for more robust and sustainable systems, which are able to cope with adverse events. Achieving sustainability requires the strengthening of resilience. Currently, a comprehensive approach for the quantification of resilience of urban infrastructure is missing. Within this paper, a new generalized mathematical framework is presented. A clear definition of terms and their interaction builds the basis of this resilience assessment scheme. Classical risk-based as well as additional components are aligned along the timeline before, during and after disruptive events, to quantify the susceptibility, the vulnerability and the response and recovery behavior of complex systems for multiple threat scenarios. The approach allows the evaluation of complete urban surroundings and enables a quantitative comparison with other development plans or cities. A comprehensive resilience framework should cover at least preparation, prevention, protection, response and recovery. The presented approach determines respective indicators and provides decision support, which enhancement measures are more effective. Hence, the framework quantifies for instance, if it is better to avoid a hazardous event or to tolerate an event with an increased robustness. An application example is given to assess different urban forms, i.e., morphologies, with consideration of multiple adverse events, like terrorist attacks or earthquakes, and multiple buildings. Each urban object includes a certain number of attributes, like the object use, the construction type, the time-dependent number of persons and the value, to derive different performance targets. The assessment results in the identification of weak spots with respect to single resilience indicators. Based on the generalized mathematical formulation and suitable combination of indicators, this approach can quantify the resilience of urban morphologies, independent of possible single threat types and threat locations.
R.Reiner, P.Waltereit, S.Moench, M.Dammann, B.Weiss, R.Quay, O.Ambacher
Multi-Stage Cascode in High-Voltage AlGaN/GaN-on-Si Technology
2018 Multi-Stage Cascode in High-Voltage AlGaN/GaN, Seiten: 237 - 241
Meßmer Christoph, Bivour Martin, Schon Jonas, Glunz Stefan, Hermle Martin
Numerical Simulation of Silicon Heterojunction Solar Cells Featuring Metal Oxides as Carrier-Selective Contacts
2018 IEEE Journal of Photovoltaics, Band: 8, Nummer: 2, Seite: 456–464
KurzfassungThe applicability of different high (low) work function contact materials for the formation of alternative passivating and hole (electron) selective contacts is currently re-explored for silicon solar cells. To assist the engineering of those contacts, which is still in its infancy, numerical device simulations are used to improve knowledge regarding relevant heterojunction and thin film properties with the focus on metal oxide based hole contacts. The importance of 1) a high metal oxide work function for the induced c-Si pn-junction is shown. It is elucidated that for an efficient hole transport from this induced c-Si junction into the external electrode, via the buffer and the metal oxide, 2) the metal oxide’s conduction band must be below the valence band of the buffer (or c-Si absorber) for direct band-to-band tunneling, or 3) bulk traps near the valence band edge of the buffer (or c-Si absorber) are needed for trap-assisted tunneling.
Tucher Nico, Höhn Oliver, Goldschmidt Jan Christoph, Bläsi Benedikt
Optical modeling of structured silicon-based tandem solar cells and module stacks
2018 Opt Express, Band: 26, Nummer: 18, Seiten: A761 - A768

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R.Reiner, B.Weiss, D.Meder, P.Waltereit, T.Gerrer, R.Quay, C.Vockenberger, O.Ambacher
PCB-Embedding for GaN-on-Si Power Devices and ICs
2018 CIPS 2018, 10th International Conference on Integrated Power Electronics Systems, Seiten: 1 - 6
Rauer Michael, Schmiga Christian, Glatthaar Markus, Glunz Stefan
Quantitative theoretical and experimental analysis of alloying from screen-printed aluminum pastes on silicon surfaces
2018 Solar Energy Materials and Solar Cells, Band: 176, Seite: 295–301
KurzfassungIn this study, we present detailed theoretical and experimental investigations on full-area alloying from screenprinted aluminum pastes on silicon surfaces for solar cell applications. We introduce a simple analytical model for the description of the alloying process derived from existing models for evaporated Al layers, which we adapt to printed Al pastes. Thereby, we particularly account for the recrystallization of Si within the paste particles, which we refer to as parasitic Si recrystallization. Applying our model, we demonstrate good accordance of calculated with measured eutectic layer thicknesses. We show that the model can be versatilely used to investigate screen-printed Al-alloyed contacts in detail: We demonstrate that the latent heat of the Al paste significantly influences the alloying process. Thus, the effective peak temperature of the alloying process can be several 100 °C below the set peak temperature of the firing furnace. By combining calculations of the effective peak temperature with measurements of the Al doping concentration, we determine a parameterization of the solid solubility of Al in Si down to the eutectic temperature of 577 °C. Our investigations therefore provide improved understanding of alloying from printed Al pastes and enable the specific optimization of Al-alloyed contacts.
F.Heinz, D.Schwantuschke, A.Leuther, A.Tessmann, M.Ohlrogge, R.Quay, O.Ambacher
RF-Noise Modeling of InGaAs Metamorphic HEMTs and MOSFETs
2018 2018 13th European Microwave Integrated Circuits Conference (EuMIC), Madrid, Seiten: 150 - 153
Meßmer Christoph, Bivour Martin, Schön Jonas, Hermle Martin
Requirements for efficient hole extraction in transition metal oxide-based silicon heterojunction solar cells
2018 J Appl Phys, Nummer: 124, Seiten: 085702-1 - 085702-8

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M.Weiß, C.Friesicke, R.Quay, O.Ambacher
Riemann-Pump based RF-Power DACs in GaN Technology for 5G Base Stations
2018 IEEE MTT-S International Microwave Workshop Series on 5G Hardware and System Technologies (IMWS-5G), Dublin, Seiten: 1 - 3
Glunz Stefan, Feldmann Frank
SiO 2 surface passivation layers – a key technology for silicon solar cells
2018 Solar Energy Materials and Solar Cells, Band: 185, Seite: 260–269
KurzfassungHigh-efficiency silicon solar cells strongly rely on an effective reduction of charge carrier recombination at their surfaces, i.e. surface passivation. Today's industrial silicon solar cells often utilize dielectric surface passivation layers such as SiNx and Al2O3. However, a passivation layer well-known from the microelectronic industry, SiO2, had and has a strong impact on silicon photovoltaics. It allowed to develop the first 20% efficient silicon solar cells in the past and currently experiences a renaissance as the interfacial oxide for silicon-based passivating contacts, thus enabling the next generation of silicon solar cells. This article reviews the properties of SiO2 passivation layers and their strong impact on the historical and current development of silicon solar cells.
B.Amado-Rey, A.Tessmann, Y.Campos.Roca, H.Massler, A.Leuther, O.Ambacher
Spurious Mode Suppression in the Design of GCPW Submillimeter-wave Power Amplifiers
2018 48th European Microwave Conference (EuMC), Madrid, Seiten: 851 - 854
KurzfassungB. Amado-Rey, A. Tessmann, Y. Campos-Roca, H. Massler, A. Leuther and O. Ambacher, Spurious Mode Suppression in the Design of GCPW Submillimeter-wave Power Amplifiers (2018), 2018 48th European Microwave Conference (EuMC), Madrid, pp. 851-854. doi: 10.23919/EuMC.2018.8541553
F.van Raay, D.Schwantuschke, A.Leuther, P.Brückner, D.Peschel, R.Quay, M.Schlechtweg, O.Ambacher
State Dependency, Low-Frequency Dispersion, and Thermal Effects in Microwave III-V HEMTs
2018 13th European Microwave Integrated Circuits Conference (EuMIC), Madrid, Seiten: 1 - 225
F. Balle, T. Beck, D. Eifler, J.H. Fitschen, S. Schuff, G. Steidl
Strain analysis by a total generalized variation regularized optical flow model
2018 Inverse Probl Sci En

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M.Reusch, K.Holc, V.Lebedev, N.Kurz, A.Zukauskaite, O.Ambacher
Temperature Cross-sensitivity of AlN-based Flexural Plate Wave Sensors
2018 IEEE Sens J, Band: 18, Nummer: 19, Seiten: 7810 - 7818
N.Kurz, Y.Lu, L.Kirste, M.Reusch, A.Žukauskaitė, V.Lebedev, O.Ambacher
Temperature Dependence of the Pyroelectric Coefficient of AlScN Thin Films
2018 Phys Status Solidi A, Band: 215, Nummer: 13, Ergänzungsband: 1700831
Höhn Oliver, Tucher Nico, Bläsi Benedikt
Theoretical study of pyramid sizes and scattering effects in silicon photovoltaic module stacks
2018 Opt Express, Band: 26, Nummer: 6, Seiten: A320 - A330
KurzfassungFront side pyramids are the industrial standard for wafer based monocrystalline silicon solar cells. These pyramids fulfill two tasks: They act as anti-reflective structure on the one hand and as a light-trapping structure on the other hand. In recent development smaller pyramids with sizes below 1 μm attract more and more interest. In this paper an optical analysis of periodically arranged front side pyramids is performed. The impact on the reflectance as well as on the useful absorption within the solar cell is investigated depending on the pyramids size, the amount of additional scattering in the system and the quality of the rear side reflector. In contrast to other investigations not only the solar cell, but the full photovoltaic (PV) module stack is considered. This can strongly influence results, as we show in this paper. The results indicate that in a PV module stack with realistic assumptions for the amount of scattering as well as for the rear side reflectance only small differences for pyramids with sizes above 600 nm occur. Preliminary conclusions for random pyramids deduced from these results for periodically arranged pyramids indicate that these differences could become even smaller.

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S.Moench, R.Reiner, B.Weiss, P.Waltereit, R.Quay, T.Kaden, O.Ambacher, I.Kallfass
Towards Highly-Integrated High-Voltage Multi-MHz GaN-on-Si Power ICs and Modules
2018 PCIM Europe 2018; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management

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Florian Schindler, Andreas Fell, Ralph Müller, Jan Benick, Armin Richter, Frank Feldmann, Patricia Krenckel, Stephan Riepe, Martin C Schubert, Stefan W Glunz
Towards the efficiency limits of multicrystalline silicon solar cells
2018 Sol Energ Mat Sol C, Band: 185, Seiten: 198 - 204
KurzfassungIn this contribution, we present our recent results for high efficiency multicrystalline silicon solar cells. Based on n-type high-performance multicrystalline silicon substrates in combination with the TOPCon solar cell concept featuring a full area passivating back contact and a boron-diffused emitter as well as a plasma-etched black-silicon texture at the front side, a certified conversion efficiency of 22.3% has been achieved, which is currently the world record efficiency for multicrystalline silicon solar cells. A detailed loss analysis of the record solar cell batch discloses the nature of the remaining loss mechanisms, revealing the route for further improvements. We observe an efficiency gap between the multicrystalline and the FZ reference solar cells of ~1%abs. Compared to the FZ reference cells, the mc-Si cells also feature a significantly larger scattering in Voc and Jsc as well as a fill factor loss of ~1.5%abs. We show that the scattering in Jsc correlates with the area fraction of recombination-active structural crystal defects and the scattering in Voc additionally with lateral emitter-induced inhomogeneities. The fill factor loss is attributed to the general presence of strongly recombination-active grain boundaries. A detailed loss analysis of the record mc-Si solar cell shows that the major electrical losses are due to recombination at grain boundaries (0.7%abs) and recombination in the emitter (0.6%abs). By reducing these electrical loss channels, e.g. by an improved crystallization process together with a hydrogenation of the bulk and application of an adapted emitter, we expect to reach efficiencies for mc-Si solar cells in the range of 23%.
Schindler Florian, Fell Andreas, Müller Ralph, Benick Jan, Richter Armin, Feldmann Frank, Krenckel Patricia, Riepe Stephan, Schubert Martin, Glunz Stefan
Towards the efficiency limits of multicrystalline silicon solar cells
2018 Solar Energy Materials and Solar Cells, Band: 185, Seite: 198–204
KurzfassungIn this contribution, we present our recent results for high efficiency multicrystalline silicon solar cells. Based on n-type high-performance multicrystalline silicon substrates in combination with the TOPCon solar cell concept featuring a full area passivating back contact and a boron-diffused emitter as well as a plasma-etched blacksilicon texture at the front side, a certified conversion efficiency of 22.3% has been achieved, which is currently the world record efficiency for multicrystalline silicon solar cells. A detailed loss analysis of the record solar cell batch discloses the nature of the remaining loss mechanisms, revealing the route for further improvements. We observe an efficiency gap between the multicrystalline and the FZ reference solar cells of ~1%abs. Compared to the FZ reference cells, the mc-Si cells also feature a significantly larger scattering in Voc and Jsc as well as a fill factor loss of ~1.5%abs. We show that the scattering in Jsc correlates with the area fraction of recombinationactive structural crystal defects and the scattering in Voc additionally with lateral emitter-induced inhomogeneities. The fill factor loss is attributed to the general presence of strongly recombination-active grain boundaries. A detailed loss analysis of the record mc-Si solar cell shows that the major electrical losses are due to recombination at grain boundaries (0.7%abs) and recombination in the emitter (0.6%abs). By reducing these electrical loss channels, e.g. by an improved crystallization process together with a hydrogenation of the bulk and application of an adapted emitter, we expect to reach efficiencies for mc-Si solar cells in the range of 23%.
T. Gerrer, V. Cimalla, P. Waltereit, S. Müller, F. Benkhelifa, T. Maier, H. Czap, O. Ambacher, R. Quay
Transfer of AlGaN/GaN RF-devices onto diamond substrates via van der Waals bonding
2018 Int J Microw Wirel T, Band: 10, Nummer: 5-6, Seiten: 666 - 673
F. Lionetto, C. Mele, P. Leo, S. D'Ostuni, F. Balle, A. Maffezzoli
Ultrasonic spot welding of carbon fiber reinforced epoxy composites to aluminum: mechanical and electrochemical characterization
2018 Compos Part B-eng, Band: 144, Seiten: 134 - 142
Haering, Ivo, Ramin, Malte vo, Stottmeister, Alexander, Schaefer, Johannes, Vogelbacher, Georg, Brombacher, Bernd, Pfeiffer, Mercy, Restayn, Elena-Maria, Ross, Katharina, Schneider, Johannes, Hiermaier, Stefan
Validated 3D spatial stepwise quantitative hazard, risk and resilience analysis and management of explosive events in urban areas
2018 European Journal of security research, Band: Online First, Seiten: 1 - 37
KurzfassungUrban physical security and resilience with respect to accidental and intentional explosive events are an increasing issue regarding civil safety and security of modern societies and their citizens. Examples include industrial on-site explosions, gas explosions or terrorist attacks. In particular, multiple, simultaneous and maliciously time-coordinated events are an increasing event type such as complex attack events consisting of targeted combinations of improvised explosive devices. The paper presents a comprehensive, tailorable and stepwise process. This includes methodologies for scenario, hazard, damage, exposure, event frequency, risk and resilience analysis that have been developed, refined and praxis-tested over decades. The focus is on a summarizing description of the modern best practice approach, the validation efforts undertaken for each step as well as two detailed case studies for exemplary presentation and overall validation. In a comprehensive table, the present approach is compared with other state-of-the-art approaches. The paper shows a refined process how to systematically improve resilience when using the tool, in particular through barriers at explosive sites and at exposed sites of various geometries. Furthermore, along the presentation a set of quality requirements regarding explosive event risk and resilience analyses are provided as collected over the years from the in-field, user group and engineering science perspective as well as a broad outlook on extension options for the future.
T. Kemmer, M. Dammann, M. Baeumler, P. Brückner, H. Konstanzer, R. Quay, O. Ambacher
Voltage-and Temperature-Dependent Degradation of AIN/GaN High Electron Mobility Transistors
2018 International Integrated Reliability Workshop (IIRW), South Lake Tahoe, USA, Seiten: 1 - 6
F.Thome, E.Ture, P.Brueckner, R.Quay, O.Ambacher
W-band SPDT switches in planar and tri-gate 100-nm gate-length GaN-HEMT technology
2018 11th German Microwave Conference (GeMiC), Seiten: 331 - 334

2017

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B.Godejohann, E.Ture, S.Mueller, M.Prescher, L.Kirste, R.Aidam
AlN/GaN HEMTs grown by MBE and MOCVD: Impact of Al distribution
2017 Phys Status Solidi B, Band: 254, Nummer: 8, Ergänzungsband: 1600715
F.Thome, O.Ambacher
A 50-nm gate-length metamorphic HEMT distributed power amplifier MMIC based on stacked-HEMT unit cells
2017 IEEE MTT-S International Microwave Symposium (IMS), Seiten: 1695 - 1698
Durr, Nathanael, Sauer, Martin, Hiermaier, Stefan
A numerical study on mesoscale simulation of quartzite and sandstone under shock loading
2017 International Journal of Impact Engineering, Band: 108, Seite: 16
KurzfassungIn this paper, we present two numerical models for the mesoscale (grain scale) simulation of planar shock waves in quartzite and sandstone using the in-house hydrocode SOPHIA. The models are compared in terms of their capability to represent physical mechanisms, such as phase transitions in quartz and pore collapse in sandstone, and they are validated by comparison to literature data. The study is part of the MEMIN (Multidisciplinary Experimental and Modeling Impact Research Network) project, which is devoted to the experimental and numerical investigation of the effects of meteorite impact on geological materials from laboratory scale to natural scale. The first model is based on the Smoothed Particle Hydrodynamics (SPH) method. Simulations with rather simplified structures in planar symmetry are presented. The model is used to investigate basic effects of porosity, pore geometry and water saturation. The second model presented is a more detailed, three-dimensional Finite Element (FE) model. With this model, the effects of grain anisotropy and different types of shear strength modeling are studied. In a parameter study, we investigate the influence of these parameters on shock Hugoniot relations, such as shock velocity (Us) vs. particle velocity (Up) and compressive longitudinal stress (sL) vs. Up. Finally, the models are compared and the specific advantages and disadvantages of the different modeling variants are outlined.
Ganzenmueller, Georg, Blaum, E., Mohrmann, Deborah, Langhof, T., Plappert, D., Ledford, Noah, Paul, Hanna, Hiermaier, Stefan
A simplified design for a Split-Hopkinson tension bar with long pulse duration
2017 Procedia Engineering, Band: 197, Seiten: 109 - 118
KurzfassungThis paper presents a simplified design for a Split-Hopkinson Tension Bar (SHTB) which allows for pulse durations exceeding one millisecond. This testing apparatus is intended for material characterization requiring large amounts of elongation, necessitated either by large specimen dimensions, or large strains to failure. The design proposed here can be assembled from off the shelve components without the need for specialized machining tools. The simple mechanical design is accompanied by a comparatively low-cost, yet high-speed, means of independently measuring specimen strain using a fast line scan camera. The performance of this SHTB implementation is demonstrated by obtaining intermediate strain rate results for tensile yield strength of Polycarbonate in an unprecedented quality.
Ganzenmueller, Georg, Blaum, E., Mohrmann, Deborah, Langhof, T., Plappert, D., Ledford, Noah, Paul, Hanna, Hiermaier, Stefan
A simplified design for a Split-Hopkinson tension bar with long pulse duration
2017 Procedia Engineering, Band: 197, Seiten: 109 - 118
KurzfassungThis paper presents a simplified design for a Split-Hopkinson Tension Bar (SHTB) which allows for pulse durations exceeding one millisecond. This testing apparatus is intended for material characterization requiring large amounts of elongation, necessitated either by large specimen dimensions, or large strains to failure. The design proposed here can be assembled from off the shelve components without the need for specialized machining tools. The simple mechanical design is accompanied by a comparatively low-cost, yet high-speed, means of independently measuring specimen strain using a fast line scan camera. The performance of this SHTB implementation is demonstrated by obtaining intermediate strain rate results for tensile yield strength of Polycarbonate in an unprecedented quality.
Stemmler, S., Weinacker, H., Reiterer, A., Koch, B.
Algorithms for the Automatic Detection of Leaf Disturbances -A Geometrical Feature Extraction for Assessing Single Leaf States Algorithmen für die automatische Erkennung von Blattstörungen - eine geometrische Merkmalsextraktion zur Bewertung der Zustände einzelner Blätter
2017 avn Allgemeine Vermessungsnachrichten, Nummer: 11-12/2017, Seiten: 370 - 377
J.Stehle, A.K.Samaro, U.Krishnamoorathy, O.Ambacher
Atomic layer deposited P-type nickel oxide and cobalt oxide for ethanol gas sensing
2017 19th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), Kaohsiung, Seiten: 1504 - 1507
F.Thome, A.Leuther, M.Schlechtweg, O.Ambacher
Broadband High-Power W-Band Amplifier MMICs Based on Stacked-HEMT Unit Cells
2017 IEEE T Microw Theory, Band: 66, Nummer: 3, Seiten: 1312 - 1318
F.Thome, A.Leuther, H.Massler, M.Schlechtweg, O.Ambacher
Comparison of a 35-nm and a 50-nm gate-length metamorphic HEMT technology for millimeter-wave low-noise amplifier MMICs
2017 IEEE MTT-S International Microwave Symposium (IMS), Seiten: 752 - 755
Schäfer M, Tranberg B, Hempel S, Schramm S, Greiner M
Decompositions of injection patterns for nodal flow allocation in renewable electricity networks
2017 Eur Phys J B, Band: 90, Seite: 144
KurzfassungThe large-scale integration of fluctuating renewable power generation represents a challenge to the technical and economical design of a sustainable future electricity system. In this context, the increasing significance of long-range power transmission calls for innovative methods to understand the emerging complex flow patterns and to integrate price signals about the respective infrastructure needs into the energy market design. We introduce a decomposition method of injection patterns. Contrary to standard flow tracing approaches, it provides nodal allocations of link flows and costs in electricity networks by decomposing the network injection pattern into market-inspired elementary import/export building blocks. We apply the new approach to a simplified data-driven model of a European electricity grid with a high share of renewable wind and solar power generation.
E.Ture, M.Musser, A.Huelsmann, R.Quay, O.Ambacher
Demonstration of an RF front-end based on GaN HEMT technology
2017 Sensors, and Command, Control, Communications, and Intelligence, Band: 10184
M.Weiss, C.Friesicke, T.Metzger, E.Schmidhammer, R.Quay, O.Ambacher
Design, Realization, and Evaluation of a Riemann Pump in GaN Technology
2017 IEEE Microw Wirel Co, Band: 27, Nummer: 7, Seiten: 672 - 674
J.Stehle, A.K.Samarao, G.Yama, U.Krishnamoorthy, O.Ambacher
Development of a Silicon-Only Capacitive Dew Point Sensor
2017 IEEE Sens J, Band: 17, Nummer: 22, Seiten: 7223 - 7230
Wagner Lukas, Mundt Laura, Mathiazhagan Gayathri, Mundus Markus, Schubert Martin, Mastroianni Simone, Würfel Uli, Hinsch Andreas, Glunz Stefan
Distinguishing crystallization stages and their influence on quantum efficiency during perovskite solar cell formation in real-time
2017 Scientific Reports, Band: 7, Nummer: 1, Seite: 14899
KurzfassungRelating crystallization of the absorber layer in a perovskite solar cell (PSC) to the device performance is a key challenge for the process development and in-depth understanding of these types of high efficient solar cells. A novel approach that enables real-time photo-physical and electrical characterization using a graphite-based PSC is introduced in this work. In our graphite-based PSC, the device architecture of porous monolithic contact layers creates the possibility to perform photovoltaic measurements while the perovskite crystallizes within this scaffold. The kinetics of crystallization in a solution based 2-step formation process has been analyzed by real-time measurement of the external photon to electron quantum efficiency as well as the photoluminescence emission spectra of the solar cell. With this method it was in particular possible to identify a previously overlooked crystallization stage during the formation of the perovskite absorber layer. This stage has significant influence on the development of the photocurrent, which is attributed to the formation of electrical pathways between the electron and hole contact, enabling efficient charge carrier extraction. We observe that in contrast to previously suggested models, the perovskite layer formation is indeed not complete with the end of crystal growth.
S.Moench, R.Reiner, B.Weiss, P.Waltereit, R.Quay, O.Ambacher, I.Kallfass
Effect of substrate termination on switching loss and switching time using 600 V GaN-on-Si HEMTs with integrated gate driver in half-bridges
2017 5th Workshop on Wide Bandgap Power Devices and Applications, Seiten: 257 - 264
Heinz Friedemann, Niewelt Tim, Schubert Martin
Experimental evidence of electron capture and emission from trap levels in Cz silicon
2017 physica status solidi (a), Band: 214, Nummer: 7, Seite: 1700292
KurzfassungUp to now the existence of trap levels − defect levels in the forbidden band gap which temporary trap minority charge carriers − in Cz silicon was controversially discussed. We directly monitor the transient dynamics of the free electron density in the conduction band by the means of a time correlated single photon counting of photoluminescence. A variation of the experimental conditions reveals both a decrease of the electron density on a timescale of microseconds, which is not governed by recombination and an apparent generation of electrons on a scale of up to multiple seconds. We discuss that the transient dynamics may be excellently described by trap levels, providing strong evidence for their existence.
Dlugosch, Michael, Fritsch, Jens, Lukaszewicz, Dirk, Hiermaier, Stefan
Experimental investigation and evaluation of numerical modeling approaches for hybrid-FRP-steel sections under impact loading for the application in automotive crash-structures
2017 Composite structures, Band: 174, Seiten: 338 - 347
KurzfassungA large body of work has studied the energy absorption of metallic and composite tubes undergoing crushing. Similarly, reinforcements of metallic structures with composites have also been studied. By contrast, composite tubes with metallic reinforcements (composite-intensive) have not been investigated, although they may offer benefits in terms of robustness or cost over both composite as well as metallic tubes. Here, composite materials with metallic reinforcements were tested under dynamic axial loading in order to study the effects of major design parameters on the energy absorption and load uniformity behavior. Significant benefits could be identified, particularly when considering cost aspects. Two numerical approaches for modeling the adhesive interface between the two discrete material phases were evaluated in terms of accuracy and efficiency in crash simulations. The simplified modeling technique comprising two layers of shell elements rigidly tied at the interface proved to be generally applicable to the evaluation of structural concepts in an early vehicle development stage.
Meier Sebastian, Maier Stefan, Demberger Carsten, Wolf Andreas, Biro Daniel, Glunz Stefan
Fast Co-Diffusion Process for Bifacial n-Type Solar Cells
2017 Solar RRL, Band: 1, Nummer: 1
Eberle Rebekka, Kwapil Wolfram, Schindler Florian, Glunz Stefan, Schubert Martin
Firing temperature profile impact on light induced degradation in multicrystalline silicon
2017 Energy Procedia, Band: 124, Seite: 712–717
E.Ture, P.Brueckner, M.Alsharef, R.Granzner, F.Schwierz, R.Quay, O.Ambacher
First demonstration of W-band Tri-gate GaN-HEMT power amplifier MMIC with 30 dBm output power
2017 IEEE MTT-S International Microwave Symposium (IMS), Seiten: 35 - 37
M.Reusch, K.Hole, A.Žukauskaitė, V.Lebedev, N.Kurz, O.Ambacher
Flexural plate wave sensors with buried IDT for sensing in liquids
2017 IEEE Sens J, Seiten: 1 - 3
Watson, Erkai, Gulde, Max, Hiermaier, Stefan
Fragment tracking in hypervelocity impact experiments
2017 Procedia Engineering, Band: 204, Seiten: 170 - 177
KurzfassungSpace debris impacts of in-orbit satellites cause varying degrees of fragmentation, ranging from minor damage to catastrophic breakup. In this paper, we introduce an experimental measurement approach for studying the fragmentation effects of hypervelocity impact in the laboratory. We demonstrate this method by investigating a hypervelocity impact on a thin aluminum bumper plates and tracking individual fragments in the debris clouds. The setup involves a thin laser plane illuminating the debris cloud fragments, which are recorded with a high-speed video camera. The image sequence is analyzed, yielding spatio-temporal information about each fragment in the debris cloud. This allows individual fragment size and velocity information, previously not available, to be calculated.
Watson, Erkai, Gulde, Max, Hiermaier, Stefan
Fragment tracking in hypervelocity impact experiments
2017 Procedia Engineering, Band: 204, Seiten: 170 - 177
KurzfassungSpace debris impacts of in-orbit satellites cause varying degrees of fragmentation, ranging from minor damage to catastrophic breakup. In this paper, we introduce an experimental measurement approach for studying the fragmentation effects of hypervelocity impact in the laboratory. We demonstrate this method by investigating a hypervelocity impact on a thin aluminum bumper plates and tracking individual fragments in the debris clouds. The setup involves a thin laser plane illuminating the debris cloud fragments, which are recorded with a high-speed video camera. The image sequence is analyzed, yielding spatio-temporal information about each fragment in the debris cloud. This allows individual fragment size and velocity information, previously not available, to be calculated.
Benick Jan, Richter Armin, Muller Ralph, Hauser Hubert, Feldmann Frank, Krenckel Patricia, Riepe Stephan, Schindler Florian, Schubert Martin, Hermle Martin, Bett Andreas, Glunz Stefan
High-Efficiency n-Type HP mc Silicon Solar Cells
2017 IEEE Journal of Photovoltaics, Band: 7, Nummer: 5, Seiten: 1171 - 1175
F.Thome, O.Ambacher
Highly Isolating and Broadband Single-Pole Double-Throw Switches for Millimeter-Wave Applications Up to 330 GHz
2017 IEEE T Microw Theory, Band: 66, Nummer: 4, Seiten: 1998 - 2009
Schindler Florian, Michl Bernhard, Krenckel Patricia, Riepe Stephan, Benick Jan, Müller Ralph, Richter Armin, Glunz Stefan, Schubert Martin
How to achieve efficiencies exceeding 22% with multicrystalline n-type silicon solar cells
2017 Energy Procedia, Band: 124, Seite: 777–780
Hoerth, T., Bagusat, F., Hiermaier, S.
Hugoniot data of Seeberger sandstone up to 7 GPa
2017 International Journal of Impact Engineering, Band: 99, Seiten: 122 - 130
KurzfassungPlanar-plate impact tests were carried out for the measurement of Hugoniot data of dry Seeberger sandstone in the pressure range of up to 7 GPa. A special inverse testing method suitable for rock targets was applied together with a laser interferometer for the measurement of the free-surface velocity of the target plate required for the calculation of the particle velocity (up) and the shock wave velocity (US) in the sandstone specimen. In our measurement range (impact velocity between about 50m/s and about 1300 m/s), the US - up data show significant scattering. The travel times of the impact-induced shock waves indicate that pore crushing occurs. A strong dependance of the US - up data on the test batch selected for the impact experiments and, thus, on the mining location was observed. This dependance is greater than the scattering of the individual data sets.
F. Lionetto, F. Balle, A. Maffezzoli
Hybrid ultrasonic spot welding of aluminum to carbon fiber reinforced epoxy composites
2017 J Mater Process Tech, Band: 247, Seiten: 289 - 295
B. Hannemann, S. Backe, S. Schmeer, F. Balle, U.P. Breuer, J. Schuster
Hybridisation of CFRP by the use of continuous metal fibres (MCFRP) for damage tolerant and electrically conductive lightweight structures
2017 Compos Struct, Band: 172, Seiten: 374 - 382
Péntek, Q.;, Hein, S.;, Miernik, A.;, Reiterer, A.
Image-based 3D surface approximation of the bladder using structure-from-motion for enhanced cystoscopy based on phantom data
2017 Biomedical Engineering / Biomedizinische Technik
Reichel Christian, Müller Ralph, Feldmann Frank, Richter Armin, Hermle Martin, Glunz Stefan
Influence of the transition region between p- and n-type polycrystalline silicon passivating contacts on the performance of interdigitated back contact silicon solar cells
2017 Journal of Applied Physics, Band: 122, Nummer: 18, Seite: 184502
KurzfassungPassivating contacts based on thin tunneling oxides (SiOx) and n- and p-type semi-crystalline or polycrystalline silicon (poly-Si) enable high passivation quality and low contact resistivity, but the integration of these pþ/n emitter and nþ/n back surface field junctions into interdigitated back contact silicon solar cells poses a challenge due to high recombination at the transition region from p-type to n-type poly-Si. Here, the transition region was created in different configurations—(a) pþ and nþ poly-Si regions are in direct contact with each other (“pn-junction”), using a local overcompensation (counterdoping) as a self-aligning process, (b) undoped (intrinsic) poly-Si remains between the pþ and nþ poly-Si regions (“pin-junction”), and (c) etched trenches separate the pþ and nþ poly-Si regions (“trench”)—in order to investigate the recombination characteristics and the reverse breakdown behavior of these solar cells. Illumination- and injection-dependent quasisteady state photoluminescence (suns-PL) and open-circuit voltage (suns-Voc) measurements revealed that non-ideal recombination in the space charge regions with high local ideality factors as well as recombination in shunted regions strongly limited the performance of solar cells without a trench. In contrast, solar cells with a trench allowed for open-circuit voltage (Voc) of 720 mV, fill factor of 79.6%, short-circuit current (Jsc) of 41.3 mA/cm2, and a conversion efficiencies (g)of 23.7%, showing that a lowly conducting and highly passivating intermediate layer between the pþ and nþ poly-Si regions is mandatory. Independent of the configuration, no hysteresis was observed upon multiple stresses in reverse direction, indicating a controlled and homogeneously distributed breakdown, but with different breakdown characteristics.
T. Beck, M. Klein, M. Smaga, F. Balle, D. Eifler
Innovative Experimental Approaches and Physical Measurement Methods for Fatigue Monitoring and Life Assessment
2017 Materials Science Forum, Band: 879, Seiten: 205 - 210
Meier Sebastian, Saint-Cast Pierre, Wöhrle Nico, Fell Andreas, Greulich Johannes, Wolf Andreas, Glunz Stefan
Internal resistance of rear totally diffused solar cells with line shaped contacts
2017 Journal of Applied Physics, Band: 122, Nummer: 18, Seite: 183102
KurzfassungWe present an analytical model for the internal resistance of passivated emitter and rear totally diffused (PERT) solar cells. First, we apply the model of Saint-Cast for the spreading resistance of a passivated emitter and rear cell (PERC) structure with line-shaped contacts. To account for the additional vertical current flow through the silicon wafer and the lateral current flow through the back surface field of a PERT structure, we add a parallel current path using common analytical expressions. We compare the analytical models with two-dimensional numerical simulations based on Quokka 3 and find deviations of less than 6% for the internal resistance. In addition, we compare the analytical model of the internal resistance of PERC and PERT solar cells with experimental data of the series resistance of PERC and PERT solar cells
R.Reiner, P.Waltereit, B.Weiss, R.Quay, O.Ambacher
Investigation of GaN-HEMTs in Reverse Conduction
2017 PCIM Europe; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Nuremberg, Germany, Seiten: 1 - 8
Kwapil Wolfram, Niewelt Tim, Schubert Martin
Kinetics of carrier-induced degradation at elevated temperature in multicrystalline silicon solar cells
2017 Solar Energy Materials and Solar Cells, Band: 173, Seite: 80–84
KurzfassungThe degradation kinetics of multicrystalline silicon solar cells and wafers at elevated temperature (often termed “LeTID”) depend on the specific temperature and injection conditions. We apply different forward biases in the dark at a constant temperature of ~75 °C to industrial passivated emitter rear contacted (PERC) solar cells fabricated on p-type multicrystalline wafers from a variety of material producers and determine the degradation rate constant in dependence of the excess carrier density at the p-n junction. We find that whereas the specific material properties influence the degradation extent, the degradation rate constant is comparable for all materials but depends on the excess carrier concentration. This implies involvement of one electron in the ratelimiting step of LeTID defect formation. The result not only is an important contribution to elucidate the physical mechanism underlying LeTID, but can also be used as a guideline for devising degradation tests of multicrystalline silicon wafers and solar cells.
Niewelt T., Selinger M., Grant N., Kwapil W., Murphy J., Schubert M.
Light-induced activation and deactivation of bulk defects in boron-doped float-zone silicon
2017 Journal of Applied Physics, Band: 121, Nummer: 18, Seite: 185702
KurzfassungIn this paper, we present new insight in the degradation and subsequent recovery of charge carrier lifetime upon light soaking at 75 °C observed in float-zone silicon wafers. Variations of doping type, dielectric passivation schemes and thermal treatments after layer deposition were performed. The degradation was only observed for p-type float-zone silicon wafers passivated with passivation schemes involving silicon nitride layers. An influence of thermal treatments after deposition was found. N-type wafers did not degrade independent of their passivation scheme. Room temperature re-passivation experiments showed the degradation to affect the wafer bulk, and photoluminescence studies demonstrated fine lateral striations of effective lifetime. We conclude that the degradation is caused by bulk defects that might be related to hydrogen complexes.
Niewelt Tim, Kwapil Wolfram, Selinger Marisa, Richter Armin, Schubert Martin
Long-Term Stability of Aluminum Oxide Based Surface Passivation Schemes Under Illumination at Elevated Temperatures
2017 IEEE Journal of Photovoltaics, Band: 7, Nummer: 5, Seite: 1197–1202
KurzfassungThe stability of passivation layers under the conditions of field application of solar modules is a crucial parameter. We have performed an experiment to test the stability of aluminum oxide based passivation schemes under halogen lamp illumination of 1 sun equivalent intensity at 75 °C. We compare aluminum oxide layers with atomic layer deposition and plasma-enhanced chemical vapor deposition with and without an amorphous silicon nitride capping layer. Different thermal treatments are performed to activate the passivation or simulate solar cell contact firing. All passivation schemes are tested on full four inch 1 Ω·cm p- and n-type float-zone silicon wafers. The quality and stability of the surface passivation are tested by means of repeated charge carrier lifetime measurements. No significant surface passivation degradation due to light-soaking is evident on capped samples for several hundred hours. N-type samples are demonstrated to maintain excellent passivation quality for at least 3700 h and only slight degradation of p-type samples is found.
Bett Alexander, Schulze Patricia, Winkler Kristina, Gasparetto Jacopo, Ndione Paul, Bivour Martin, Hinsch Andreas, Kohlstädt Markus, Lee Seunghun, Mastroianni Simone, Mundt Laura, Mundus Markus, Reichel Christian, Richter Armin, Veit Clemens, Wienands Karl, Würfel Uli, Veurman Welmoed, Glunz Stefan, Hermle Martin, Goldschmidt Jan
Low temperature perovskite solar cells with an evaporated TiO 2 compact layer for perovskite silicon tandem solar cells
2017 Energy Procedia, Band: 124, Seite: 567–576
Künzel T, Klumpp F, Weidlich A
Methodische Quantifizierung der Bereitstellungskosten flexibler Systemkomponenten im deutschen Stromsystem
2017 Zeitschrift für Energiewirtschaft, Band: 41, Nummer: 1, Seiten: 33 - 55
M.Reusch, S.Cherneva, Y.Lu, A.Žukauskaitė, L.Kirste, K.Holc, M.Datcheva
Microstructure and mechanical properties of stress-tailored piezoelectric AlN thin films for electro-acoustic devices
2017 Appl Surf Sci, Band: 407, Seiten: 307 - 314
Cariou Romain, Benick Jan, Beutel Paul, Razek Nasser, Flotgen Christoph, Hermle Martin, Lackner David, Glunz Stefan, Bett Andreas, Wimplinger Markus, Dimroth Frank
Monolithic two-terminal III–V//Si triple-junction solar cells with 30.2% efficiency under 1-Sun AM1.5g
2017 IEEE Journal of Photovoltaics, Band: 7, Nummer: 1, Seiten: 367 - 373
R.Reiner, P.Waltereit, B.Weiss, S.Moench, M.Wespel, S.Müller, R.Quay, O.Ambacher
Monolithically integrated power circuits in high-voltage GaN-on-Si heterojunction technology
2017 IET Power Electronics, Band: 11, Nummer: 4, Seiten: 681 - 688
V.Lebedev, T.Liser, T.Yoshikawa, M.Reusch, D. Iankov, C.Giese
Nanodiamond resonators fabricated on 8 ″Si substrates using adhesive wafer bonding
2017 J Micromech Microeng, Band: 27, Nummer: 6, Ergänzungsband: 065011
Mundt Laura, Heinz Friedemann, Albrecht Steve, Mundus Markus, Saliba Michael, Correa-Baena Juan, Anaraki Elham, Korte Lars, Gratzel Michael, Hagfeldt Anders, Rech Bernd, Schubert Martin, Glunz Stefan
Nondestructive probing of perovskite silicon tandem solar cells using multiwavelength photoluminescence mapping
2017 IEEE Journal of Photovoltaics, Band: 7, Nummer: 4, Seite: 1081–1086
KurzfassungIn this paper, spatially resolved photoluminescence (PL) spectroscopy with various excitation wavelengths is presented as a nondestructive and versatile technique providing access to the individual subcells of multijunction solar cells. This method is demonstrated on a state-of-the-art monolithic tandem solar cell composed of a planar perovskite solar cell and a silicon heterojunction solar cell. It is shown that the lateral distribution of inhomogeneities can be attributed unambiguously to the individual cells and be related to the manufacturing process. The approach of depth-selective probing of the silicon bottom cell is verified by comparison to reflection maps and by comparison to measurements of the silicon cell after removing the perovskite top cell. Analyzing subcells integrated into a monolithic tandem solar cell is challenging though crucial in order to identify performance limiting loss mechanisms. This method can be used to improve the study of the mutual influence of adjacent subcells in the fully fabricated device, which has been an unfeasible task up to now.
B.Weiss, R.Reiner, P.Waltereit, R.Quay, O.Ambacher
Operation of PCB-embedded, high-voltage multilevel-converter GaN-IC
2017 5th Workshop on Wide Bandgap Power Devices and Applications, Seiten: 398 - 403
Schindler Florian, Michl Bernhard, Krenckel Patricia, Riepe Stephan, Benick Jan, Müller Ralph, Richter Armin, Glunz Stefan, Schubert Martin
Optimized multicrystalline silicon for solar cells enabling conversion efficiencies of 22%
2017 Solar Energy Materials and Solar Cells, Band: 171, Seite: 180–186
KurzfassungMulticrystalline (mc) n-type silicon has proven to be a suitable substrate for the fabrication of highly efficient mc-Si solar cells. In this paper, we elaborate the impact of base material parameters on the efficiency potential of n-type mc-Si solar cells featuring a boron-diffused front side emitter and a full-area passivating rear contact (TOPCon). The electrical material quality can be significantly improved by replacing the standard crystallization process with a seed-assisted growth for crystallization of high-performance (HP) mc silicon. Using high-purity quartz crucibles or larger crucibles in combination with an optimization of the grain boundary area fraction with an adapted seed structure leads to further improvements of the material quality in terms of charge carrier lifetimes. However, not only the charge carrier lifetime, but also the base resistivity is of crucial importance for the efficiency potential depending on the cell concept. Based on experimental data and simulations, we assess the optimal range for the base resistivity and the wafer thickness for n-type mc-Si TOPCon solar cells. With the optimal material parameters, an “efficiency limiting bulk recombination analysis” (ELBA) reveals an efficiency potential in the range of 22.5% for n-type mc-Si TOPCon solar cells. Finally, we fabricated TOPCon solar cells based on optimized n-type HP mc-Si substrate and demonstrate a certified efficiency of 21.9%, which is the highest efficiency reported for multicrystalline silicon solar cells so far.
T.H. Loeber, B. Laegel, S. Wolff, S. Schuff, F. Balle, T. Beck, Dietmar Eifler, Jan Henrik Fitschen, Gabriele Steidl
Reducing curtaining effects in FIB/SEM applications by a goniometer stage and an image processing method
2017 J Vac Sci Technol B, Band: 35, Nummer: 6
S.Jauss, K.Hallaceli, S.Mansfeld, S.Schwaiger, W.Daves, O.Ambacher
Reliability analysis of LPCVD SiN gate dielectric for AlGaN/GaN MIS-HEMTs
2017 IEEE T Electron Dev, Band: 64, Nummer: 5, Seiten: 2298 - 2305
Schäfer M, Bugge Siggaard S, Zhu K, Risager Poulsen C, Greiner M
Scaling of transmission capacities in coarse-grained renewable electricity networks
2017 Epl-europhys Lett, Band: 119, Seite: 38004
KurzfassungNetwork models of large-scale electricity systems feature only a limited spatial resolution, either due to lack of data or in order to reduce the complexity of the problem with respect to numerical calculations. In such cases, both the network topology, the load and the generation patterns below a given spatial scale are aggregated into representative nodes. This coarse-graining affects power flows and thus the resulting transmission needs of the system. We derive analytical scaling laws for measures of network transmission capacity and cost in coarse-grained renewable electricity networks. For the cost measure only a very weak scaling with the spatial resolution of the system is found. The analytical results are shown to describe the scaling of the transmission infrastructure measures for a simplified, but data-driven and spatially detailed model of the European electricity system with a high share of fluctuating renewable generation.
Mundus M., Venkataramanachar Bhavana, Gehlhaar R., Kohlstädt M., Niesen B., Qiu Weiming, Herterich Jan, Sahli Florent, Brauninger M., Werner Jérémie, Hohl-Ebinger J., Uytterhoeven Griet, Würfel U., Ballif C., Schubert Martin, Warta W., Glunz Stefan
Spectrally resolved nonlinearity and temperature dependence of perovskite solar cells
2017 Solar Energy Materials and Solar Cells, Band: 172, Seite: 66–73
KurzfassungAn accurate electrical device characterization of hybrid organic-inorganic halide perovskite solar cells (PSCs) is an important prerequisite for further improvement and industrial transfer of this promising photovoltaic technology. In this work, we study the nonlinearity of current versus irradiance as well as the temperature dependence of PSCs in a spectrally resolved manner by highly accurate differential external quantum efficiency (EQE) measurements. We investigate three different types of PSCs fabricated by different research groups. The nonlinearity of all samples is found to be spectrally invariant, which significantly simplifies spectral mismatch corrections. We demonstrate that misinterpretation of EQE measurements can result in a more than 10% relative error in efficiency measurements, if solar simulators are adjusted to photocurrents determined from differential EQEs. For obtaining an accurate integrated photocurrent from EQEs, we introduce a new, convenient approach that accounts for cell nonlinearities but avoids the time-consuming full analysis of spectrally resolved nonlinearity. Moreover, for the samples investigated here, it is shown that the differential EQE measured at 0.35 suns bias irradiance represents a reasonably good estimate of the actual EQE at 1 sun. Furthermore, we determine spectrally resolved temperature coefficients (TCs) and show how the band gap blue shift varies with perovskite absorber and temperature.
Niewelt Tim, Kwapil Wolfram, Selinger Marisa, Richter Armin, Schubert Martin
Stability of effective lifetime of float-zone silicon wafers with AlO x surface passivation schemes under illumination at elevated temperature
2017 Energy Procedia, Band: 124, Seite: 146–151
B.Weiss, R.Reiner, V.Polyakov, P.Waltereit, R.Quay, O.Ambacher, D.Maksimović
Substrate biasing effects in a high-voltage, monolithically-integrated half-bridge GaN-Chip
2017 5th Workshop on Wide Bandgap Power Devices and Applications (WiPDA), Seiten: 265 - 272
Dlugosch, Michael, Volk, Maximilian, Lukaszewicz, Dirk, Fritsch, Jens, Hiermaier, Stefan
Suitability assessments for advanced composite-metal hybrid material systems in automotive crash structural applications
2017 International journal of automotive composites : IJAutoC, Band: 3, Seiten: 14 - 28
KurzfassungThe application of hybrid material systems composed of advanced composites and metals in automotive crash structural applications holds significant potential in terms of lightweighting and functional improvements. This paper proposes a comprehensive methodology to assess the suitability of vehicle body components for the application of hybrid material systems by analysing superimposed numerical crash simulation data of conventional steel bodies-in-white. The loading anisotropy and the global deformation are presented as two suitability criteria including an evaluation methodology to eventually select suitable hybrid material systems in the transition from conventional to enhanced material employment and vehicle structure design. Additionally, the methodology provides novel insights into the global structural loading by simultaneously considering multiple crash load cases.
Steinkemper Heiko, Geisemeyer Ino, Schubert Martin, Warta Wilhelm, Glunz Stefan
Temperature-dependent modeling of silicon solar cells—Eg, ni, recombination, and VOC
2017 IEEE Journal of Photovoltaics, Band: 7, Nummer: 2, Seite: 450–457
KurzfassungThe characterization and modeling of silicon solar cells under nonstandard conditions is an essential task in order to predict and optimize the annual yield when installed in the field. In this paper, focus is set on the temperature dependence of fundamental physical models for numerical device simulation of silicon solar cells. A wide range of industrially relevant solar cell concepts is simulated and compared to experimental data. The influence of fundamental physical models on the temperature dependence of the simulated devices is investigated. It is found that our simulations are in good agreement with experimental results for silicon solar cells that are limited by extrinsic defect or surface recombination. This is not the case for solar cells featuring carrier-selective contacts where intrinsic recombination processes, such as Auger recombination and radiative recombination, have a significant influence.
Haegel Nancy, Margolis Robert, Buonassisi Tonio, Feldman David, Froitzheim Armin, Garabedian Raffi, Green Martin, Glunz Stefan, Henning Hans-Martin, Holder Burkhard, Kaizuka Izumi, Kroposki Benjamin, Matsubara Koji, Niki Shigeru, Sakurai Keiichiro, Schindler Roland, Tumas William, Weber Eicke, Wilson Gregory, Woodhouse Michael, Kurtz Sarah
Terawatt-scale photovoltaics: Trajectories and challenges
2017 Science, Band: 356, Nummer: 6334, Seiten: 141 - 143
Fell Andreas, Schön Jonas, Schubert Martin, Glunz Stefan
The concept of skins for silicon solar cell modeling
2017 Solar Energy Materials and Solar Cells, Band: 173, Seite: 128–133
KurzfassungWithin (crystalline silicon) solar cell modeling, a skin means the thin region from the quasi-neutral bulk to the actual surface or metal contact, including e.g. doping profiles, induced band-bending or top-cells of a tandem configuration. A typical highly doped skin is commonly characterized by its main lumped properties: effective recombination via J0 and lateral conductance via Rsheet. When applied as a boundary condition to bulk carrier transport modeling, it is known as the conductive boundary model. However, the detailed resolution of physics inside the skin is then lacking but required in many cases, and possible complexities, like injection dependence of the lumped parameters, are commonly neglected. This work introduces a general parameterization of skins, which accounts fully for injection dependence and a vertical resistance, and is thus able to accurately describe arbitrarily complex skins by lumped parameters. A “skin solver” is implemented in the solar cell simulation software Quokka3 to solve a detailed skin in 1D and to perform the general parameterization. Additionally, the performance of the multidimensional quasi-neutral bulk (qn-bulk) solver is largely improved compared to Quokka2, enabling, for the first time, the 3D discretization and solution of up to an entire 156 mm × 156 mm solar cell in manageable computing times. Quokka3 can then consistently couple the skin solver with the qn-bulk solver. With this multiscale modeling approach, the user can define and solve a solar cell device including the details of the skins orders of magnitude faster compared to generic device simulation software, without loss of accuracy for the majority of conditions in wafer-based silicon solar cells. The new capabilities are demonstrated by showing how the front phosphorus diffusion of a PERC solar cell can be optimized with unprecedented completeness and accuracy. Besides accurately modeling 3D current transport in the bulk, the single solution domain intrinsically accounts for the busbar influence (both recombination and shading), the distributed resistance of the fingers, and the limited current collection independent of the surface area enlargement by texturing.
Richter Armin, Benick Jan, Müller Ralph, Feldmann Frank, Reichel Christian, Hermle Martin, Glunz Stefan
Tunnel oxide passivating electron contacts as full-area rear emitter of high-efficiency p-type silicon solar cells
2017 Progress in Photovoltaics: Research and Applications, Band: 107, Nummer: 23, Seite: 233506
KurzfassungTunnel oxide passivating contacts (TOPCon) consisting of an ultrathin tunnel oxide capped by a doped Si film exhibit excellent passivation and contact properties. The application of these contacts has so far resulted in efficiencies of up to 25.7% realized with an n‐type Si solar cell featuring a front‐side boron‐doped p+ emitter and n‐TOPCon as full‐area rear electron contact. In this work, we study the same cell structure on p‐type Si. In this case, the p+ diffusion on the front acts as a front surface field (FSF) and the n‐TOPCon layer as a full‐area rear emitter. One benefit of this rear‐junction cell design is that the whole base contributes to the hole transport towards the local contacts on the front, which means that the lateral current transport within the FSF is less important than in the case of the front emitter of the n‐type cell. To study this, we addressed the influence of the FSF lateral conductivity on the performance of these rear‐junction cells theoretically (based on a simulation study) as well as experimentally (with fabricated cells). Efficiencies up to 24.3% (independently confirmed) have been achieved with this structure applying a FSF and up to 23.9% without the full‐area FSF. As such, these results demonstrate a high device performance for theseTOPCon rear emitter cells even without a lateral conductivity in the FSF. This bears the potential to simplify the process chain quite substantially as no full‐area boron diffusion is required.
D. Weibel, F. Balle, D. Backe
Ultrasonic Fatigue of CFRP-Experimental Principle, Damage Analysis and Very High Cycle Fatigue Properties
2017 Key Engineering Materials, Band: 742, Seiten: 621 - 628
Niewelt Tim, Schindler Florian, Kwapil Wolfram, Eberle Rebekka, Schön Jonas, Schubert Martin
Understanding the light-induced degradation at elevated temperatures: Similarities between multicrystalline and floatzone p-type silicon.
2017 Progress in Photovoltaics: Research and Applications, Band: 99, Seite: 13701
KurzfassungThis paper discusses degradation phenomena in crystalline silicon. We present new investigations of the light‐ and elevated temperature‐induced degradation of multicrystalline silicon. The investigations provide insights into the defect parameters as well as the diffusivity and solubility of impurity species contributing to the defect. We discuss possible defect precursor species and can rule out several metallic impurities. We find that an involvement of hydrogen in the defect could explain the characteristic observations for light‐ and elevated temperature‐induced degradation. Furthermore, we demonstrate analogies to the light‐induced degradation mechanisms at elevated temperatures observed in floatzone silicon, where several experimental results also indicate an involvement of hydrogen in the defect. Based on the similarities between multicrystalline and floatzone silicon, we suggest that both degradation phenomena might be caused by the same or similar defects. As we do not expect large concentrations of metals in floatzone silicon, we suggest that complexes of hydrogen and a species introduced during crystal growth might cause both degradation phenomena.
D.Bleh, M.Rosch, M.Kuri, A.Dyck, A.Tessmann, A.Leuther, S.Wagner, B.Weismann-Thaden, H.P.Stulz, M.Zink, M.Riessle, R.Sommer, J.Wilcke, M.Schlechtweg, B.Yang, O.Ambacher
W-band time-domain multiplexing FMCW MIMO radar for far-field 3-D imaging
2017 IEEE T Microw Theory, Seiten: 1 - 11
M.Knapp, R.Hoffmann, V.Cimalla, O.Ambacher
Wettability investigations and wet transfer enhancement of large-area CVD-graphene on aluminum nitride
2017 J Nanomater, Band: 7, Nummer: 8, Seite: 226
Richter Armin, Benick Jan, Feldmann Frank, Fell Andreas, Hermle Martin, Glunz Stefan
n-Type Si solar cells with passivating electron contact: Identifying sources for efficiency limitations by wafer thickness and resistivity variation
2017 Solar Energy Materials and Solar Cells
Richter Armin, Benick Jan, Feldmann Frank, Fell Andreas, Hermle Martin, Glunz Stefan
n-Type Si solar cells with passivating electron contact: Identifying sources for efficiency limitations by wafer thickness and resistivity variation.
2017 Solar Energy Materials and Solar Cells, Band: 173, Seite: 96–105
KurzfassungIn this work, the efficiency of n-type silicon solar cells with a front side boron-doped emitter and a full-area tunnel oxide passivating electron contact was studied experimentally as a function of wafer thickness W and resistivity ρb. Conversion efficiencies in the range of 25.0% have been obtained for all variations studied in this work, which cover 150 µm to 400 µm thick wafers and resistivities from 1 Ω cm to 10 Ω cm. We present a detailed cell analysis based on three-dimensional full-area device simulations using the solar cell simulation tool Quokka. We show that the experimental variation of the wafer thickness and resistivity at device level in combination with a detailed simulation study allows the identification of recombination induced loss mechanisms. This is possible because different recombination mechanisms can have a very specific influence on the I-V parameters as a function of W and ρb. In fact, we identified Shockley-Read-Hall recombination in the c-Si bulk as the source of a significant FF reduction in case of high resistivity Si. This shows that cells made of high resistivity Si are very sensitive to even a weak lifetime limitation in the c-Si bulk. Applying low resistivity 1 Ω cm n-type Si in combination with optimized fabrication processes, we achieved confirmed efficiency values of 25.7%, with a VOC of 725 mV, a FF of 83.3% and a JSC of 42.5 mA/cm2. This represents the highest efficiency reported for both-sides contacted c-Si solar cells. Thus, the results presented in this work demonstrate not only the potential of the cell structure, but also that a variation of the wafer thickness and resistivity at device level can provide deep insights into the cell performance.

2016

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D.Bleh, M.Roesch, M.Kuri, A.Dyck, A.Tessmann, A.Leuther, S.Wagner, O.Ambacher
A 100 GHz FMCW MIMO radar system for 3D image reconstruction
2016 European Radar Conference (EuRAD), Seiten: 37 - 40
B.Amado-Rey, Y.Campos-Roca, C.Friesicke, A.Tessmann, R.Lozar, S.Wagner, A.Leuther, M.Schlechtweg, O.Ambacher
A 280 GHz stacked-FET power amplifier cell using 50 nm metamorphic HEMT technology
2016 11th European Microwave Integrated Circuits Conference (EuMIC), Seiten: 189 - 192
C.Friesicke, P.Feuerschuetz, R.Quay, O.Ambacher, A.F.Jacob
A 40 dBm AlGaN/GaN HEMT power amplifier MMIC for SatCom applications at K-band
2016 IEEE MTT-S International Microwave Symposium (IMS), San Francisco, CA, Seiten: 1 - 4
F.Maier, D.Krausse, D.Gruner, R.Reiner, P.Waltereit, R.Quay, O.Ambacher
A GaN-Based 10.1 MHz Class-F-1 300 W Continuous Wave Amplifier Targeting Industrial Power Applications
2016 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
F.Thome, O.Ambacher
A W-band wireless communication transmitter utilizing a stacked-FET oscillator for high output power performance
2016 IEEE MTT-S International Microwave Symposium (IMS), San Francisco, CA, Seiten: 1 - 4
B.Amado-Rey, Y.Campos-Roca, C.Friesicke, A.Tessmann, H.Massler, S.Wagner, A.Leuther, M.Schlechtweg, O.Ambacher
A broadband 175–245 GHz balanced medium power amplifier using 50-nm mHEMT technology
2016 Microwave Conference (APMC), Asia-Pacific, Seiten: 1 - 4
A.Tessmann, A.Leuther, H.Massler, S.Wagner, F.Thome, M.Schlechtweg, O.Ambacher
A millimeter-wave low-noise amplifier MMIC with integrated power detector and gain control functionality
2016 IEEE MTT-S International Microwave Symposium (IMS), Nummer: 3, Seiten: 1 - 3
Isakov, M., May, M., Hiermaier, S., Kuokkala, V.-T.
A model for the strain rate dependent plasticity of a metastable austenitic stainless steel
2016 Materials and design, Band: 106, Seiten: 258 - 272
KurzfassungA continuum material model is developed for the dynamic plastic deformation behavior of metastable austenitic stainless steel EN 1.4318-2B. An incremental approach in both experimental testing and in the model is used to distinguish between the direct effects of strain rate and the macroscopic adiabatic heating effects. In the model a set of evolution equations is integrated over the deformation path, which makes the model flexible in terms of changes in the strain rate and material temperature. The strain-induced phase transformation from austenite to a'-martensite is accounted for with evolution equations based on the Olson-Cohen transformation model. In order to describe the phase transformation accurately during dynamic loading, the original model is modified by adding instantaneous strain rate sensitivity to the a'-transformation rate. Comparison with experimental results shows that the model can be used to describe the strain rate and temperature dependent behavior of a metastable austenitic alloy with a reasonable number of material parameters. Finally, the model gives realistic results in a set of validation experiments.
Andricevic N, Duddeck F, Hiermaier S
A novel approach for the assessment of robustness of vehicle structures under crash
2016 International journal of crashworthiness, Band: 21, Nummer: 2, Seiten: 89 - 103
KurzfassungThe use of numerical optimisation in vehicle development aiming at designing increasingly lighter vehicle structures may lead to a highly sensitive behaviour in terms of crashworthiness. Methods for the analysis of robustness have been introduced to account for the impact of varying input parameters, possibly detecting undesired deformation modes due to bifurcations. The objective of this paper is to introduce an index for the quantitative assessment of robustness of vehicle structures under crash. The novel approach is applied to axially impacted extrusion profiles as well as to an assembly of extrusion profiles under varying input parameters. It was found that the new Robustness Index accurately reflects the findings from state-of-the-art methods of robustness analysis, enabling an objective and transparent overall assessment of robustness prior to a potential in-depth analysis.
Andricevic, N., Duddeck, F., Hiermaier, S.
A novel approach for the assessment of robustness of vehicle structures under crash
2016 International journal of crashworthiness, Band: 21, Seite: 15
KurzfassungThe use of numerical optimisation in vehicle development aiming at designing increasingly lighter vehicle structures may lead to a highly sensitive behaviour in terms of crashworthiness. Methods for the analysis of robustness have been introduced to account for the impact of varying input parameters, possibly detecting undesired deformation modes due to bifurcations. The objective of this paper is to introduce an index for the quantitative assessment of robustness of vehicle structures under crash. The novel approach is applied to axially impacted extrusion profiles as well as to an assembly of extrusion profiles under varying input parameters. It was found that the new Robustness Index accurately reflects the findings from state-of-the-art methods of robustness analysis, enabling an objective and transparent overall assessment of robustness prior to a potential in-depth analysis.
K.Hahmann, B.Klenner, M.Ulrich, O.Ambacher
A portable W-band radar system for enhancement of infrared vision in fire fighting operations
2016 SPIE digital library
M. Schlechtweg, A. Tessmann, A. Leuther, H. Massler, G. Moschetti, O. Ambacher
Advanced building blocks for (Sub-) millimeter-wave applications in space, communication, and sensing using III/V mHEMT technology
2016 Global Symposium on Millimeter Waves (GSMM) & ESA Workshop on Millimetre-Wave Technology and Applications, Espoo, Seiten: 1 - 4
F.Thome, M.Ohlrogge, A.Leuther, M.Schlechtweg, O.Ambacher
An investigation of millimeter wave switches based on shunt transistors including SPDT SWITCH MMICs up to 300 GHz
2016 IEEE MTT-S International Microwave Symposium (IMS), San Francisco, CA, Seiten: 1 - 4
B.Weiss, R.Reiner, P.Waltereit, R.Quay, O.Ambacher
Analysis and modeling of GaN-based multi field plate Schottky power diodes
2016 IEEE 17th Workshop on Control and Modeling for Power Electronics (COMPEL), Seiten: 1 - 6
M.Reusch, K.Holc, W.Pletschen, L.Kirste, A. Zukauskaité, T.Yoshikawa, D.Iankow, O.Ambacher, V.Lebedev
Analysis and optimization of sputter deposited AlN-layers for flexural plate wave devices
2016 J Vac Sci Technol B, Band: 34, Nummer: 5, Ergänzungsband: 052001, Seiten: 1 - 10
Diehl Patrick, Franzelin Fabian, Pflüger Dirk, Ganzenmüller Georg
Bond-based peridynamics
2016 International Journal of Fracture, Band: 201, Nummer: 2, Seiten: 157 - 170
KurzfassungThis paper shows a new approach to estimate the critical traction for Mode I crack opening before crack growth by numerical simulation. For quasi-static loading, Linear Elastic Fracture Mechanics predicts the critical traction before crack growth. To simulate the crack growth, we used bond-based peridynamics, a non-local generalization of continuum mechanics. We discretize the peridynamics equation of motion with a collocation by space approach, the so-called EMU nodal discretization. As the constitutive law, we employ the improved prototype micro brittle material model. This bond-based material model is verified by the Young’s modulus from classical theory for a homogeneous deformation for different quadrature rules. For the EMU-ND we studied the behavior for different ratios of the horizon and nodal spacing to gain a robust value for a large variety of materials. To access this wide range of materials, we applied sparse grids, a technique to build high-dimensional surrogate models. Sparse grids significantly reduce the number of simulation runs compared to a full grid approach and keep up a similar approximation accuracy. For the validation of the quasi-static loading process, we show that the critical traction is independent of the material density for most material parameters. The bond-based IPMB model with EMU nodal discretization seems very robust for the ratio $$\delta /\varDelta X=3$$ δ / Δ X = 3 for a wide range of materials, if an error of 5Â % is acceptable.
D.Schwantuschke, B.Godejohann, S.Breuer, P.Bruckner, M.Mikulla, R.Quay, O.Ambacher
Broadband E-band power amplifier MMIC based on an AlGaN/GaN HEMT technology with 30 dBm output power
2016 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS)
Steinkemper Heiko, Michl Bernhard, Hermle Martin, Glunz Stefan
Choosing the best silicon material parameters for different solar cell architectures
2016 Energy Procedia, Band: 92, Seiten: 225 - 231
M.Roesch, A.Tessmann, A.Leuther, M.Kuri, S.Wagner, O.Ambacher, H.Hulan
Compact W-band receiver module on hybrid liquid crystal polymer board
2016 46th European Microwave Conference (EuMC), Seiten: 1517 - 1520
M.Ohlrogge, A.Tessmann, A.Leuther, M.Schlechtweg, O.Ambacher
Complex interaction of passive multiport structures and their description by separate discrete models
2016 Electron Lett, Band: 52, Nummer: 1, Seiten: 52 - 54
Steinkemper Heiko, Hermle Martin, Glunz Stefan
Comprehensive simulation study of industrially relevant silicon solar cell architectures for an optimal material parameter choice
2016 Prog Photovoltaics, Band: 24, Nummer: 10, Seiten: 1319 - 1331
Niewelt Tim, Schön Jonas, Warta Wilhelm, Glunz Stefan, Schubert Martin
Degradation of crystalline silicon due to boron–oxygen defects
2016 IEEE Journal of Photovoltaics, Band: 7, Nummer: 1, Seiten: 383 - 398
Niewelt Tim, Schön Jonas, Warta Wilhelm, Glunz Stefan, Schubert Martin
Degradation of crystalline silicon due to boron–oxygen defects
2016 IEEE Journal of Photovoltaics, Band: 7, Nummer: 1, Seite: 383–398
KurzfassungThis paper gives an overview on the current understanding of a technologically relevant defect group in crystalline silicon related to the presence of boron and oxygen. It is commonly addressed as boron–oxygen defects and has been found to affect silicon devices, whose performance depends on minority charge carrier diffusion lengths—such as solar cells. The defects are a common limitation in Czochralski-grown p-type silicon, and their recombination activity develops under charge carrier injection and is, thus, commonly referred to as light-induced degradation. A multitude of studies investigating the effect have been published and introduced various trends and interpretations. This review intends to summarize established trends and provide a consistent nomenclature for the defect transitions in order to simplify discussion.
F.van Raay, R.Quay, D.Schwantuschke, M.Ohlrogge, D.Peschel, M.Schlechtweg, O.Ambacher
Dual-gate HEMT parameter extraction based on 2.5 D multiport simulation of passive structures
2016 11th European Microwave Integrated Circuits Conference (EuMIC), Seiten: 241 - 244
Cadoni E, Couque H, Hiermaier S
Editorial
2016 European physical journal special topics, Band: 225, Nummer: 2
Cadoni, E., Couque, H., Hiermaier, S.
Editorial
2016 European physical journal special topics, Band: 225, Seite: 229
T.Yoshikawa, M.Reusch, V.Zuerbig, V.Cimalla, K.-H.Lee, M.Kurzyp, J.-C.Arnault, C.Nebel, O.Ambacher, V.Lebedev
Electrostatic self-assembly of diamond nanoparticles onto Al- and N-Polar sputtered aluminum nitride surfaces
2016 Nanomaterials-basel, Band: 6, Seiten: 11 - 20
T.Yoshikawa, M.Reusch, K.Holc, D.Iankov, V.Zuerbig, A.Zukauskaite, Nebel Christoph E, Ambacher Oliver, Lebedev Vadim
Enhanced actuation of nanocrystalline diamond microelectromechanical disk resonators with AlN layers
2016 Appl Phys Lett, Band: 108, Nummer: 17, Seite: 171903
E.Ture, P.Brueckner, R.Quay, O.Ambacher, M.Alsharef, R.Granzner, F.Schwierz
Enhancement-mode AlGaN/GaN FinFETs with high on/off performance in 100 nm gate length
2016 11th European Microwave Integrated Circuits Conference (EuMIC), Seiten: 61 - 64
Dlugosch M, Lukaszewicz D, Fritsch J, Hiermaier S
Experimental investigation of hybrid material systems consisting of advanced composites and sheet metal
2016 Composite structures, Band: 152, Seiten: 840 - 849
KurzfassungPrevious studies have identified composite-metal hybrid material systems in automotive crash structural applications as a possible solution to meet the demands of both ambitious efficiency goals and increasingly strict vehicle safety requirements. The purpose of this study is to experimentally identify basic principles, which define the material systemsâ properties such as the stiffness and strength as well as major parameter effects on a coupon scale. A further aim is to compare these findings to common approaches such as the rule-of-mixture theory and define analytical models able to predict these properties based on a set of parameter values. While there is a strong dominance of the steel phase, the experiments generally confirm the rule-of-mixture theory. Some effects might have to be considered when designing hybrid material systems for technical applications, such as the shift of the special neutral plane in asymmetric layups or a changed failure mode for different loading directions. The analytical models presented do match the experimental results, although the complex interaction between the material phases is not fully analyzed.
Dlugosch, M., Lukaszewicz, D., Fritsch, J., Hiermaier, S.
Experimental investigation of hybrid material systems consisting of advanced composites and sheet metal
2016 Composite structures, Band: 152, Seiten: 840 - 849
KurzfassungPrevious studies have identified composite-metal hybrid material systems in automotive crash structural applications as a possible solution to meet the demands of both ambitious efficiency goals and increasingly strict vehicle safety requirements. The purpose of this study is to experimentally identify basic principles, which define the material systems' properties such as the stiffness and strength as well as major parameter effects on a coupon scale. A further aim is to compare these findings to common approaches such as the rule-of-mixture theory and define analytical models able to predict these properties based on a set of parameter values. While there is a strong dominance of the steel phase, the experiments generally confirm the rule-of-mixture theory. Some effects might have to be considered when designing hybrid material systems for technical applications, such as the shift of the special neutral plane in asymmetric layups or a changed failure mode for different loading directions. The analytical models presented do match the experimental results, although the complex interaction between the material phases is not fully analyzed.
D.Schwantuschke, R.Henneberger, S.Wagner, A.Tessmann, I.Kallfass, P.Brueckner, R.Quay, O.Ambacher
Gan-based e-band power amplifier modules
2016 46th European Microwave Conference (EuMC)
A.Zibold, R.Reiner, B.Weiss, M.Kunzer, R.Quay, J.Wagner, P.Waltereit, O.Ambacher
High voltage GaN-based Schottky diodes in non-isolated LED buck converters
2016 18th European Conference on Power Electronics and Applications (EPE'16 ECCE Europe), Seiten: 1 - 9
E.Ture, B.Brueckner, B.Godejohann, R.Aidam, M.Alsharef, R.Granzner, F.Schwierz, R.Quay, O.Ambacher
High-current submicrometer tri-gate GaN high-electron mobility transistors with binary and quaternary barriers
2016 IEEE Xplore Digital Library, Band: 4, Nummer: 1, Seiten: 1 - 6
E.Ture, P.Brueckner, B.-J.Godejohann, R.Aidam, M.Alsharef, R.Granzner, F.Schwierz, R.Quay, O.Ambacher
High-current submicrometer tri-gate GaN high-electron mobility transistors with binary and quaternary barriers
2016 Journal of the Electron Devices Society, Band: 4, Nummer: 1, Seiten: 1 - 6
Ganzenmüller G, Sauer M, May M, Hiermaier S
Hourglass control for Smooth Particle Hydrodynamics removes tensile and rank-deficiency instabilities
2016 EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS, Band: 225, Nummer: 2, Seiten: 385 - 395
KurzfassungWe present a stabilization scheme for elastoplastic Smooth-Particle Hydrodynamics (SPH) which overcomes two major challenges: (i) the tensile instability inherent to the updated Lagrangian approach is suppressed and (ii) the rank-deficiency instability inherent to the nodal integration approach is cured. To achieve these goals, lessons learned from the Finite-Element Method are transferred to SPH. In particular, an analogue of hourglass control is derived for SPH, which locally linearizes the deformation field to obtain stable and accurate solutions, without the need to resort to stabilization via excessive artificial viscosity. The resulting SPH scheme combines the ability of updated Lagrangian SPH to model truly large deformations with the accuracy and stability needed to faithfully perform simulations. This claim is supported by the analysis of problematic cases and the simulation of an impact scenario.
Ganzenmüller G, Sauer M, May M, Hiermaier S
Hourglass control for Smooth Particle Hydrodynamics removes tensile and rank-deficiency instabilities
2016 European physical journal special topics, Band: 225, Nummer: 2, Seiten: 385 - 395
KurzfassungWe present a stabilization scheme for elastoplastic Smooth-Particle Hydrodynamics (SPH) which overcomes two major challenges: (i) the tensile instability inherent to the updated Lagrangian approach is suppressed and (ii) the rank-deficiency instability inherent to the nodal integration approach is cured. To achieve these goals, lessons learned from the Finite-Element Method are transferred to SPH. In particular, an analogue of hourglass control is derived for SPH, which locally linearizes the deformation field to obtain stable and accurate solutions, without the need to resort to stabilization via excessive artificial viscosity. The resulting SPH scheme combines the ability of updated Lagrangian SPH to model truly large deformations with the accuracy and stability needed to faithfully perform simulations. This claim is supported by the analysis of problematic cases and the simulation of an impact scenario.
Ganzenmueller, G., Sauer, M., May, M., Hiermaier, S.
Hourglass control for Smooth Particle Hydrodynamics removes tensile and rank-deficiency instabilities : Hourglass control for SPH
2016 European physical journal special topics, Band: 225, Seiten: 385 - 395
KurzfassungWe present a stabilization scheme for elastoplastic Smooth-Particle Hydrodynamics (SPH) which overcomes two major challenges: (i) the tensile instability inherent to the updated Lagrangian approach is suppressed and (ii) the rank-deficiency instability inherent to the nodal integration approach is cured. To achieve these goals, lessons learned from the Finite-Element Method are transferred to SPH. In particular, an analogue of hourglass control is derived for SPH, which locally linearizes the deformation field to obtain stable and accurate solutions, without the need to resort to stabilization via excessive artificial viscosity. The resulting SPH scheme combines the ability of updated Lagrangian SPH to model truly large deformations with the accuracy and stability needed to faithfully perform simulations. This claim is supported by the analysis of problematic cases and the simulation of an impact scenario.
Eberle Rebekka, Kwapil Wolfram, Schindler Florian, Schubert Martin, Glunz Stefan
Impact of the firing temperature profile on light induced degradation of multicrystalline silicon
2016 physica status solidi (RRL) - Rapid Research Letters, Band: 10, Nummer: 12, Seite: 861–865
KurzfassungLight- and elevated temperature-induced degradation in multicrystalline silicon can reduce the efficiency of solar cells significantly. In this work, the influence of the firing process and its temperature profile on the degradation behaviour of neighbouring mc-Si wafers is analysed. Five profiles with measured high peak temperatures ≥800 °C and varying heating and cooling ramps are examined. With spatially resolved and lifetime calibrated photoluminescence images, normalized defect concentrations N*t are calculated to determine the degradation intensity. Wafers that underwent a fast firing process typical for industrial solar cell production show a significantly stronger degradation than samples that were subjected to the same peak temperature but with slower heating and cooling rates. A spatially resolved analysis of the carrier lifetime in the whole wafer shows that the degradation begins in low lifetime areas around dislocation clusters, spreading into good grains after several hours. By the use of optimized ramp-up and/or ramp-down rates during the firing even at very high peak temperatures, light and elevated temperature induced degradation can be suppressed. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)
Klomfass A, Stolz A, Hiermaier S
Improved explosion consequence analysis with combined CFD and damage models
2016 , Seiten: 109 - 114
KurzfassungThe most-widely used approach to explosion consequence analysis is the classical engineering method based on the combination of TNT equivalence, scaled distances and overpressure-based damage levels. This approach rests on established and easily comprehensible elements and permits a fast assessment of explosion consequences. There are however several limitations inherent in this approach. In contrast, a simulation-based approach using computational fluid dynamics (CFD) and structural dynamics (CSD) methods permits an analysis with a high level of detail regarding both the prediction of the explosive loads and the caused damage. This comes at the cost of complex simulation models which require expert knowledge, intense validation and a high computational effort. To bridge the gap between the classical simplified approach and the CFD/CSD based methods, we have developed a specialized CFD tool, the APOLLO Blastsimulator, with a built-in library of experimentally validated damage models and blast-injury models suitable for an improved explosion consequence analysis. The high resolution CFD tool uses globally and locally adaptive Cartesian grids and includes models for TNT detonations as well as gas detonations. The built-in damage models are based on experimentally validated single-degree-of-freedom (SDOF) representations of structural components. This paper gives a brief review on the classical approaches and their limitations and an overview on the concepts used in the APOLLO Blastsimulator and the SDOF damage models. For an exemplary explosion scenario the results obtained with different explosive source and damage models are compared.
Hess, S, Beukes, H, Smith, G, Dinter, F
Initial Study on Solar Process Heat for South African Sugar Mills
2016 Int Sugar J, Seiten: 236 - 248
Hess, S, Beukes, H, Smith, G, Dinter, F
Initial Study on Solar Process Heat for South African Sugar Mills
2016 Proceedings of the South African Sugar Technologists’ Association, Seiten: 324 - 349

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M.Himmerlich, A.Eisenhardt, T.Berthold, Ch.Y.Wang, V.Chimalla, O.Ambacher, S.Krischok
Interaction of indium oxide nanoparticle film surfaces with ozone, oxygen and water
2016 Phys Status Solidi A, Band: 213, Nummer: 3, Seiten: 831 - 838
V.Carrubba, S.Maroldt, E.Ture, U.Udeh, M.Musser, W.Bronner, R.Quay, O.Ambacher
Internally-packaged-matched continuous inverse class-FI wideband GaN HPA
2016 11th European Microwave Integrated Circuits Conference (EuMIC), Seiten: 233 - 236
Joubert, E, Hess, S, van Niekerk, JL
Large-Scale Solar Water Heating in South Africa: Status, Barriers and Recommendations
2016 Renew Energ, Nummer: 97, Seiten: 809 - 822
R.Reiner, P.Waltereit, B.Weiss, M.Wespel, D.Meder, M.Mikulla, R.Quay, O.Ambacher
Linear temperature sensors in high-voltage GaN-HEMT power devices
2016 Applied Power Electronics Conference and Exposition (APEC), Seiten: 2083 - 2086
M.Roesch, A.Tessmann, A.Leuther, R.Weber, G.Moschetti, B.Aja, M.Kotiranta, H.Massler, V.Kangas, M.Perichaud, M.Schlechtweg, O.Ambacher
Low noise amplifiers for MetOp-SG
2016 Global Symposium on Millimeter Waves (GSMM) & ESA Workshop on Millimetre-Wave Technology and Applications, Seiten: 1 - 4
M.Klenner, C.Zech, A.Huelsmann, J.Kuehn, M.Schlechtweg, O.Ambacher
Material characterization using a compact W-band ellipsometer
2016 46th European Microwave Conference (EuMC), Seiten: 803 - 806
C.Zech, B.Baumann, A.Huelsmann, J.Kuehn, M.Schlechtweg, O.Ambacher
Measurement setup for the analysis of broadband frequency-modulated signals
2016 46th European Microwave Conference (EuMC), Seiten: 389 - 392
B. Hannemann, S. Backe, S. Schmeer, F. Balle, U.P. Breuer
Metal fiber incorporation in carbon fiber reinforced polymers (CFRP) for improved electrical conductivity
2016 Materialwiss Werkst, Band: 47, Nummer: 11, Seiten: 1015 - 1023
R.Reiner, P.Waltereit, B.Weiss, M.Wespel, M.Mikulla, R.Quay, O.Ambacher
Monolithic gan-on-si half-bridge circuit with integrated freewheeling diodes
2016 PCIM Europe; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Seiten: 1 - 7
Bolivar Jaramillo L, Weidlich A
Optimal microgrid scheduling with peak load reduction involving an electrolyzer and flexible loads
2016 Applied Energy, Band: 169, Seiten: 857 - 865

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C.Friesicke, T.Maier, P.Brueckner, R.Quay, O.Ambacher
Packaged AlGaN/GaN HEMT power bars with 900 W output power and high PAE at L-band
2016 46th European Microwave Conference (EuMC), Seiten: 409 - 412
M.Alsharef, R.Granzner, F.Schwierz, E.Ture, R.Quay, O.Ambacher
Performance of tri-gate AlGaN/GaN HEMTs
2016 46th European Solid-State Device Research Conference (ESSDERC), Seiten: 176 - 179
B.Christian, J.Volk, I.Lukács, C.Sturm, A.Graillot, R.Dauksevicius, E. O’Reilly, O.Ambacher, V.Lebedev
Piezo-force and vibration analysis of ZnO nanowire arrays for sensor application
2016 Procedia Engineering, Band: 168, Seiten: 1192 - 1195
M.Reusch, K.Holc, L.Kirste, P.Katus, L.Reindl, O.Ambacher, V.Lebedev
Piezoelectric AlN Films for FPW Sensors with Improved Device Performance
2016 Procedia Engineering, Band: 168, Seiten: 1040 - 1043
T.Yoshikawa, F.Gao, V.Zuerbig, C.Giese, C.Nebel, O.Ambacher
Pinhole-free ultra-thin nanocrystalline diamond film growth via electrostatic self-assembly seeding with increased salt concentration of nanodiamond colloids
2016 Diamond and Related Materials, Band: 63, Seiten: 103 - 107
S.Jauss, S.Schwaiger, W.Daves, O.Ambacher
Poly-silicon CMOS compatible gate module for AlGaN/GaN-on-silicon MIS-HEMTs for power electronics applications
2016 28th International Power Semiconductor Devices and ICs (ISPSD), Seiten: 83 - 86
S.A.Jauss, S.Kilian, S.Schwaiger, S.Noll, W.Daves, O.Ambacher
Post drain-stress behavior of AlGaN/GaN-on-Si MIS-HEMTs
2016 Solid State Electronics, Band: 125, Seiten: 125 - 132
F.Thome, S.Maroldt, O.Ambacher
Prospects and limitations of stacked-FET approaches for enhanced output power in voltage-controlled oscillators
2016 Ieee T Microw Theory, Band: 64, Nummer: 3, Seiten: 836 - 846
A.Mueller, M.C.Wapler, U.T.Schwarz, M.Reisacher, K.Holc, O.Ambacher, U.Wallrabe
Quasi-Bessel beams from asymmetric and astigmatic illumination sources
2016 Opt Express, Band: 24, Nummer: 15, Seiten: 17433 - 17452
M.Alsharef, M.Christiansen, R.Granzner, E.Ture, R.Quay, O.Ambacher, F.Schwierz
RF performance of trigate GaN HEMTs
2016 Ieee T Electron Dev, Band: 63, Nummer: 11, Seiten: 4255 - 4261
S.Moench, I.Kallfass, R.Reiner, B.Weiss, P.Waltereit, R.Quay, O.Ambacher
Single-input GaN gate driver based on depletion-mode logic integrated with a 600 v gan-on-si power transistor
2016 IEEE 4th Workshop on Wide Bandgap Power Devices and Applications (WiPDA), Seiten: 204 - 209
A.Endruschat, T.Heckel, R.Reiner, P.Waltereit, R.Quay, O.Ambacher, M.März, B.Eckardt, L.Frey
Slew rate control of a 600 V 55 mΩ GaN cascade
2016 IEEE 4th Workshop on Wide Bandgap Power Devices and Applications (WIPDA), Seiten: 334 - 339
KurzfassungThis paper presents a 600 V, 55 m Omega GaN cascode with slew rate control. The time constants of cascodes which determine the switching speed are analyzed, discussed and verified by time domain simulations. Clamped inductive switching measurements of commercial and a custom-built GaN cascodes prove the applicability of the switching speed control mechanisms with additional passive components. The gathered experiences are applied to a custom-built modular cascode, which shows simple switching speed controllability by utilizing a standard gate drive.
M.Ohlrogge, A.Tessmann, A.Leuther, R.Weber, H.Massler, O.Ambacher
Small signal modelling approach for submillimeter wave III–V HEMTs with analysation and optimization possibilities
2016 IEEE MTT-S International Microwave Symposium (IMS), San Francisco, CA, Seiten: 1 - 4
Leroch S, Varga M, Eder S, Vernes A, Ripoll M, Ganzenmueller G
Smooth particle hydrodynamics simulation of damage induced by a spherical indenter scratching a viscoplastic material
2016 THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, PERGAMON-ELSEVIER SCIENCE LTD, Band: 81, Seiten: 188 - 202
KurzfassungWe present an implementation of a (mesh-free) smooth particle hydrodynamics (SPH) algorithm, intended for the application to solid bodies, and use it to simulate scratch-induced surface damage on an elasto-viscoplastic material. If conventional SPH is used to simulate solids, an unphysically high artificial viscosity is required to damp strong oscillatory modes and thus stabilize the system. To overcome these intrinsic difficulties associated with modeling solid bodies, the recently implemented so-called total-Lagrangian SPH utilizes an hourglass control scheme similar to what is known from finite element algorithms. Elasto-viscoplastic material properties are modeled by using the Mie-Gruneisen equation of state and the Johnson-Cook model. The material parameters are selected to reproduce the strain-stress behavior of annealed oxygen-free high conductivity copper. The spherical indenter is modeled as a rigid sphere. The topographies of the calculated scratch-induced surface damage are in excellent agreement with experimental scratch tests carried out at comparable normal loads. We also calculate the real contact area between the indenter and the surface, allowing a sound estimation of the scratch hardness. (C) 2015 Elsevier Ltd. All rights reserved.
B.Weiss, R.Reiner, P.Waltereit, R.Quay, O.Ambacher, A.Sepahvand, D. Maksimovic
Soft-switching 3 MHz converter based on monolithically integrated half-bridge GaN-chip
2016 IEEE 4th Workshop on Wide Bandgap Power Devices and Applications (WiPDA), Seiten: 215 - 219
M.Klenner, C.Zech, A.Huelsmann, J.Kuehn, M.Schlechtweg, O.Ambacher
Spectroscopic measurement of material properties using an improved millimeter-wave ellipsometer based on metallic substrates
2016 Ieee T Instrum Meas, Band: 65, Nummer: 11, Seiten: 2251 - 2559
G.Moschetti, F.Thome, M.Ohlrogge, J.Goliasch, F.Schaefer, G.Aja, A.Leuther, M.Schlechtweg, M.G.Wiesching, M.Kotiranta Seelmann-Eggebert, O.Ambacher
Stability investigation of large gate-width metamorphic high electron-mobility transistors at cryogenic temperature
2016 Ieee T Thz Sci Techn, Band: 64, Seiten: 10 - 22
J.Stehle, O.Ambacher, A.Samarao, G.Yama, U.Krishnamoorthy
Study of a silicon parallel plate capacitor as a dew point sensor
2016 Ieee Sens J, Seiten: 1 - 3
Fischer K, Häring I, Riedel W, Vogelbacher G, Hiermaier S
Susceptibility, vulnerability, and averaged risk analysis for resilience enhancement of urban areas
2016 International journal of protective structures, Band: 7, Nummer: 1, Seiten: 45 - 76
KurzfassungThe dynamic growth and evolution of urban areas generate new challenges for safety and security driving societal, economic, and ecological developments at local and worldwide levels. Cities comprise a high degree of critical infrastructure with an increasing complexity and interdependency. In addition, modified and new threats ranging from natural to man-made and malicious hazards ask for more robust and sustainable cities. This work combines and extends existing empirical, engineering, and simulative methods to define and determine quantities for resilience assessment of urban areas in a comprehensive approach. Based on a multitude of possible events in a city quarter with a larger number of infrastructures, susceptibilities, vulnerabilities, and averaged risks are analyzed in a systematic and quantitative way. The use of an established empirical-historical database gives first insights to identify susceptible elements or endangered areas in the considered urban environments. It is coupled to an approach for consequences where state-of-the-art physical-engineering hazard and damage propagation and quantification models are integrated for vulnerability assessment. The consideration of multiple threats and multiple possible locations cumulates in an object- and location-dependent quantification of averaged risks to visualize the most critical regions and infrastructure aspects in densely populated areas. In this article, the approach is exemplarily applied to terroristic threats. The integration of the three-dimensional visualized approach into existing risk assessment and management processes will help to create cities that are more resilient.
Fischer, Kai, Haering, Ivo, Riedel, Werner, Vogelbacher, Georg, Hiermaier, Stefan
Susceptibility, vulnerability, and averaged risk analysis for resilience enhancement of urban areas
2016 International journal of protective structures, Band: 7, Seiten: 45 - 76
KurzfassungThe dynamic growth and evolution of urban areas generate new challenges for safety and security driving societal, economic, and ecological developments at local and worldwide levels. Cities comprise a high degree of critical infrastructure with an increasing complexity and interdependency. In addition, modified and new threats ranging from natural to man-made and malicious hazards ask for more robust and sustainable cities. This work combines and extends existing empirical, engineering, and simulative methods to define and determine quantities for resilience assessment of urban areas in a comprehensive approach. Based on a multitude of possible events in a city quarter with a larger number of infrastructures, susceptibilities, vulnerabilities, and averaged risks are analyzed in a systematic and quantitative way. The use of an established empirical-historical database gives first insights to identify susceptible elements or endangered areas in the considered urban environments. It is coupled to an approach for consequences where state-of-the-art physical-engineering hazard and damage propagation and quantification models are integrated forvulnerability assessment. The consideration of multiple threats and multiple possible locations cumulates in an object- and location-dependent quantification of averaged risks to visualize the most critical regions and infrastructure aspects indensely populated areas. In this article, the approach is exemplarily applied to terroristic threats. The integration of the three-dimensional visualized approach into existing risk assessment and management processes will help to create cities that are more resilient.
Steinhauser Bernd, Jäger Ulrich, Benick Jan, Chong Ellen, Lam Jenny, Steeman Rob, Rostan Hannes, Nekarda Jan, Hermle Martin, Preu Ralf, Glunz Stefan
The influence of nitrogen on laser doping from phosphorous doped a-SiNx layers
2016 Solar Energy Materials and Solar Cells, Band: 157, Seiten: 295 - 304
J.Rombach, A.Papadogianni, M.Mischo, V.Cimalla, L.Kirste, O.Ambacher, T.Bechthold, S.Krischok, M.Himmerlich, S.Selve, S.O.Bierwagen
The role of surface electron accumulation and bulk doping for gas-sensing explored with single-crystalline In(2)O(3) thin films
2016 Sensor Actuat B-chem, Band: 236, Seiten: 909 - 916
Rauer M, Schmiga C, Raugewitz A, Glatthaar M, Glunz S
Theoretical and experimental investigation of aluminum-boron codoping of silicon
2016 Prog Photovoltaics, Band: 24, Nummer: 2, Seiten: 219 - 228
D. Backe, F. Balle, D. Eifler
Three Point Bending Fatigue of Carbon Fiber Fabric Reinforced Polyphenylensulfide in the Very High Cycle Fatigue Regime
2016 Key Engineering Materials, Band: 664, Seiten: 47 - 54
May Michael, Furlan Stefan, Mohrmann Holger, Ganzenmueller Georg
To replace or not to replace?
2016 ENGINEERING FAILURE ANALYSIS, Band: 60, Seiten: 9 - 19
KurzfassungThis paper presents a study on the residual strength of carabiners which have sustained impact damage due to accidental dropping during lead climbing. The question answered here is whether damaged quickdraws can be reused for future climbing or whether they should be replaced. Well defined damages were introduced into the main body and the gate of three different types of quickdraw carabiners. The carabiners were visually inspected and tested for functionality before the residual strength was measured following procedures defined in mountaineering standards. Contrary to common perception no micro-cracks were found within the damaged carabiners. In general, the carabiners tested here showed good resistance to impact damage. Impact on the main body does not seem to affect the residual strength. Impact on the wire gate may result in failure of the gate. However, if the gate is still functional, the strength is not affected by an impact. (C) 2015 Elsevier Ltd. All rights reserved.
M.Wespel, V.M.Polyakov, M.Dammann, R.Reiner, P.Waltereit, R.Quay, M.Mikulla, O.Ambacher
Trapping effects at the drain edge in 600 V GaN-on-Si HEMTs
2016 IEEE T Electron Dev, Band: 63,2, Seiten: 598 - 605
Lee Sang-Won, Kim Seongtak, Bae Soohyun, Cho Kyungjin, Chung Taewon, Mundt Laura, Lee Seunghun, Park Sungeun, Park Hyomin, Schubert Martin, Glunz Stefan, Ko Yohan, Jun Yongseok, Kang Yoonmook, Lee Hae-Seok, Kim Donghwan
UV degradation and recovery of perovskite solar cells
2016 Scientific Reports, Band: 6
D. Backe, F. Balle
Ultrasonic fatigue and microstructural characterization of carbon fiber fabric reinforced polyphenylene sulfide in the very high cycle fatigue regime
2016 Compos Sci Technol, Band: 126, Seiten: 115 - 121

2015

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Moschetti Giuseppe, Leuther Arnulf, Maßler Herman, Aja Beatriz, Rösch Markus, Schlechtweg Michael, Ambacher Oliver, Kangas Ville, Geneviève-Perichaud Marie
A 183 GHz metamorphic HEMT low-noise amplifier with 3.5 dB noise figure
2015 IEEE, Band: 25, Nummer: 9, Seiten: 618 - 620
B.Amado-Rey, Y.Campos-Roca, S.Maroldt, A.Tessmann, H.Massle, A.Leuther, M.Schlechtweg, O.Ambacher
A 200 GHz driver amplifier in metamorphic HEMT technology
2015 2015 Asia-Pacific Microwave Conference (APMC), Band: 2, Seiten: 1 - 3
C Zech, A Hülsmann, M Schlechtweg, S Reinold, C Giers, B Kleiner, L. Georgi, R. Kahle, K. F. Becker, O. Ambacher
A compact W-band LFMCW radar module with high accuracy and integrated signal processing
2015 European Microwave Conference (EuMC), Seiten: 554 - 557
V. Carrubba, E. Ture, S. Maroldt, M. Mußer, F. Van Raay, R. Quay, O. Ambacher
A dual-band UMTS/LTE highly power-efficient class-ABJ Doherty GaN PA
2015 10th European Microwave Integrated Circuits Conference (EuMIC), Seiten: 313 - 316
LĂ¤ssig T, Nguyen L, May M, Riedel W, Heisserer U, Werff H, Hiermaier S
A non-linear orthotropic hydrocode model for ultra-high molecular weight polyethylene in impact simulations
2015 International Journal of Impact Engineering, Band: 75, Seiten: 110 - 122
KurzfassungThis paper presents detailed experimental characterization of quasi-static anisotropic directional strength properties as well as the shock behavior of ultra-high molecular weight polyethylene (UHMWPE) for the development of an advanced material model for this class of materials. Specifically, we consider DyneemaÂŽ HB26 â pressed from uni-directional (UD) tapes in a 0/90Â° stacking sequence. A material model based on a constitutive law with orthotropic, non-linear strength, shock response, composite failure and softening criteria is presented. A set of material parameters is derived for applications in hydrocodes (here: ANSYS AUTODYN). High- and hypervelocity impact tests with different impact velocities are used for preliminary validation and discussion of the predictive capabilities in view of future application.
Laessig, T., Nguyen, L., May, M., Riedel, W., Heisserer, U., Werff, H. van der, Hiermaier, S.
A non-linear orthotropic hydrocode model for ultra-high molecular weight polyethylene in impact simulations
2015 International Journal of Impact Engineering, Band: 75, Seiten: 110 - 122
KurzfassungThis paper presents detailed experimental characterization of quasi-static anisotropic directional strength properties as well as the shock behavior of ultra-high molecular weight polyethylene (UHMWPE) for the development of an advanced material model for this class of materials. Specifically, we consider Dyneema� HB26 - pressed from uni-directional (UD) tapes in a 0/90� stacking sequence. A material model based on a constitutive law with orthotropic, non-linear strength, shock response, composite failure and softening criteria is presented. A set of material parameters is derived for applications in hydrocodes (here: ANSYS AUTODYN). High- and hypervelocity impact tests with different impact velocities are used for preliminary validation and discussion of the predictive capabilities in view of future application.
F.A. Maier, A. Grede, D. Gruner, R. Quay, P. Waltereit, O. Ambacher
A novel broadband high-power Source-Pull/Load-Pull concept for the HF-to UHF-range
2015 European Microwave Conference (EuMC), Seiten: 1279 - 1282
K Köhler, W Pletschen, B Godejohann, S Müller, HP Menner, O Ambacher
Admittance–voltage profiling of AlxGa1−xN/GaN heterostructures: Frequency dependence of capacitance and conductance
2015 J Appl Phys, Band: 118, Nummer: 12
M. Reusch, P. Katus, K. Holc, W. Pletschen, L. Kirste, V. Zuerbig, D. Iankov, L. Reindl, O. Ambacher, V. Lebedev
Aluminium nitride membranes with embedded buried idt electrodes for novel flexural plate wave devices
2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), Seiten: 1291 - 1294
Ganzenmueller Georg
An hourglass control algorithm for Lagrangian Smooth Particle Hydrodynamics
2015 PO BOX 564, 1001 LAUSANNE, SWITZERLAND COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, ELSEVIER SCIENCE SA, Band: 286, Seiten: 87 - 106
KurzfassungThis paper presents a stabilization scheme which addresses the rank-deficiency problem in meshless collocation methods for solid mechanics. Specifically, Smooth-Particle Hydrodynamics (SPH) in the Total Lagrangian formalism is considered. This method is rank-deficient in the sense that the SPH approximation of the deformation gradient is not unique with respect to the positions of the integration points. The non-uniqueness can result in the formation of zero-energy modes. If undetected, these modes can grow and completely dominate the solution. Here, an algorithm is introduced, which effectively suppresses these modes in a fashion similar to hour-glass control mechanisms in Finite-Element methods. Simulations utilizing this control algorithm exhibit much improved stability, accuracy, and error convergence properties. In contrast to an alternative method which eliminates zero-energy modes, namely the use of additional integration points, the here presented algorithm is easy to implement and computationally very efficient. (C) 2014 Elsevier B.V. All rights reserved.
May Michael, Ganzenmueller Georg, Wolfrum Johannes, Heimbs Sebastian
Analysis of composite T-joint designs for enhanced resistance to hydrodynamic ram
2015 THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND COMPOSITE STRUCTURES, ELSEVIER SCI LTD, Band: 125, Seiten: 188 - 194
KurzfassungThis study is concerned with the feasibility of different T-joint designs for application in aircraft composite fuel tanks which may be subjected to hydrodynamic ram loading. In a first step, the response of a hybrid metallic/composite T-joint is compared against a state-of-the-art composite T-joint. In a second step, two different resin systems are compared using a third T-joint design one state-of-the-art aerospace resin and one novel, toughened system. Experimental work is done under both, quasi-static and under high-rate loading conditions. The hybrid metallic/composite T-joint showed superior post-failure behavior compared to the state-of-the-art composite T-joint. The use of the toughened resin system results in a significant increase of joint strength. The post-failure behavior is however not affected by the resin system. (C) 2015 Elsevier Ltd. All rights reserved.
LĂ¤ssig T, Bagusat F, May M, Hiermaier S
Analysis of the shock response of UHMWPE composites using the inverse planar plate impact test and the shock reverberation technique
2015 International Journal of Impact Engineering, Band: 86, Seiten: 240 - 248
KurzfassungUltra-high molecular-weight polyethylene (UHMWPE) composites are commonly used in ballistic protection systems. In order to understand the behavior under shock conditions, dynamic material properties were recently measured by inverse planar plate impact tests providing USâuP-data for particle velocities from 170âm/s up to 900âm/s. In this paper the previously known data range is extended at both ends. On the one hand, inverse flyer plate tests were performed at impact velocities less than 200âm/s in order to assess potential effects of porosity. On the other hand, the mechanical response under extremely high pressures was determined using the shock reverberation technique. //For low shock pressures no effect of porosity was identified. For high shock pressures, the available data range was extended by a factor of 3. For the whole range of velocities and pressures, the slope of the USâuP relationship indicates a slight concave curvature.
Laessig, T., Bagusat, F., May, M., Hiermaier, S.
Analysis of the shock response of UHMWPE composites using the inverse planar plate impact test and the shock reverberation technique
2015 International Journal of Impact Engineering, Band: 86, Seiten: 240 - 248
KurzfassungUltra-high molecular-weight polyethylene (UHMWPE) composites are commonly used in ballistic protection systems. In order to understand the behavior under shock conditions, dynamic material properties were recently measured by inverse planar plate impact tests providing US-uP-data for particle velocities from 170 m/s up to 900 m/s. In this paper the previously known data range is extended at both ends. On the one hand, inverse flyer plate tests were performed at impact velocities less than 200 m/s in order to assess potential effects of porosity. On the other hand, the mechanical response under extremely high pressures was determined using the shock reverberation technique. //For low shock pressures no effect of porosity was identified. For high shock pressures, the available data range was extended by a factor of 3. For the whole range of velocities and pressures, the slope of the US-uP relationship indicates a slight concave curvature.
T. Yoshikawa, V. Zürbig, F. Gao, R. Hoffmann, C. Nebel, O. Ambacher, V. Lebedev
Appropriate salt concentration of nanodiamond colloids for electrostatic self-assembly seeding of monosized individual diamond nanoparticles on silicon dioxide surfaces
2015 Langmuir, Band: 31, Nummer: 19, Seiten: 5319 - 5325
R. Granzner, V. M. Polyakov, V. Cimalla, O. Ambacher, F. Schwierz
Bias-free lateral terahertz emitters - a simulation study
2015 J Appl Phys, Band: 118, Nummer: 4
F. Van Raay, R. Quay, B. Aja, G. Moschetti, M. Seelmann-Eggebert, M. Schlechtweg, O. Ambacher
Broadband low-noise GaN HEMT TWAs using an active distributed drain bias circuit
2015 10th European Microwave Integrated Circuits Conference (EuMIC), Seiten: 156 - 159
M. Klenner, C. Zech, A. Hülsmann, M. Schlechtweg, O. Ambacher
Characterization of quasi-optical focusing systems at W-band frequencies
2015 European Microwave Conference (EuMC), Seiten: 311 - 314
H. Hahn, B. Reuters, S. Geipel, M. Schauerte, F. Benkhelifa, O. Ambacher, H. Kalisch, A. Vescan
Charge balancing in GaN-based 2-D electron gas devices employing an additional 2-D hole gas and its influence on dynamic behaviour of GaN-based heterostructure field effect transistors
2015 J Appl Phys, Band: 117, Nummer: 10
S.A. Jauss, S. Schwaiger, W. Daves, S. Noll, O. Ambacher
Charge trapping in gate-drain access region of AlGaN/GaN MIS-HEMTs after drain stress
2015 45th European Solid State Device Research Conference (ESSDERC), Seiten: 56 - 59
Helmke, A, Hess, S
Classification of Solar Process Heat System Concepts
2015 Integration Guideline - Guideline for Solar Planners, Energy Consultants and Process Engineers, Seiten: 61 - 76
F. Balle, D. Eifler, J.H. Fitschen, S. Schuff, G. Steidl
Computation and Visualization of Local Deformation for Multiphase Metallic Materials by Infimal Convolution of TV-Type Functionals
2015 International Conference on Scale Space and Variational Methods in Computer Vision, Seiten: 385 - 396
N. Espinosa, S. U. Schwarz, V. Cimalla, O. Ambacher
Detection of different target-DNA concentrations with highly sensitive AlGaN/GaN high electron mobility transistors
2015 Sensor Actuat B-chem, Band: 210, Seiten: 633 - 639
N. Espinosa, S. U. Schwarz, A. Podolska, O. Ambacher
Dynamic detection of target-DNA with AlGaN/GaN high electron mobility transistors
2015 Procedia Engineering, Band: 120, Seiten: 908 - 911
Isakov M, Hiermaier S, Kuokkala V.-T.
Effect of strain rate on the martensitic transformation during plastic deformation of an austenitic stainless steel
2015 Metallurgical and materials transactions. A, Band: 46, Nummer: 6, Seiten: 2352 - 2355
KurzfassungThe effect of strain rate on the plastic deformation and phase transformation behavior of metastable austenitic stainless steel EN 1.4318 was studied. Strain rate jump tests were used to distinguish the direct effects of strain rate from the effects of adiabatic heating. Test results are analyzed from the viewpoint of both stress- and strain-induced martensitic transformation.
Isakov, M., Hiermaier, S., Kuokkala, V.-T.
Effect of strain rate on the martensitic transformation during plastic deformation of an austenitic stainless steel
2015 Metallurgical and materials transactions. A, Band: 46, Seite: 4
KurzfassungThe effect of strain rate on the plastic deformation and phase transformation behavior of metastable austenitic stainless steel EN 1.4318 was studied. Strain rate jump tests were used to distinguish the direct effects of strain rate from the effects of adiabatic heating. Test results are analyzed from the viewpoint of both stress- and strain-induced martensitic transformation.
Kamp M, Maywald A, Bartsch J, Efinger R, Keding R, Glatthaar M, Glunz S, Krossing I
Electrochemical contact separation for PVD aluminum back contact solar cells
2015 Energy Procedia, Band: 67, Seiten: 70 - 75
M. Zhao, X. Y. Guo, O. Ambacher, C. Nebel, R. Hoffmann
Electrochemical generation of hydrogenated graphene flakes
2015 Carbon, Band: 83, Seiten: 128 - 135
D. Backe, F. Balle, D. Eifler
Fatigue testing of CFRP in the Very High Cycle Fatigue (VHCF) regime at ultrasonic frequencies
2015 Compos Sci Technol, Band: 106, Seiten: 93 - 99
Hiermaier S
Foreword. DYMAT 2015 - 11th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading
2015
Feldmann F, Ritzau K.-U., Bivour M, Moldovan A, Modi S, Temmler J, Hermle M, Glunz S
High and low work function materials for passivated contacts
2015 Energy Procedia, Band: 77, Seiten: 263 - 270
Schindler F, Schön J, Michl B, Riepe S, Krenckel P, Benick J, Feldmann F, Hermle M, Glunz S, Warta W, Schubert M
High-efficiency multicrystalline silicon solar cells: Potential of n-type doping
2015 IEEE Journal of Photovoltaics, Band: 5, Nummer: 6, Seiten: 1571 - 1579
Schindler F., Schön J., Michl B., Riepe S., Krenckel P., Benick J., Feldmann F., Hermle M., Glunz S., Warta W., Schubert M.
High-efficiency multicrystalline silicon solar cells: Potential of n-type doping.
2015 IEEE Journal of Photovoltaics, Band: 5, Nummer: 6, Seite: 1571–1579
KurzfassungIn this study, we demonstrate the potential of multicrystalline (mc) n-type silicon for the fabrication of highly efficient mc-Si solar cells. High-quality mc n-type silicon wafers are obtained from a research ingot crystallized in a high-purity crucible, using high-purity granular silicon as seed layer in the crucible bottom and high-purity polysilicon feedstock for the block. An mc p-type silicon block crystallized under identical conditions (same seed and feedstock, crucible system, and temperature profiles) serves as reference and enables measurements of the interstitial iron and chromium concentrations by metastable defect imaging. In combination with 2-D simulations for in-diffusion and precipitation of chromium, the limitation of n-type high-performance mc silicon by these metals is assessed after different solar cell processing steps. Material-related efficiency losses are assessed by an “efficiency limiting bulk recombination analysis,” which combines injection-dependent photoluminescence imaging of minority charge carrier diffusion length with PC1D cell simulations. Finally, based on this material, boron-diffused front-junction mc n-type silicon solar cells with a full-area passivated rear contact (TOPCon) are fabricated. The record cell features an efficiency of 19.6%, which is the highest efficiency reported for an mc n-type silicon solar cell.
Carrubba V, Maroldt S, Musser M, Ture E, Dammann M, van Raay F, Quay R, Brückner P, Ambacher O
High-efficiency, high-temperature continuous class-E sub-waveform solution AlGaN/GaN power amplifier
2015 IEEE, Band: 25, Nummer: 8, Seiten: 526 - 528
E. Ture, D. Schwantuschke, A. Tessmann, S. Wagner, P. Bruckner, M. Mikulla, R. Quay, O. Ambacher
High-gain AlGaN/GaN HEMT single chip E-band power amplifier MMIC with 30 dBm output power
2015 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
J. Chéron, M. Campovecchio, R. Quéré, D. Schwantuschke, R. Quay, O. Ambacher
High-gain over 30% PAE power amplifier MMICs in 100 nm GaN technology at Ka-band frequencies
2015 10th European Microwave Integrated Circuits Conference (EuMIC), Seiten: 262 - 264
M. Wespel, M. Dammann, V. Polyakov, R. Reiner, P. Waltereit, B. Weiss, R. Quay, M. Mikulla, O. Ambacher
High-voltage stress time-dependent dispersion effects in AlGaN/GaN HEMTs
2015 IEEE International Reliability Physics Symposium
Schön J., Schindler F., Kwapil W., Knörlein M., Krenckel P., Riepe S., Warta W., Schubert M.
Identification of the most relevant metal impurities in mc n-type silicon for solar cells
2015 Solar Energy Materials and Solar Cells, Band: 142, Seite: 107–115
KurzfassungIn general, the charge carrier lifetime in n-type silicon is less sensitive to common dissolved metals compared to p-type silicon. However, in experiments it was observed that metal impurities limit the lifetime in n-type multicrystalline (mc) silicon even if high purity feedstock was used. By evaluating Neutron Activation Analysis (NAA) and Inducitvely Coupled Plasma Mass Spectrometry (ICP-MS) at blocks grown with high purity feedstock, we identified the main currently unavoidable metal impurities present in n-type mc silicon. In addition, we measured the charge carrier lifetime on surface-passivated wafers after different solar cell processes. The measurements were compared to simulations in order to identify the limitations by different impurities and to evaluate the influence of metal precipitates. We found that Cri is an important defect in good grains of as-grown wafers. Dissolved Co can have a severe impact on lifetime after process steps with fast cooling. The lower lifetime in the edge region of the blocks is attributed to FeSi2 precipitates, which explains the poor gettering response of the edge region in contrast to grains in the block center. From the results obtained for FeSi2-precipitates, we concluded that Cu3Si- and NiSi2-precipitates located at crystal defects may be responsible for significant recombination in the block center.
B Amado-Rey, Y Campos-Roca, R Weber, S Maroldt, A Tessmann, H Massler, S Wagner, A Leuther, O Ambacher
Impact of metallization layer structure on the performance of G-Band branch-line couplers
2015 IEEE Microw Wirel Co, Band: 25, Nummer: 12, Seiten: 793 - 795
N. Espinosa, S. U. Schwarz, A. Podolska, O. Ambacher
Impedance characterization of DNA-functionalization layers on AlGaN/GaN high electron mobility transistors
2015 Procedia Engineering, Band: 120, Seiten: 912 - 915
GanzenmĂźller G, Hiermaier S, May M
Improvements to the prototype micro-brittle model of peridynamics
2015 , Seiten: 163 - 183
KurzfassungThis paper assesses the accuracy and convergence of the bond-based Peridynamic model with brittle failure, known as the prototype micro-brittle (PMB) model. We investigate the discrete equations of this model, suitable for numerical implementation. It is shown that the widely used discretization approach incurs rather large errors. Motivated by this observation, a correction is proposed, which significantly increases the accuracy by cancelling errors associated with the discretization. As an additional result, we derive equations to treat the interactions between differently sized particles, i.e., a non-homogeneous discretization spacing. This presents an important step forward for the applicability of the PMB model to complex geometries, where it is desired to model interesting parts with a fine resolution (small particle spacings) and other parts with a coarse resolution in order to gain numerical efficiency. Validation of the corrected Peridynamic model is performed by comparing longitudinal sound wave propagation velocities with exact theoretical results. We find that the corrected approach correctly reproduces the sound wave velocity, while the original approach severely overestimates this quantity. Additionally, we present simulations for a crack growth problem which can be analytically solved within the framework of Linear Elastic Fracture Mechanics Theory. We find that the corrected Peridynamics model is capable of quantitatively reproducing crack initiation and propagation.
R. Reiner, P. Waltereit, B. Weiss, M. Wespel, R. Quay, M. Schlechtweg, M. Mikulla, O. Ambacher
Integrated reverse-diodes for GaN-HEMT structures
2015 IEEE 27th International Symposium on Power Semiconductor Devices & IC's (ISPSD), Seiten: 45 - 48
Kraft A, Labusch L, Ensslen T, Dürr I, Bartsch J, Glatthaar M, Glunz S, Reinecke H
Investigation of acetic acid corrosion impact on printed solar cell contacts
2015 IEEE Journal of Photovoltaics, Band: 5, Nummer: 3, Seiten: 736 - 743
M. Klenner, T. Abels, C. Zech, A. Hülsmann, M. Schlechtweg, O. Ambacher
Investigation of dielectric properties of multilayer structures consisting of homogeneous plastics and liquid solutions at 75–110 GHz
2015 Journal of Sensors and Sensor Systems, Band: 4, Nummer: 1, Seiten: 125 - 131
Vignjevic R, Hughes K, Vuyst T, Djordevic N, Campbell J, Stojkovic M, Gulavani O, Hiermaier S
Lagrangian analysis led design of a shock recovery plate impact experiment
2015 International Journal of Impact Engineering, Band: 77, Seiten: 16 - 29
KurzfassungShock recovery techniques, such as the flyer-plate impact test, are used to examine a material that has been subjected to a single well-defined shock, followed by a single release wave. One of the key requirements of this type of technique is that the process should be such that any change found in the sample after recovery, can only be attributed to the shock process alone. Therefore, the principal problem for a test specimen-fixture assembly is that it is designed such that the loading history of the recovered specimen is known. This has motivated this research through the analysis led design of a shock recovery experiment. The choice of Lagrangian Finite Element Analysis for this design work was driven by the method’s ability to accurately track history variables (for plastic deformation) and treat contact interactions which are crucial in this problem. //Starting from an initial configuration, LS-Dyna has been used to analyse in detail the resulting wave propagation to ensure the generation of a uniaxial strain state in the specimen through Lagrangian distance-time diagrams. These iso-maps enabled the identification of potential shortcomings with the initial design, in terms of the transmission of contact and the influence of radial release waves at the different boundaries between specimen and supporting fixture rings. //The benefits of using Lagrangian Finite Element Analysis for this design work are its ability to track history variables (for plastic deformation) and contact treatment. Based on these findings, a new configuration was developed, which consists of an array of concentric rings that support the specimen. During shock formation in the specimen, these rings progressively transfer the loading in the impact direction and radially away from the specimen, acting as momentum traps and preventing unwanted release waves from affecting the strain state experienced by the specimen. //Comparing distance time diagrams between original and proposed configurations, a design sensitivity analysis was performed, where the new geometry resulted in a decrease of both the residual velocity (â38%) and radial displacement (â27%) of the target when compared to the original setup.
Vignjevic, R., Hughes, K., Vuyst, T. de, Djordevic, N., Campbell, J., Stojkovic, M., Gulavani, O., Hiermaier, S.
Lagrangian analysis led design of a shock recovery plate impact experiment
2015 International Journal of Impact Engineering, Band: 77, Seiten: 16 - 29
KurzfassungShock recovery techniques, such as the flyer-plate impact test, are used to examine a material that has been subjected to a single well-defined shock, followed by a single release wave. One of the key requirements of this type of technique is that the process should be such that any change found in the sample after recovery, can only be attributed to the shock process alone. Therefore, the principal problem for a test specimen-fixture assembly is that it is designed such that the loading history of the recovered specimen is known. This has motivated this research through the analysis led design of a shock recovery experiment. The choice of Lagrangian Finite Element Analysis for this design work was driven by the method's ability to accurately track history variables (for plastic deformation) and treat contact interactions which are crucial in this problem. //Starting from an initial configuration, LS-Dyna has been used to analyse in detail the resulting wave propagation to ensure the generation of a uniaxial strain state in the specimen through Lagrangian distance-time diagrams. These iso-maps enabled the identification of potential shortcomings with the initial design, in terms of the transmission of contact and the influence of radial release waves at the different boundaries between specimen and supporting fixture rings. //The benefits of using Lagrangian Finite Element Analysis for this design work are its ability to track history variables (for plastic deformation) and contact treatment. Based on these findings, a new configuration was developed, which consists of an array of concentric rings that support the specimen. During shock formation in the specimen, these rings progressively transfer the loading in the impact direction and radially away from the specimen, acting as momentum traps and preventing unwanted release waves from affecting the strain state experienced by the specimen. //Comparing distance time diagrams between original and proposed configurations, a design sensitivity analysis was performed, where the new geometry resulted in a decrease of both the residual velocity (−38%) and radial displacement (−27%) of the target when compared to the original setup.
J. Wallauer, C. Grumber, V. Polyakov, R. Iannucci, V. Cimalla, O. Ambacher, M. Walther
Large area InN terahertz emitters based on the lateral photo-Dember effect
2015 Appl Phys Lett, Band: 107, Nummer: 11
Kraft A, Wolf C, Bartsch J, Glatthaar M, Glunz S
Long term stability of copper front side contacts for crystalline silicon solar cells
2015 Solar Energy Materials and Solar Cells, Band: 136, Seiten: 25 - 31
Terheiden B, Ballmann T, Horbelt R, Schiele Y, Seren S, Ebser J, Hahn G, Mertens V, Koentopp M, Scherff M, Müller J, Holman Z, Descoeudres A, de Wolf S, Geissbuehler J, Ballif C, Weber B, Saint-Cast P, Rauer M, Schmiga C, Glunz S, Morrison D, Devenport S, Antonelli D, Busto C, Grasso F, Ferrazza F, Tonelli E, Oswald W
Manufacturing 100-µm-thick silicon solar cells with efficiencies greater than 20% in a pilot production line
2015 Physica Status Solidi A, Band: 212, Nummer: 1, Seiten: 13 - 24
Dlugosch M, Lukaszewicz D, Fritsch J, Hiermaier S
Mechanical characterization of hybrid material systems consisting of sheet metal and advanced composites
2015
KurzfassungStrip-shaped hybrid coupon specimens comprised of steel and glass/carbon fiber reinforced plastics are tested under quasistatic tension and 3-point-bending. The effects of major material and design parameters (steel and fiber type, laminate thickness and layup) on the stiffness, strength and the specific energy absorption are assessed. Furthermore, hybrid mechanisms resulting from the mutual interaction of both constituent materials are presented. Although anticipated effects on the hybrid specimensâ stiffness and strength are widely confirmed, the fiber type for example exhibits a distinctly smaller impact than expected. The specimensâ loading and failure behavior is rather dominated by the type of steel and its characteristics. Thus, glass fiber reinforced hybrid variants generally keep up with carbon fiber reinforced hybrid variants in terms of mechanical properties. Considering the difference in price, this is of particular interest for hybrid mid or high volume crash structural applications. As hybrid mechanism, a distinct extension of the maximum strain is observed for both composites (up to 48 %) and steel (up to 23 %) when joined in a hybrid specimen and tested under tensile loads. Furthermore, having composites on the rather pressure loaded side in 3-point-bending results in a 26 %-increase in mass specific energy absorption (compared to reverse loading) due to an enhanced composite failure mode and the stabilizing effect of the steel strip.
D. Backe, F. Balle, D. Eifler
Microstructural Characterization of Fatigue Damage of CFRP in the Very High Cycle Fatigue Regime
2015 Advanced Composites for Aerospace, Marine, and Land Applications II, Seiten: 325 - 334
S. Moench, M. Costa, A. Barner, I. Kallfass, R. Reiner, B. Weiss, P. Waltereit, R. Quay, O. Ambacher
Monolithic integrated quasi-normally-off gate driver and 600 V GaN-on-Si HEMT
2015 IEEE 3rd Workshop on Wide Bandgap Power Devices and Applications (WiPDA), Seiten: 92 - 97
P. Dennler, S. Maroldt, R. Quay, O. Ambacher
Monolithic three-stage 6–18GHz high power amplifier with distributed interstage in GaN technology
2015 10th European Microwave Integrated Circuits Conference (EuMIC), Seiten: 29 - 32
B. Weiss, R. Reiner, P. Waltereit, S. Muller, M. Wespel, R. Quay, O. Ambacher
Monolithically-integrated mulitlevel inverter on lateral GaN-on-Si technology for high-voltage applications
2015 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
Dlugosch M, Fritsch J, Lukaszewicz D, Hiermaier S
New method to analyze numerical crash simulation data to assess the suitability of hybrid composite structures in automotive applications
2015
KurzfassungIn order to enhance development processes for multi material vehicle architecture concepts involving composites or hybrid composite-metal material systems a method is presented that aims to rationalize engineering judgements by means of quantifiable criteria for the suitability of a certain hybrid material system for a particular structural application. A number of significant crash load cases for a structure is considered simultaneously by superimposing the output data of several numerical crash simulations and defining criteria to qualify the suitability of a particular hybrid material system. The work introduced here focusses on the analysis of the global anisotropy of the crash loading situation as an indicator for a rather composite- or metal-intensive hybrid material system. The definition of the anisotropy criterion and the implementation of the method into the development infrastructure of automotive engineering is presented. A first step validation using simple flat coupon specimen simulations shows reasonable results and proves the applicability of the method.
B. Hannemann, S. Backe, S. Schmeer, F. Balle, U.P. Breuer
New multifunctional hybrid polymer composites reinforced by carbon and steel fibers
2015 20th international conference on composite materials (ICCM)

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Benkhelifa F, Müller S, Polyakov VM, Ambacher O
Normally-off AlGaN/GaN/AlGaN double heterostructure FETs with a thick undoped GaN gate layer
2015 IEEE, Band: 36, Nummer: 9, Seiten: 905 - 907
F. Thome, S Maroldt, O. Ambacher
Novel destructive-interference-envelope detector for high data rate ASK demodulation in wireless communication receivers
2015 IEEE MTT-S International Microwave Symposium, Seiten: 1 - 4
M. Seelmann-Eggebert, M. Ohlrogge, R. Weber, D. Peschel, H. Massler, M. Riessle, A. Tessmann, A. Leuther, M. Schlechtweg, O. Ambacher
On the accurate measurement and calibration of S-parameters for millimeter wavelengths and beyond
2015 IEEE T Microw Theory, Band: 63, Nummer: 7, Seiten: 2335 - 2341
M. Seelmann-Eggebert, B. Aja, B. Baldischweiler, G. Moschetti, H. Massler, D. Bruch, M. Schlechtweg, O. Ambacher
On the determination of noise parameters of low‐noise transistor devices
2015 Int J Numer Model El, Band: 14
Ganzenmüller G, Hiermaier S, May M
On the similarity of meshless discretizations of Peridynamics and Smooth-Particle Hydrodynamics
2015 Computers and Structures, Band: 150, Seiten: 71 - 78
KurzfassungThis paper discusses the similarity of meshless discretizations of Peridynamics and Smooth-Particle-Hydrodynamics (SPH), if Peridynamics is applied to classical material models based on the deformation gradient. We show that the discretized equations of both methods coincide if nodal integration is used. This equivalence implies that Peridynamics reduces to an old meshless method and all instability problems of collocation-type particle methods apply. These instabilities arise as a consequence of the nodal integration scheme, which causes rank-deficiency and leads to spurious zero-energy modes. As a result of the demonstrated equivalence to SPH, enhanced implementations of Peridynamics should employ more accurate integration schemes.
Ganzenmueller G, Hiermaier S, May M
On the similarity of meshless discretizations of Peridynamics and Smooth-Particle Hydrodynamics
2015 THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND COMPUTERS & STRUCTURES, PERGAMON-ELSEVIER SCIENCE LTD, Band: 150, Seiten: 71 - 78
KurzfassungThis paper discusses the similarity of meshless discretizations of Peridynamics and Smooth-Particle-Hydrodynamics (SPH), if Peridynamics is applied to classical material models based on the deformation gradient. We show that the discretized equations of both methods coincide if nodal integration is used. This equivalence implies that Peridynamics reduces to an old meshless method and all instability problems of collocation-type particle methods apply. These instabilities arise as a consequence of the nodal integration scheme, which causes rank-deficiency and leads to spurious zero-energy modes. As a result of the demonstrated equivalence to SPH, enhanced implementations of Peridynamics should employ more accurate integration schemes. (C) 2015 Elsevier Ltd. All rights reserved.
Ganzenmueller, G.C., Hiermaier, S., May, M.
On the similarity of meshless discretizations of Peridynamics and Smooth-Particle Hydrodynamics
2015 Computers and Structures, Band: 150, Seiten: 71 - 78
KurzfassungThis paper discusses the similarity of meshless discretizations of Peridynamics and Smooth-Particle-Hydrodynamics (SPH), if Peridynamics is applied to classical material models based on the deformation gradient. We show that the discretized equations of both methods coincide if nodal integration is used. This equivalence implies that Peridynamics reduces to an old meshless method and all instability problems of collocation-type particle methods apply. These instabilities arise as a consequence of the nodal integration scheme, which causes rank-deficiency and leads to spurious zero-energy modes. As a result of the demonstrated equivalence to SPH, enhanced implementations of Peridynamics should employ more accurate integration schemes.
Kraft A, Pernia Y, Kalio A, Gautrein A, Ni L, Bartsch J, Glunz S, Reinecke H
Origin of corrosion effects in solar cell contacts during electrochemical nickel deposition
2015 Journal of Applied Electrochemistry, Band: 45, Nummer: 1, Seiten: 95 - 104
E. Ture, P. Brückner, F.V. Raay, R. Quay, O. Ambacher, M. Alsharef, R. Granzner, F. Schwierz
Performance and parasitic analysis of sub-micron scaled tri-gate AlGaN/GaN HEMT design
2015 10th European Microwave Integrated Circuits Conference (EuMIC), Seiten: 97 - 100
Schindler F., Michl B., Kleiber A., Steinkemper H., Schön J., Kwapil W., Krenckel P., Riepe S., Warta W., Schubert M.
Potential gain in multicrystalline silicon solar cell efficiency by n-type doping
2015 IEEE Journal of Photovoltaics, Band: 5, Nummer: 2, Seite: 499–506
KurzfassungThis study aims for a quantitative investigation of the material limitations and the efficiency potential of an entire multicrystalline (mc) n-type silicon block in comparison with an mc p-type block of the same purity level in order to predict the potential of mc n-type silicon for the industrial production of solar cells. Therefore, two standard mc silicon blocks were crystallized under identical conditions (same high purity feedstock, crucible system, and temperature profiles), only differing in their type of doping. The material quality of wafers along the whole block height is analyzed after different solar cell process steps by photoluminescence imaging of the diffusion length. The bulk recombination related efficiency losses are assessed by an “efficiency limiting bulk recombination analysis (ELBA),” combining injection dependent lifetime images with PC1D cell simulations. The influence of the base resistivity variation along the block is considered in the PC1D cell simulations and backed up by Sentaurus Device simulations. This analysis predicts a significantly higher material-related efficiency potential after typical solar cell processes along the whole block height for mc n-type silicon compared with mc p-type silicon. In addition, the efficiency potential for mc n-type silicon depends less on block position.
Tranberg B, Thomsen AB, Rodriguez RA, Andresen GB, Schäfer M, Greiner M
Power flow tracing in a simplified highly renewable European electricity network
2015 New J Phys, Band: 17, Seite: 105002
KurzfassungThe increasing transmission capacity needs in a future energy system raise the question of how associated costs should be allocated to the users of a strengthened power grid. In contrast to straightforward oversimplified methods, a flow tracing based approach provides a fair and consistent nodal usage and thus cost assignment of transmission investments. This technique follows the power flow through the network and assigns the link capacity usage to the respective sources or sinks using a diffusion-like process, thus taking into account the underlying network structure and injection pattern. As a showcase, we apply power flow tracing to a simplified model of the European electricity grid with a high share of renewable wind and solar power generation, based on long-term weather and load data with an hourly temporal resolution.
S. Mönch, M. Costa, A. Barner, I. Kallfass, R. Reiner, B. Weiss, P. Waltereit, R. Quay, O. Ambacher
Quasi-normally-off GaN gate driver for high slew-rate d-mode GaN-on-Si HEMTs
2015 IEEE 27th International Symposium on Power Semiconductor Devices & IC's (ISPSD), Seiten: 372 - 376
A Hülsmann, C Zech, M Klenner, A Tessmann, A Leuther, D Lopez-Diaz, M. Schlechtweg, O. Ambacher
Radar system components to detect small and fast objects
2015 Terahertz Physics, Devices, and Systems IX: Advanced Applications in Industry and Defense
May, Michael, Hesebeck, Olaf, Marzi, Stephan H., Boehme, Wolfgang, Lienhard, Joerg, Kilchert, Sebastian, Brede, Markus, Hiermaier, Stefan
Rate dependent behavior of crash-optimized adhesives - experimental characterization, model development, and simulation
2015 Engineering fracture mechanics, Band: 133, Seiten: 112 - 137
KurzfassungThe mechanical properties of crash-optimized adhesive BETAMATE 1496V are characterized over a wide range of strain rates. The information gathered from the mechanical tests are used for developing a fully rate-dependent constitutive law for cohesive interface elements considering both, the strain rate dependency of the initiation stress and the strain rate dependency of the fracture toughness. The model is calibrated and verified against experimental data for tapered double cantilever beam (TDCB) and tapered end notched flexure (TENF) tests. Finally, the model is validated against quasi-static and dynamic experimental results on an adhesively bonded T-joint. The numerical predictions show good correlation with the experimental results.
May Michael, Hesebeck Olaf, Marzi Stephan, BĂśhme Wolfgang, Lienhard JĂśrg, Kilchert Sebastian, Brede Markus, Hiermaier Stefan
Rate dependent behavior of crash-optimized adhesives â experimental characterization, model development, and simulation
2015 Engineering fracture mechanics, Band: 133, Seiten: 112 - 137
KurzfassungThe mechanical properties of crash-optimized adhesive BETAMATE 1496V are characterized over a wide range of strain rates. The information gathered from the mechanical tests are used for developing a fully rate-dependent constitutive law for cohesive interface elements considering both, the strain rate dependency of the initiation stress and the strain rate dependency of the fracture toughness. The model is calibrated and verified against experimental data for tapered double cantilever beam (TDCB) and tapered end notched flexure (TENF) tests. Finally, the model is validated against quasi-static and dynamic experimental results on an adhesively bonded T-joint. The numerical predictions show good correlation with the experimental results.
N. Espinosa, S. Schwarz, V. Cimalla, O. Ambacher
Sips adsorption model for DNA sensing with AlGaN/GaN high electron mobility transistors
2015 MRS Online Proceedings Library Archive, Band: 1763
B. Weiss, R. Reiner, R. Quay, P. Waltereit, F. Benkhelifa, M. Mikulla, M. Schlechtweg, O. Ambacher
Switching frequency modulation for GaN-based power converters
2015 IEEE Energy Conversion Congress and Exposition (ECCE), Seiten: 4361 - 4366
Hahn Herwig, Benkhelifa Fouad, Ambacher Oliver, Brunner Frank, Noculak Achim, Kalisch Holger, Vescan Andrei
Threshold voltage engineering in GaN-based HFETs: A systematic study with the threshold voltage reaching more than 2 V
2015 IEEE, Band: 62, Nummer: 2, Seiten: 538 - 545
V. Zuerbig, D. Pätz, J. Fries, M. Bichra, W. Pletschen, K. Holc, M. Reusch, C.E. Nebel, S. Sinzinger, O. Ambacher, V. Lebedev
Tunable multisegment SixNy/AlN piezo lenses for wavefront correction
2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), Seiten: 2045 - 2048
Reichel C, Feldmann F, Müller R, Reedy R, Lee B, Young D, Stradins P, Hermle M, Glunz S
Tunnel oxide passivated contacts formed by ion implantation for applications in silicon solar cells
2015 Journal of Applied Physics, Band: 118, Nummer: 20
F. Balle, J. Magin
Ultrasonic spot and torsion welding of aluminum to titanium alloys: Process, properties and interfacial microstructure
2015 Physics Procedia, Band: 70, Seiten: 846 - 849
F. Benkhelifa, S. Müller, V.M. Polyakov, S. Breuer, H. Czap, C. Manz, M. Mikulla, O. Ambacher
Vertical buffer leakage and temperature effects on the breakdown performance of GaN/AlGaN HEMTs on Si substrate
2015 ECS Transactions, Band: 69, Nummer: 11, Seiten: 65 - 70
M. Baeumler, M. Dammann, M. Wespel, R. George, H. Konstanzer, S. Maroldt, V. M. Polyakov, S. Müller, W. Bronner, P. Brückner, F. Benkhelifa, P. Waltereit, R. Quay, M. Mikulla, J. Wagner, O. Ambacher, A. Graff, F. Altmann, M. Simon-Najasek, M. Lorenzini, M. Fagerlind, P. J. van der Wel, T. Roedle
With electroluminescence microcopy towards more reliable AlGaN/GaN transistors
2015 Optical Sensing, Imaging, and Photon Counting: Nanostructured Devices and Applications

2014

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A. Leuther, A. Tessmann, P. Doria, M. Ohlrogge, M. Seelmann-Eggebert, H. Maßler, M. Schlechtweg, O. Ambacher
20 nm Metamorphic HEMT technology for terahertz monolithic integrated circuits
2014 9th European Microwave Integrated Circuit Conference, Seiten: 84 - 87
Bartsch J, Kamp M, Hartleb D, Wittich C, Mondon A, Steinhauser B, Feldmann F, Richter A, Benick J, Glatthaar M, Hermle M, Glunz Stefan
21.8% efficient n-type solar cells with industrially feasible plated metallization
2014 Energy Procedia, Band: 55, Seiten: 400 - 409
Tessmann Axel, Hurm Volker, Leuther Arnulf, Massler Hermann, Weber Rainer, Kuri Michael, Riessle Markus, Stulz Hans-Peter, Zink Martin, Schlechtweg Michael
243 GHz low-noise amplifier MMICs and modules based on metamorphic HEMT technology
2014 Cambridge University Press, Band: 6, Nummer: 3-4, Seiten: 215 - 223
A. Tessmann, A. Leuther, H. Massler, V. Hurm, M. Kuri, M. Zink, M. Riessle, H.P. Stulz, M. Schlechtweg, O. Ambacher
A 600 GHz low-noise amplifier module
2014 IEEE MTT-S International Microwave Symposium (IMS2014), Seiten: 1 - 3
R. Weber, D. Schwantuschke, P. Brückner, R. Quay, F. van Raay, O. Ambacher
A 92 GHz GaN HEMT voltage-controlled oscillator MMIC
2014 IEEE MTT-S International Microwave Symposium (IMS2014), Seiten: 1 - 4
A Tessmann, A Leuther, V Hurm, H Massler, S Wagner, M Kuri, M Zink, M Riessle, H-P Stulz, M Schlechtweg, O Ambacher
A broadband 220-320 ghz medium power amplifier module
2014 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
F Thome, S Maroldt, M Schlechtweg, O Ambacher
A low-power W-band receiver MMIC for amplitude modulated wireless communication up to 24 Gbit/s
2014 Asia-Pacific Microwave Conference, Seiten: 1073 - 1075
S. Maroldt, P. Brückner, R. Quay, O. Ambacher
A microwave high-power GaN transistor with highly-integrated active digital switch-mode driver circuit
2014 IEEE MTT-S International Microwave Symposium (IMS2014), Seiten: 1 - 4
M. Ohlrogge, M. Seelmann-Eggebert, A. Leuther, H. Maβler, A. Tessmann, R. Weber, D. Schwantuschke, M. Schlechtweg, O. Ambacher
A scalable compact small-signal mHEMT model accounting for distributed effects in sub-millimeter wave and terahertz applications
2014 IEEE MTT-S International Microwave Symposium (IMS2014), Seiten: 1 - 4
T. Maier, V. Carrubba, R. Quay, F. van Raay, O Ambacher
Active harmonic source-/load-pull measurements of AlGaN/GaN HEMTs at X-band frequencies
2014 83rd ARFTG Microwave Measurement Conference, Seiten: 1 - 4
May M, Nossek M, Petrinic N, Hiermaier S, Thoma K
Adaptive multi-scale modeling of high velocity impact on composite panels
2014 Composites. Part A, Applied science and manufacturing, Band: 58, Seiten: 56 - 64
KurzfassungA computationally efficient adaptive multi-scale methodology for modeling composites under high rates of loading is proposed. The physically based model relies on micromechanical properties of the constituents only. The adaptive algorithm switches between two different constitutive laws. Initially, the material response is calculated based on effective linear-elastic, orthotropic material properties at the ply scale which are calculated using the rule of mixtures. A modified Hashin-Rotem criterion is then used to identify the switch to a more accurate micromechanical analysis based on the generalized method of cells (GMC). The methodology is verified by simulating tensile tests on laminates with different stacking sequences. Finally the model validated against experimental data for high-velocity impact on quasi-isotropic composite targets taken from the literature in order to illustrate the efficiency and accuracy of the proposed methodology.
May, M., Nossek, M., Petrinic, N., Hiermaier, S., Thoma, K.
Adaptive multi-scale modeling of high velocity impact on composite panels
2014 Composites. Part A, Applied science and manufacturing, Band: 58
KurzfassungA computationally efficient adaptive multi-scale methodology for modeling composites under high rates of loading is proposed. The physically based model relies on micromechanical properties of the constituents only. The adaptive algorithm switches between two different constitutive laws. Initially, the material response is calculated based on effective linear-elastic, orthotropic material properties at the ply scale which are calculated using the rule of mixtures. A modified Hashin-Rotem criterion is then used to identify the switch to a more accurate micromechanical analysis based on the generalized method of cells (GMC). The methodology is verified by simulating tensile tests on laminates with different stacking sequences. Finally the model validated against experimental data for high-velocity impact on quasi-isotropic composite targets taken from the literature in order to illustrate the efficiency and accuracy of the proposed methodology.
V. Carrubba, E. Ture, R. Quay, F. van Raay, M. Musser, O. Ambacher
Analysis and performance of drain bias “in-dependent” Class-J power amplifier
2014 Asia-Pacific Microwave Conference, Seiten: 998 - 1000
M. Klenner, C. Zech, A. Huelsmann, M. Schlechtweg, J. Wagner, O. Ambacher
Analysis of dielectric properties of layered plastics at w-band frequencies Sensors and Measuring Systems
2014 17. ITG/GMA Symposium, Seiten: 1 - 4
Schiefer S, Zimmermann B, Glunz S, Würfel U
Applicability of the Suns-VOC method on organic solar cells
2014 IEEE Journal of Photovoltaics, Band: 4, Nummer: 1, Seiten: 271 - 277
F. v. Raay, R. Quay, M. Seelmann-Eggebert, D. Schwantuschke, D. Peschel, M.l Schlechtweg, O. Ambacher
Automatic extraction of analytical large-signal FET models with parameter estimation by function decomposition
2014 9th European Microwave Integrated Circuit Conference, Seiten: 202 - 205
T. Merkle, A. Leuther, S. Koch, I. Kallfass, A. Tessmann, S. Wagner, H. Massler, M. Schlechtweg, O. Ambacher
Backside process free broadband amplifier MMICs at D-Band and H-Band in 20 nm mHEMT technology
2014 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
E. Ture, V. Carrubba, S. Maroldt, M. Musser, H. Walcher, R. Quay, O. Ambacher
Broadband 1.7–2.8 GHz high-efficiency (58%), high-power (43 dBm) Class-BJ GaN power amplifier including package engineering
2014 9th European Microwave Integrated Circuit Conference, Seiten: 345 - 348
Feldmann F, Simon M, Bivour M, Reichel C, Hermle M, Glunz S
Carrier-selective contacts for Si solar cells
2014 Applied Physics Letters, Band: 104, Nummer: 18
W. Pletschen, L. Kirste, V. Cimalla, S. Müller, M. Himmerlich, S. Krischok, O. Ambacher
Changes of electronic properties of AlGaN/GaN HEMTs by surface treatment
2014 MRS Online Proceedings Library Archive, Seite: 1736
B. Weiss, R. Reiner, R. Quay, P. Waltereit, S. Müller, F. Benkhelifa, M. Mikulla, M. Schlechtweg, O. Ambacher
Characterization of AlGaN/GaN-on-Si HFETs in high-power converter applications
2014 16th European Conference on Power Electronics and Applications, Seiten: 1 - 10
O. Ambacher, R. Ostendorf, D. Bleh, A. Merten, J. Grahmann, R. Schmidt, M. Kunzer, S. Hugger, J. Wagner
Combining external cavity quantum cascade lasers and MOEMS technology: an approach for miniaturization and fast wavelength scanning
2014 International Conference on Optical MEMS and Nanophotonics, Seiten: 91 - 92
M. Klenner, C. Zech, A. Hülsmann, M. Schlechtweg, O. Ambacher
Compact quasi-optical focusing system for a 94 GHz FMCW radar
2014 15th International Radar Symposium (IRS), Seiten: 1 - 3
M. Kotiranta, D. Bruch, A. Leuther, H. Massler, M. Seelmann-Eggebert, M. Schlechtweg, O. Ambacher, S. Türk, J. Goliasch, F. Schäfer2
Cryogenic low noise amplifier development for 67–116 GHz
2014 39th International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz), Seiten: 1 - 2
Feldmann Frank, Simon Maik, Bivour Martin, Reichel Christian, Hermle Martin, Glunz Stefan
Efficient carrier-selective p- and n-contacts for Si solar cells
2014 Solar Energy Materials and Solar Cells, Band: 131, Nummer: 0, Seiten: 100 - 104
Reiterer, A.
Effizientes Monitoring von Schienennetzen: Mobiles Laser-Scanning löst konventionelle Messmethoden ab
2014 Ingenieurspiegel, Band: Nr. 2
V. Zuerbig, J. Hees, W. Pletschen, R.E. Sah, M. Wolfer, L. Kirste, N. Heidrich, C.E. Nebel, O. Ambacher, V. Lebedev
Elastic properties of ultrathin diamond/AlN membranes
2014 Thin Solid Films, Band: 558, Seiten: 267 - 271
M. Baeumler, V. Polyakov, F. Gütle, M. Dammann, F. Benkhelifa, P. Waltereit, R. Reiner, S. Müller, M. Wespel, R. Quay, M. Mikulla, J. Wagner, O. Ambacher
Electroluminescence investigation of the lateral field distribution in AlGaN/GaN HEMTs for power applications
2014 Acta Phys Pol A, Band: 125, Nummer: 4, Seiten: 982 - 985
S Shokhovets, F. Bärwolf, G. Gobsch, E. Runge, K. Köhler, O. Ambacher
Excitons and exciton‐phonon coupling in the optical response of GaN
2014 physica status solidi (c), Band: 11, Nummer: 2, Seiten: 297 - 301
B. Méndez, K. Lorenz, B. Fraboni, O. Ambacher
Functional Nanowires: Synthesis, Characterization and Applications
2014 physica status solidi (c), Band: 11, Nummer: 2, Seiten: 313 - 314
R. Aidam, E. Diwo, B.-J. Godejohann, L. Kirste, R. Quay, O. Ambacher
Growth model investigation for AlN/Al(Ga)InN interface growth by plasma-assisted molecular beam epitaxy for high electron mobility transistor applications
2014 Phys Status Solidi A, Band: 211, Nummer: 12, Seiten: 2854 - 2860
I. Kallfass, G. Eren, R. Weber, S. Wagner, D. Schwantuschke, R. Quay, O. Ambacher
High linearity active GaN-HEMT down-converter MMIC for E-band radar applications
2014 9th European Microwave Integrated Circuit Conference, Seiten: 128 - 131
Kwapil W., Schon J., Schindler F., Warta W., Schubert M.
Impact of iron precipitates on carrier lifetime in As-grown and phosphorus-gettered multicrystalline silicon wafers in model and experiment
2014 IEEE Journal of Photovoltaics, Band: 4, Nummer: 3, Seite: 791–798
KurzfassungThe impact of iron point defects on the measured injection-dependent minority carrier lifetime in silicon after different processing steps (described by the Shockley-Read-Hall equation) is well known. However, in some parts of multicrystalline silicon (mc-Si) (used for solar cells), a large share of the iron atoms is precipitated. In this study, we simulate realistic iron precipitate distributions in mc-Si after crystallization, as well as after phosphorus diffusion gettering within grains by employing the Fokker-Planck equations. Taking the Schottky contact between metallic precipitates and semiconductor into account, in a second step, we analyze the effect of recombination at iron precipitates on carrier lifetime by means of finite-element simulations. The results are compared with experimental injection-dependent lifetime measurements on a p-type mc-Si wafer before and after phosphorus diffusion. Our simulations show that in the low-lifetime edge region close to the crucible wall, a considerable share of the carrier recombination can be attributed to iron precipitates in both the as-grown and in the phosphorus-diffused state. In addition, the simulated injection dependences of iron precipitates and iron interstitials differ significantly, with the precipitates influencing the carrier lifetime especially in the mid- to high-injection range, which is supported by carrier lifetime measurements.
D. Schwantuschke, B. Aja, M. Seelmann-Eggebert, R. Quay, A. Leuther, P. Brückner, M. Schlechtweg, M. Mikulla, I. Kallfass, O. Ambacher
Improved AlGaN pin photodetectors for monitoring of ultraviolet radiation
2014 IEEE MTT-S International Microwave Symposium (IMS2014), Seiten: 1 - 4
Isakov Matti, Hiermaier Stefan, Kuokkala Veli-Tapani
Improved specimen recovery in tensile split Hopkinson bar
2014 Philosophical Transactions of the Royal Society of London. Series A, Band: 372, Nummer: 2023
KurzfassungThis paper presents an improved specimen recovery method for the tensile split Hopkinson bar (TSHB) technique. The method is based on the trapping of residual stress waves with the use of momentum trap bars. As is well known, successful momentum trapping in TSHB is highly sensitive to experimental uncertainties, especially on the incident bar side of the set-up. However, as is demonstrated in this paper, significant improvement in the reliability of specimen recovery is obtained by using two momentum trap bars in contact with the incident bar. This makes the trapping of the reflected wave insensitive to striker speed and removes the need for a precision set gap between the incident bar and the momentum trap.
Isakov, Matti, Hiermaier, Stefan, Kuokkala, Veli-Tapani
Improved specimen recovery in tensile split Hopkinson bar
2014 Philosophical Transactions of the Royal Society of London. Series A, Band: 372, Seite: Art. 20130194
KurzfassungThis paper presents an improved specimen recovery method for the tensile split Hopkinson bar (TSHB) technique. The method is based on the trapping of residual stress waves with the use of momentum trap bars. As is well known, successful momentum trapping in TSHB is highly sensitive to experimental uncertainties, especially on the incident bar side of the set-up. However, as is demonstrated in this paper, significant improvement in the reliability of specimen recovery is obtained by using two momentum trap bars in contact with the incident bar. This makes the trapping of the reflected wave insensitive to striker speed and removes the need for a precision set gap between the incident bar and the momentum trap.
K. Holc, A. Jakob, T. Weig, K. Köhler, O. Ambacher, U.T. Schwarz
Influence of surface roughness on the optical mode profile in GaN-based violet ridge waveguide laser diodes
2014 Novel In-Plane Semiconductor Lasers XIII, Band: 9002
Wespel Matthias, Baeumler M, Polyakov Vladimir, Dammann M, Reiner Richard, Waltereit Patrick, Quay Rüdiger, Mikulla Michael, Ambacher Oliver
Influence of surface states on the voltage robustness of AlGaN/GaN HFET power devices
2014 Elsevier, Band: 54, Nummer: 12, Seiten: 2656 - 2661
Kraft A, Wolf C, Lorenz A, Bartsch J, Glatthaar M, Glunz Stefan
Long term stability analysis of copper front side metallization for silicon solar cells
2014 Energy Procedia, Band: 55, Seiten: 478 - 485
F. Thome, A. Leuther, S. Maroldt, M. Schlechtweg, O. Ambacher
Low-Power Wireless Data Transmitter MMIC with Data Rates up to 25 Gbit/s and 9.5 mW power consumption using a 113 GHz carrier
2014 IEEE MTT-S International Microwave Symposium (IMS2014), Seiten: 1 - 4
V. Lebedev, D. Iankov, N. Heidrich, V. Zuerbig, C. Wild, V. Cimalla, O. Ambacher
Nano-diamond based spheres for radio frequency electromechanical resonators
2014 IOP Publishing, Band: 24, Nummer: 4
Mondon A, Wang D, Zuschlag A, Bartsch J, Glatthaar M, Glunz Stefan
Nanoscale investigation of the interface situation of plated nickel and thermally formed nickel silicide for silicon solar cell metallization
2014 Applied Surface Science, Band: 323, Seiten: 31 - 39
R. Reiner, P. Waltereit, F. Benkhelifa, H. Walcher, R. Quay, M. Schlechtweg, O. Ambacher
Novel layout and packaging for lateral, low-resistance GaN-on-Si power transistors
2014 8th International Conference on Integrated Power Electronics Systems (CIPS 2014), Seiten: 1 - 5
Rüdiger M, Steinkemper H, Hermle M, Glunz S
Numerical current density loss analysis of industrially relevant crystalline silicon solar cell concepts
2014 IEEE Journal of Photovoltaics, Band: 4, Nummer: 2, Seiten: 533 - 539
Feldmann F, Bivour M, Reichel C, Hermle M, Glunz Stefan
Passivated rear contacts for high-efficiency n-type Si solar cells providing high interface passivation quality and excellent transport characteristics
2014 Solar Energy Materials and Solar Cells, Band: 120, Seiten: 270 - 274
Richter A, Benick J, Kimmerle A, Hermle M, Glunz S
Passivation of phosphorus diffused silicon surfaces with Al2O3: Influence of surface doping concentration and thermal activation treatments
2014 Journal of Applied Physics, Band: 116, Nummer: 24
F. Thome, A. Leuther, S. Maroldt, M. Schlechtweg, O. Ambacher
Planar zero bias Schottky diodes on an InGaAs metamorphic HEMT MMIC process
2014 IEEE Microw Wirel Co, Band: 24, Nummer: 12, Seiten: 860 - 862
Kamp M, Bartsch J, Keding R, Jahn M, Müller R, Glatthaar M, Glunz Stefan, Krossing I
Plating processes on aluminum and application to novel solar cell concepts
2014 Energy Procedia, Band: 55, Seiten: 679 - 687
May M, VoĂ H, Hiermaier S
Predictive modeling of damage and failure in adhesively bonded metallic joints using cohesive interface elements
2014 International journal of adhesion and adhesives, Band: 49, Seiten: 7 - 17
KurzfassungA rate-dependent constitutive law for cohesive interface elements is introduced for the adhesive considering both, the rate dependency of the initiation stress and the rate dependency of the fracture toughness. The model is calibrated with experimental data available from the literature and validated against novel quasi-static and dynamic experimental results on an adhesively bonded T-joint made from high strength steel DP-K 30/50 and crash-optimized adhesive BETAMATE 1496V. The numerical predictions show an excellent correlation with the experimental results.
May, M., Voss, H., Hiermaier, S.
Predictive modeling of damage and failure in adhesively bonded metallic joints using cohesive interface elements
2014 International journal of adhesion and adhesives, Band: 49
KurzfassungA rate-dependent constitutive law for cohesive interface elements is introduced for the adhesive considering both, the rate dependency of the initiation stress and the rate dependency of the fracture toughness. The model is calibrated with experimental data available from the literature and validated against novel quasi-static and dynamic experimental results on an adhesively bonded T-joint made from high strength steel DP-K 30/50 and crash-optimized adhesive BETAMATE 1496V. The numerical predictions show an excellent correlation with the experimental results.
D. Iankov, V. Zürbig, W. Pletschen, C. Giese, R. Iannucci, O. Ambacher, V. Lebedev
Processing of nanoscale gaps for boron-doped nanocrystalline diamond based MEMS
2014 Procedia Engineering, Band: 87, Seiten: 903 - 906
Schuldis D, Richter A, Benick J, Saint-Cast P, Hermle M, Glunz S
Properties of the c-Si/Al2O3 interface of ultrathin atomic layer deposited Al2O3 layers capped by SiNx for c-Si surface passivation
2014 Applied Physics Letters, Band: 105, Nummer: 23
D. Schwantuschke, B. Aja, M. Seelmann-Eggebert, R. Quay, A. Leuther, P. Brückner, M. Schlechtweg, M. Mikulla, I. Kallfass, O. Ambacher
Q-and E-band amplifier MMICs for satellite communication
2014 IEEE MTT-S International Microwave Symposium (IMS2014), Seiten: 1 - 4
Richter A, Benick J, Hermle M, Glunz Stefan
Reaction kinetics during the thermal activation of the silicon surface passivation with atomic layer deposited Al2O3
2014 Applied Physics Letters, Band: 104, Nummer: 6
Carrubba Vincenzo, Maroldt Stephan, Mußer Markus, Walcher Herbert, Van Raay Friedbert, Quay Rüdiger, Ambacher Oliver, Wiegner Dirk, Seyfried Ulrich, Bohn Thomas
Realization of a 30-W highly efficient and linear reconfigurable dual-band power amplifier using the continuous mode approach
2014 Cambridge University Press, Band: 6, Nummer: 2, Seiten: 115 - 128
M. Dammann, M. Baeumler, R. Anto, H. Konstanzer, P. Bruckner, V. Polyakov, M. Wespel, S. Müller, D. Schwantuschke, S. Maroldt, R. Quay, M. Mikulla, O. Ambacher
Reliability of GaN HEMTs with a 100 nm gate length under DC-stress tests
2014 IEEE International Integrated Reliability Workshop Final Report (IIRW), Seiten: 115 - 118
Bivour M, Schröer S, Hermle M, Glunz S
Silicon heterojunction rear emitter solar cells: Less restrictions on the optoelectrical properties of front side TCOs
2014 Solar Energy Materials and Solar Cells, Band: 122, Seiten: 120 - 129
J. Stehle, V.A. Hong, A. Feyh, G.J. O’Brien, G. Yama, O. Ambacher, B. Kim, T.W. Kenny
Silicon migration of through-holes in single-and poly-crystalline silicon membranes
2014 Proc. Solid-State Sensors, Actuat., Microsystems Workshop, Hilton Head, Seiten: 32 - 35
Dimeas A, Drenkard S, Hatziargyriou N, Karnouskos S, Kok K, Ringelstein J, Weidlich A
Smart Houses in the Smart Grid: Developing an interactive network.
2014 IEEE Electrification Magazine, Band: 2, Nummer: 1, Seiten: 81 - 93
Schindler F., Michl B., Schon J., Kwapil W., Warta W., Schubert M.
Solar Cell Efficiency Losses Due to Impurities From the Crucible in Multicrystalline Silicon
2014 IEEE Journal of Photovoltaics, Band: 4, Nummer: 1, Seite: 122–129
KurzfassungThe electrical material quality of multicrystalline (mc) silicon for photovoltaic applications suffers from crystal defects as well as from impurities that originate from the feedstock, the quartz crucible, and its coating. In this study, we investigate the influence of impurities from the crucible on efficiency losses in mc silicon solar cells, focusing on the limitation due to iron. The applicability of p-type mc silicon, crystallized in G1 sized crucibles of industrial material quality and very pure electrically fused silica, for a high-efficiency solar cell process is examined by measuring lifetime and interstitial iron concentration in the wafers after different processing steps and by estimating the cell efficiency potential from injection-dependent bulk lifetime measurements. Interstitial iron concentrations extracted from 2-D simulations of iron precipitation at crystal defects and gettering during processing agree well with Fe<sub>i</sub> measurements at different process stages and explain the observations. Efficiency losses are quantified to losses due to segregated impurities diffused into the silicon melt, losses due to decorated crystal defects and losses due to solid-state diffusion into the crystal. By using a high-purity crucible, losses are reduced significantly and an efficiency gain of 0.5% absolute is estimated to be attainable on wafers with edge region.
J. Magin, F. Balle
Solid state joining of aluminum, titanium and their hybrids by ultrasonic torsion welding: Fügen von Aluminium, Titan und deren Mischverbunde durch Ultraschalltorsionsschweißen
2014 Materialwiss Werkst, Band: 45, Nummer: 12, Seiten: 1072 - 1083
V. Carrubba, R. Quay, S. Maroldt, M. Musser, F. v. Raay, O. Ambacher
Source/Load Pull Investigation of AlGaN/GaN Power Transistors with Ultra-High Efficiency
2014 German Microwave Conference (GeMiC 2014), Seiten: 1 - 4
Tamari Y, Gautrein A, Schmiga C, Binder S, Glatthaar M, Glunz Stefan
Synthesis of a Lead- and Particle-free Metal-organic Ink for Front Side Metallization of Crystalline Silicon Solar Cells
2014 Energy Procedia, Band: 55, Seiten: 708 - 714
Schindler F., Forster M., Broisch J., Schön J., Giesecke J., Rein S., Warta W., Schubert M.
Towards a unified low-field model for carrier mobilities in crystalline silicon
2014 Solar Energy Materials and Solar Cells, Band: 131, Seite: 92–99
KurzfassungThe electrical properties of crystalline silicon crucially depend on the mobility of minority and majority charge carriers. As parameters like the conductivity and the diffusion length are directly connected to carrier mobility, its exact prediction is essential for device simulation and material characterization. While generally accepted mobility models exist for uncompensated silicon, strong deviations have been observed in compensated silicon depending on the compensation level. Different approaches have been suggested for modeling majority carrier mobility correcting for compensation. In this work, the controversially discussed physical reasons for mobility reductions in compensated silicon are critically reviewed and we present a unified description of mobility in silicon. Based on the approach suggested by Schindler et al. [Solar Energy Materials and Solar Cells 106 (2012) 31–36], which describes the modeling of majority carrier mobilities in p-type compensated silicon at room temperature, the model is extended to both majority and minority carrier mobilities in p- and n-type compensated silicon at room temperature and a description for the temperature dependence is suggested. Fit parameters are obtained based on a wide range of published and new carrier mobility data presented here. Additionally, a new parameterization for scattering of holes by phonons is presented and included in the model.
Feldmann Frank, Bivour Martin, Reichel Christian, Steinkemper Heiko, Hermle Martin, Glunz Stefan
Tunnel oxide passivated contacts as an alternative to partial rear contacts
2014 Solar Energy Materials and Solar Cells, Band: 131, Seiten: 46 - 50
P. Dennler, R. Quay, P. Brückner, M. Schlechtweg, O. Ambacher
Watt-level non-uniform distributed 6–37 GHz power amplifier MMIC with dual-gate driver stage in GaN technology
2014 IEEE Topical Conference on Power Amplifiers for Wireless and Radio Applications (PAWR), Seiten: 37 - 39
W Freude, S Koenig, D Lopez-Diaz, J Antes, F Boes, R Henneberger, A. Leuther, A. Tessmann, R. Schmogrow, D. Hillerkuss, R. Palmer, T. Zwick, C. Koos, O. Ambacher, J. Leuthold, I Kallfass
Wireless communications on THz carriers takes shape
2014 16th International Conference on Transparent Optical Networks (ICTON), Seiten: 1 - 4
S. Koenig, D. Lopez-Diaz, J. Antes, F. Boes, R. Henneberger, A. Leuther, A. Tessmann, R. Schmogrow, D. Hillerkuss, R. Palmer, T. Zwick, C. Koos, W. Freude, O. Ambacher, J. Leuthold, I. Kallfass
Wireless sub-THz communication system with high data rate enabled by RF photonics and active MMIC technology
2014 IEEE Photonics Conference, Seiten: 414 - 415
Kamp M, Bartsch J, Cimiotti G, Keding R, Zogaj A, Reichel C, Kalio A, Glatthaar M, Glunz Stefan
Zincate processes for silicon solar cell metallization
2014 Solar Energy Materials and Solar Cells, Band: 120, Seiten: 332 - 338

2013

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S. Maroldt, R. Quay, P. Dennler, D. Schwantuschke, M. Musser, M. Dammann, R. Aidam, P. Waltereit, A. Tessmann, O. Ambacher
(In) AlGaN Heterojunction Field Effect Transistors and Circuits for High-Power Applications at Microwave and Millimeter-Wave Frequencies
2013 Jpn J Appl Phys, Band: 52, Nummer: 8S, Seite: 08JN13
S. Koenig, F. Boes, D. Lopez-Diaz, J. Antes, R. Henneberger, R. Schmogrow, D. Hillerkuss, R. Palmer, T. Zwick, C. Koos, W. Freude, O. Ambacher, I. Kallfass, J. Leuthold
100 Gbit/s wireless link with mm-wave photonics
2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference (OFC/NFOEC), Seiten: 1 - 3
A. Leuther, A. Tessmann, M. Dammann, H. Massler, M. Schlechtweg, O. Ambacher
35 nm mHEMT technology for THz and ultra low noise applications
2013 International Conference on Indium Phosphide and Related Materials (IPRM), Seiten: 1 - 2
D. Lopez-Diaz, A. Tessmann, A. Leuther, S. Wagner, M. Schlechtweg, O. Ambacher, S. Koenig, J. Antes, F. Boes, F. Kurz, R. Henneberger, I. Kallfass
A 240 GHz quadrature receiver and transmitter for data transmission up to 40 Gbit/s
2013 European Microwave Integrated Circuit Conference, Seiten: 440 - 443
V. Hurm, R. Weber, A. Tessmann, H. Massler, A. Leuther, M. Kuri, M. Riessle, H. P. Stulz, M. Zink, M. Schlechtweg, O. Ambacher, T. Närhi
A 243 GHz LNA module based on mHEMT MMICs with integrated waveguide transitions
2013 IEEE microwave and wireless components letters, Band: 23, Nummer: 9, Seiten: 486 - 488
A. Tessmann, V. Hurm, A. Leuther, H. Massler, R. Weber, M. Kuri, M. Riessle, H.P. Stulz, M. Zink, M. Schlechtweg, O. Ambacher, T. Närhi
A 243 GHz low-noise amplifier module for use in next-generation direct detection radiometers
2013 European Microwave Integrated Circuit Conference, Seiten: 220 - 223
Weber Rainer, Schwantuschke Dirk, Brückner Peter, Quay Rüdiger, Mikulla Micheal, Ambacher Oliver, Kallfass Ingmar
A 67 GHz GaN voltage-controlled oscillator MMIC with high output power
2013 IEEE, Band: 23, Nummer: 7, Seiten: 374 - 376
C. Zech, A. Hülsmann, R. Weber, A. Tessmann, S. Wagner, M. Schlechtweg, A. Leuther, O. Ambacher
A compact 94 GHz FMCW radar MMIC based on 100 nm InGaAs mHEMT technology with integrated transmission signal conditioning
2013 European Microwave Integrated Circuit Conference, Seiten: 436 - 439
C. Zech, A. Hülsmann, M. Schlechtweg, L. Georgi, H. Gulan, O. Ambacher
A compact, universal and cost-efficient antenna setup for mmW-radar applications
2013 International Conference on Radar, Seiten: 417 - 421
D. Schwantuschke, M, Seelmann-Eggebert, P. Brückner, R. Quay, M. Mikulla, O. Ambacher, I. Kallfass
A fully scalable compact small-signal modeling approach for 100 nm AlGaN/GaN HEMTs
2013 European Microwave Integrated Circuit Conference, Seiten: 284 - 287
A. Tessmann, A. Leuther, H. Massler, U. Lewark, S. Wagner, R. Weber, M. Kuri, M. Zink, M. Riessle, H.-P. Stulz, M. Schlechtweg, O. Ambacher, R. Sommer, A. Wahlen, S. Stanko
A monolithic integrated mHEMT chipset for high-resolution submillimeter-wave radar applications
2013 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
B. Albrecht, S. Kopta, O. John, L. Kirste, R. Driad, K. Köhler, M. Walther, O. Ambacher
AlGaN ultraviolet A and ultraviolet C photodetectors with very high specific detectivity D
2013 Jpn J Appl Phys, Band: 52, Nummer: 8S, Seite: 08JB28
Rauer M, Schmiga C, Glatthaar M, Glunz Stefan
Alloying from screen-printed aluminum pastes containing boron additives
2013 IEEE Journal of Photovoltaics, Band: 3, Nummer: 1, Seiten: 206 - 211
S. Heinz, F. Balle, G. Wagner, D. Eifler
Analysis of fatigue properties and failure mechanisms of Ti6Al4V in the very high cycle fatigue regime using ultrasonic technology and 3D laser scanning vibrometry
2013 Ultrasonics, Band: 53, Nummer: 8, Seiten: 1433 - 1440
R. Reiner, P. Waltereit, F. Benkhelifa, S. Muller, M. Wespel, R. Quay, M. Schlechtweg, M. Mikulla, O. Ambacher
Benchmarking of large-area GaN-on-Si HFET power devices for highly-efficient, fast-switching converter applications
2013 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
M. Szymkiewicz, A. Hülsmann, A. Tessmann, M. Schlechtweg, A. Leuther, O. Ambacher, S. Koch, M. Riedel, I. Kallfass
Broadband absorption and emission millimeter-wave spectroscopy between 220 and 325 GHz
2013 Next-Generation Spectroscopic Technologies VI, Band: 8726
S. Linkohr, W. Pletschen, S. U. Schwarz, J. Anzt, V. Cimalla, O. Ambacher
CIP (cleaning-in-place) stability of AlGaN/GaN pH sensors
2013 J Biotechnol, Band: 163, Nummer: 4, Seiten: 354 - 361
R. E. Sah, C. Tegenkamp, M. Baeumler, F. Bernhardt, R. Driad, M. Mikulla, O. Ambacher
Characterization of Al2O3/GaAs interfaces and thin films prepared by atomic layer deposition
2013 Journal of Vacuum Science & Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena, Band: 31, Nummer: 4, Seite: 04D111
B. Baldischweiler, D. Bruch, I. Kallfass, M. Seelmann-Eggebert, A. Leuther, D. Peschel, M. Schlechtweg, O. Ambacher
Characterization of a DC to 40 GHz SPDT switch based on GaAs mHEMT technology at cryogenic temperature
2013 European Microwave Integrated Circuit Conference, Seiten: 141 - 144
V. Carrubba, S. Maroldt, R. Quay, O. Ambacher
Class-BJ power amplifier modes: The IMD behavior of reactive terminations
2013 European Microwave Integrated Circuit Conference, Seiten: 420 - 423
F. Thome, H. Massler, S. Wagner, A. Leuther, I. Kallfass, M. Schlechtweg, O. Ambacher
Comparison of two W-band low-noise amplifier MMICs with ultra low power consumption based on 50nm InGaAs mHEMT technology
2013 IEEE MTT-S International Microwave Symposium Digest (MTT), Seiten: 1 - 4
N. Heidrich, F. Knöbber, V. Polyakov, V. Cimalla, W. Pletschen, R. E. Sah, L. Kirste, S. Leopold, S. Hampl, O. Ambacher, V. Lebedev
Corrugated piezoelectric membranes for energy harvesting from aperiodic vibrations
2013 Sensors and Actuators A: Physical, Band: 195, Seiten: 32 - 37
R.E. Sah, L. Kirste, H. Kirmse, M. Mildner, L. Wilde, S. Kopta, F. Knöbber, M. Krieg, V. Cimalla, V. Lebedev, O. Ambacher
Crystallographic Texture of Submicron Thin Aluminum Nitride Films on Molybdenum Electrode for Suspended Micro and Nanosystems
2013 ECS Journal of Solid State Science and Technology, Band: 2, Nummer: 4, Seiten: 180 - 184
Giesecke J, Glunz Stefan, Warta W
Determination of actual carrier lifetime from differential measurements
2013 Energy Procedia, Band: 38, Nummer: 0, Seiten: 59 - 65
J. Binder, K. P. Korona, A. Wysmolek, M. Kaminska, K. Köhler, L. Kirste, O. Ambacher, M. Zajak, R. Dwilinski
Dynamics of thermalization in GaInN/GaN quantum wells grown on ammonothermal GaN
2013 J Appl Phys, Band: 114, Nummer: 22, Seite: 223504
Heidrich N, Iankov D, Hees J, Pletschen W, Sah RE, Kirste L, Zuerbig V, Nebel C, Ambacher O, Lebedev V
Enhanced mechanical performance of AlN/nanodiamond micro-resonators
2013 IOP Publishing, Band: 23, Nummer: 12, Seite: 125017
Müller R, Benick J, Bateman N, Schön J, Reichel C, Richter A, Hermle M, Glunz Stefan
Evaluation of implantation annealing for highly-doped selective boron emitters suitable for screen-printed contacts
2013 Solar Energy Materials and Solar Cells
Michl B, Benick J, Richter A, Bivour M, Yong J, Steeman R, Schubert M, Glunz Stefan
Excellent average diffusion lengths of 600 \textgreekmm of N-Type multicrystalline silicon wafers after the full solar cell process including boron diffusion
2013 Energy Procedia, Band: 33, Seiten: 41 - 49
S. Schmeer, F. Balle, M. Didi, S. Huxhold, G. Wagner, P. Mitschang, M. Maier
Experimental and Computational Analysis of Multi‐Spot Welded Hybrid Al/CFRP‐Structures on Component Level
2013 Adv Eng Mater, Band: 15, Nummer: 9, Seiten: 868 - 873
S. Schmeer, F. Balle, M. Didi, G. Wagner, M. Maier, P. Mitschang
Experimental and Numerical Characterization of Spot Welded Hybrid Al/CFRP‐Joints on Coupon Level
2013 Adv Eng Mater, Band: 15, Nummer: 9, Seiten: 853 - 860
Reusch M, Bivour M, Hermle M, Glunz Stefan
Fill factor limitation of silicon heterojunction solar cells by junction recombination
2013 Energy Procedia, Band: 38, Nummer: 0, Seiten: 297 - 304
P. Waltereit, W. Bronner, R. Quay, M. Dammann, M. Cäsar, S. Müller, R. Reiner, P. Brueckner, R. Kiefer, F. van Raay, J. Kühn, M. Musser, C. Haupt, M. Mikulla, O. Ambacher
GaN HEMTs and MMICs for space applications
2013 Semicond Sci Tech, Band: 28, Nummer: 7, Seite: 074010
H. Hahn, F. Benkhelifa, O. Ambacher, A. Alam, M. Heuken, H. Yacoub, A. Noculak, H. Kalisch, A. Vescan
GaN-on-Si enhancement mode metal insulator semiconductor heterostructure field effect transistor with on-current of 1.35 A/mm
2013 Jpn J Appl Phys, Band: 52, Nummer: 9R, Seite: 090204
P. Waltereit, R. Reiner, H. Czap, D. Peschel, S. Müller, R. Quay, M. Mikulla, O. Ambacher
GaN‐based high voltage transistors for efficient power switching
2013 physica status solidi c, Band: 10, Nummer: 5, Seiten: 831 - 834
Weidlich A, Renelt S, Schmidt P, Sobótka M, Storace S
Gesellschaftliche Akzeptanz von Smart Metering: Nicht ohne meine Kunden
2013 Energiewirtschaftliche Tagesfragen, Band: 63, Seiten: 93 - 96
J. Chéron, M. Campovecchio, R. Quéré, D. Schwantuschke, R. Quay, Oliver Ambacher
High-efficiency power amplifier MMICs in 100 nm GaN technology at Ka-band frequencies
2013 European Microwave Integrated Circuit Conference, Seiten: 292 - 295
D. Schwantuschke, P. Brueckner, R. Quay, M. Mikulla, O. Ambacher
High-gain millimeter-wave AlGaN/GaN transistors
2013 IEEE T Electron Dev, Band: 60, Nummer: 10, Seiten: 3112 - 3118
M. Mikulla, A. Leuther, P. Brückner, D. Schwantuschke, A. Tessmann, M. Schlechtweg, O. Ambacher, M. Caris
High-speed technologies based on III-V compound semiconductors at Fraunhofer IAF
2013 European Microwave Integrated Circuit Conference, Seiten: 169 - 171
F. Balle, S. Emrich, G. Wagner, D. Eifler, A. Brodyanski, M. Kopnarski
Improvement of Ultrasonically Welded Aluminum/Carbon Fiber Reinforced Polymer‐Joints by Surface Technology and High Resolution Analysis
2013 Adv Eng Mater, Band: 15, Nummer: 9, Seiten: 814 - 820
Rauer M, Rüdiger M, Schmiga C, Strutzberg H, Bähr M, Glatthaar M, Glunz S
Incomplete ionization of aluminum in silicon and its effect on accurate determination of doping profiles
2013 Journal of Applied Physics, Band: 114, Nummer: 20
M. Mußer, F. van Raay, P. Brückner, W. Bronner, R. Quay, M. Mikulla, O. Ambacher
Individual source vias for GaN HEMT power bars
2013 European Microwave Integrated Circuit Conference, Seiten: 184 - 187
F. Balle, S. Huxhold, S. Emrich, G. Wagner, M. Kopnarski, D. Eifler
Influence of Heat Treatments on the Mechanical Properties of Ultrasonic Welded AA 2024/CF‐PA66‐Joints
2013 Adv Eng Mater, Band: 15, Nummer: 9, Seiten: 837 - 845
Kraft A, Ni L, Kalio A, Moldovan A, Bartsch J, Glatthaar M, Glunz Stefan
Influence of the chemicals used in nickel and copper plating solutions on the adhesion of screen-printed silver contacts
2013 Energy Procedia, Band: 38, Nummer: 0, Seiten: 753 - 759
F. van Raay, R. Quay, M. Seelmann-Eggebert, D. Schwantuschke, T. Maier, M. Schlechtweg, O. Ambacher
Integral transform and state modeling of 0.1 µm AlGaN/GaN HEMTs for pulsed-RF and CW operation
2013 European Microwave Integrated Circuit Conference, Seiten: 288 - 291
Hiermaier S
Integrated experimental-numerical characterization of geological materials under shock and impact
2013 , Seiten: 71 - 76
KurzfassungScientific investigation of transient processes and engineering design of structures for dynamic loading conditions are still a great challenge. Other than quasi-static loading conditions a dynamic application of loads by impact or blast leads to additional effects that enhance the complexity of the thermo-mechanical material behavior. They can be reduced to two basic phenomena: first, the strain rate dependent change of mechanical behavior and, secondly, the evolution and propagation of shock waves. In order to understand the structural behavior under transient loading conditions, the involved materials need to be characterized by material tests. Mathematical formulations are needed for the description of both the strain rate dependent deviatoric behavior and the non-linear Equation of State responsible for the shock wave formation. Implemented into numerical codes these constitutive equations allow for a predictive simulation of the structural behavior. Sometimes nume rical simulation itself can be used to derive material properties. This is the case when for example the material is composed of two or more constituents for which the individual thermo-mechanical properties are known. Modeling the composite material as specimens and application of loads that may be outside the load types applicable in experiments leads to additional results not achievable in a pure experimental approach. Therefore, an integrated experimental-numerical approach for the characterization of materials under transient loading conditions is more and more preferred if predictive capabilities are needed for the highly complex phenomena observed in the related structural applications of interest.
Rauer M, Schmiga C, Tuschinsky A, Glatthaar M, Glunz S
Investigation of aluminum-boron doping profiles formed by coalloying from screen-printed pastes
2013 Energy Procedia, Band: 43, Seiten: 93 - 99
Reiterer, A., Baulig, C., Maindorfer, I. Wölfelschneider, H.
Lichtraumerfassung mit Hilfe neuester Lasermesstechnik
2013 Eisenbahningenieur, Band: Nr. 6, Seiten: 46 - 49
S. Leopold, T. Polster, D. Paetz, F. Knoebber, O. Ambacher, S. Sinzinger, M. Hoffmann
MOEMS tunable microlens made of aluminum nitride membranes
2013 Journal of Micro/Nanolithography, MEMS, and MOEMS, Band: 12, Nummer: 2, Seite: 023012
R. E. Sah, R. Driad, F. Bernhardt, L. Kirste, C.-C. Leancu, H. Czap, F. Benkhelifa, M. Mikulla, O. Ambacher
Mechanical and electrical properties of plasma and thermal atomic layer deposited Al2O3 films on GaAs and Si
2013 Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, Band: 31, Nummer: 4, Seite: 041502
Durr N, Sauer M, Güldemeister N, Wünnemann K, Hiermaier S
Mesoscale Investigation of Shock Wave Effects in Dry and Water-ĹĄaturated Sandstone
2013 Procedia Engineering, Band: 58, Seiten: 289 - 298
KurzfassungIn this paper, the behavior of natural sandstone under hypervelocity impact is investigated numerically. Sandstone essentially consists of cemented quartz grains, it can be generally considered as a polygranular structure with air or water-filled pores. In order to study the influence of pores and water filling on the behavior of sandstone under shock loading, a numerical investigation at the mesoscale is performed. We explicitly resolve pores and the closure of pores in a homogeneous and isotropic quartz matrix. The quartz matrix is described with an equation of state and a strength model; the pore geometry is simplified. Two-dimensional planar shock simulations are conducted in order to analyze effects of quartz strength and water-saturation on pore crushing. Averaging is used to perform a macroscale analysis of the dependencies of pressure and shock velocity on particle velocity. The simulation results shall enhance the basis for the development of accurate macroscale sandstone models that take the water content into account.
Mondon A, Jawaid M, Bartsch J, Glatthaar M, Glunz Stefan
Microstructure analysis of the interface situation and adhesion of thermally formed nickel silicide for plated nickel–copper contacts on silicon solar cells
2013 Solar Energy Materials and Solar Cells, Band: 117, Seiten: 209 - 213
M. Schlechtweg, A. Tessmann, A. Leuther, H. Massler, S. Wagner, R. Aidam, J. Rosenzweig, O. Ambacher, I. Kallfass, U. J. Lewark, R. Sommer, A. Wahlen, S. Stanko, J. Ender
Millimeter-and submillimeter-wave monolithic integrated circuits based on metamorphic HEMT technology for sensors and communication
2013 IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems (COMCAS), Seiten: 1 - 4
M. Klenner, C. Zech, A. Hülsmann, A. Tessmann, A. Leuther, M. Schlechtweg, J. Wagner, O. Ambacher
Multilayer material analysis using an active millimeter wave imaging system
2013 14th International Radar Symposium (IRS), Seiten: 207 - 213
N. Heidrich, J. Hees, V. Zuerbig, D. Iankov, W. Pletschen, R.E. Sah, B. Raynor, L. Kirste, C.E. Nebel, O. Ambacher, V. Lebedev
Nano-diamond vacuum MEMS for RF applications
2013 Transducers & Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS & EUROSENSORS XXVII), Seiten: 218 - 221
F. van Raay, R. Quay, M. Seelmann-Eggebert, D. Schwantuschke, D. Peschel, M. Schlechtweg, O. Ambacher
New Low-Frequency Dispersion Model for AlGaN/GaN HEMTs Using Integral Transform and State Description
2013 IEEE T Microw Theory, Band: 61, Nummer: 1, Seiten: 154 - 167
Rauer M, Mondon A, Schmiga C, Bartsch J, Glatthaar M, Glunz Stefan
Nickel-plated front contacts for front and rear emitter silicon solar cells
2013 Energy Procedia, Band: 38, Nummer: 0, Seiten: 449 - 458
P. Dennler, R. Quay, O. Ambacher
Novel semi-reactively-matched multistage broadband power amplifier architecture for monolithic ICs in GaN technology
2013 IEEE MTT-S International Microwave Symposium Digest (MTT), Seiten: 1 - 4
N. Konchakova, F. Balle, R. Müller, P. Steinmann, D. Eifler, F.J. Barth
Numerical Analysis of the Mechanical Behavior of Lightweight Metal‐CFRP Joints
2013 Adv Eng Mater, Band: 15, Nummer: 9, Seiten: 846 - 852
V. Zuerbig, D. Paetz, W. Pletschen, J. Hees, R.E. Sah, L. Kirste, N. Heidrich, V. Cimalla, C. Nebel, O. Ambacher, V. Lebedev
Piezo-actuated tunable diamond/AlN micro lenses
2013 Transducers & Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS & EUROSENSORS XXVII), Seiten: 2317 - 2320
J. Hees, N. Heidrich, W. Pletschen, R.E. Sah, M. Wolfer, O. Aneurin Williams, V. Lebedev, C.E. Nebel, O. Ambacher
Piezoelectric actuated micro-resonators based on the growth of diamond on aluminum nitride thin films
2013 Nanotechnology, Band: 24, Nummer: 2, Seite: 025601
N. Heidrich, V. Zuerbig, D. Iankov, W. Pletschen, R.E. Sah, B. Raynor, L. Kirste, C.E. Nebel, O. Ambacher, V. Lebedev
Piezoelectrically actuated diamond cantilevers for high-frequency applications
2013 Diamond and related materials, Band: 38, Seiten: 69 - 72
Roost J, Wendt G, Weidlich A
Preissensitivität und Kundenbindung im Strommarkt: Auf den Vertriebskanal kommt es an
2013 Energiewirtschaftliche Tagesfragen, Band: 63, Nummer: 10, Seiten: 8 - 12
Güldemeister N, Wünnemann K, Durr N, Hiermaier S
Propagation of impact-induced shock waves in porous sandstone using mesoscale modeling
2013 Meteoritics & planetary science, Band: 48, Nummer: 1, Seiten: 115 - 133
KurzfassungGeneration and propagation of shock waves by meteorite impact is significantly affected by material properties such as porosity, water content, and strength. The objective of this work was to quantify processes related to the shock-induced compaction of pore space by numerical modeling, and compare the results with data obtained in the framework of the Multidisciplinary Experimental and Modeling Impact Research Network (MEMIN) impact experiments. We use mesoscale models resolving the collapse of individual pores to validate macroscopic (homogenized) approaches describing the bulk behavior of porous and water-saturated materials in large-scale models of crater formation, and to quantify localized shock amplification as a result of pore space crushing. We carried out a suite of numerical models of planar shock wave propagation through a well-defined area (the âsampleâ) of porous and/or water-saturated material. The porous sample is either represented by a homogeneous unit where porosity is treated as a state variable (macroscale model) and water content by an equation of state for mixed material (ANEOS) or by a defined number of individually resolved pores (mesoscale model). We varied porosity and water content and measured thermodynamic parameters such as shock wave velocity and particle velocity on meso- and macroscales in separate simulations. The mesoscale models provide additional data on the heterogeneous distribution of peak shock pressures as a consequence of the complex superposition of reflecting rarefaction waves and shock waves originating from the crushing of pores. We quantify the bulk effect of porosity, the reduction in shock pressure, in terms of Hugoniot data as a function of porosity, water content, and strength of a quartzite matrix. We find a good agreement between meso-, macroscale models and Hugoniot data from shock experiments. We also propose a combination of a porosity compaction model (?â? model) that was previously only used for porous materials and the ANEOS for water-saturated quartzite (all pore space is filled with water) to describe the behavior of partially water-saturated material during shock compression. Localized amplification of shock pressures results from pore collapse and can reach as much as four times the average shock pressure in the porous sample. This may explain the often observed localized high shock pressure phases next to more or less unshocked grains in impactites and meteorites.
Gueldemeister, N., Wuennemann, K., Durr, N., Hiermaier, S.
Propagation of impact-induced shock waves in porous sandstone using mesoscale modeling
2013 Meteoritics & planetary science, Band: 48
KurzfassungGeneration and propagation of shock waves by meteorite impact is significantly affected by material properties such as porosity, water content, and strength. The objective of this work was to quantify processes related to the shock-induced compaction of pore space by numerical modeling, and compare the results with data obtained in the framework of the Multidisciplinary Experimental and Modeling Impact Research Network (MEMIN) impact experiments. We use mesoscale models resolving the collapse of individual pores to validate macroscopic (homogenized) approaches describing the bulk behavior of porous and water-saturated materials in large-scale models of crater formation, and to quantify localized shock amplification as a result of pore space crushing. We carried out a suite of numerical models of planar shock wave propagation through a well-defined area (the ""sample"") of porous and/or water-saturated material. The porous sample is either represented by a homogeneous unit where porosity is treated as a state variable (macroscale model) and water content by an equation of state for mixed material (ANEOS) or by a defined number of individually resolved pores (mesoscale model). We varied porosity and water content and measured thermodynamic parameters such as shock wave velocity and particle velocity on meso- and macroscales in separate simulations. The mesoscale models provide additional data on the heterogeneous distribution of peak shock pressures as a consequence of the complex superposition of reflecting rarefaction waves and shock waves originating from the crushing of pores. We quantify the bulk effect of porosity, the reduction in shock pressure, in terms of Hugoniot data as a function of porosity, water content, and strength of a quartzite matrix. We find a good agreement between meso-, macroscale models and Hugoniot data from shock experiments. We also propose a combination of a porosity compaction model (?-? model) that was previously only used for porous materials and the ANEOS for water-saturated quartzite (all pore space is filled with water) to describe the behavior of partially water-saturated material during shock compression. Localized amplification of shock pressures results from pore collapse and can reach as much as four times the average shock pressure in the porous sample. This may explain the often observed localized high shock pressure phases next to more or less unshocked grains in impactites and meteorites.
Richter A, Hermle M, Glunz S
Reassessment of the limiting efficiency for crystalline silicon solar cells
2013 IEEE Journal of Photovoltaics, Band: 3, Nummer: 4, Seiten: 1184 - 1191
P. Waltereit, W. Bronner, P. Brueckner, M. Dammann, R. Reiner, S. Mueller, J. Kuehn, M. Mußer, R. Quay, M. Mikulla, O. Ambacher
Recent development in GaN HEMTs and MMICs for high power electronics
2013 Japan Society of Applied Physics, Seiten: 958 - 959
M. Mischo, M. Bitterling, M. Himmerlich, S. Krischok, O. Ambacher, V. Cimalla
Seebeck ozone sensors
2013 Transducers & Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS & EUROSENSORS XXVII), Seiten: 1645 - 1648
F. Purkl, T. S. English, G. Yama, J. Provine, A. K. Samarao, A. Feyh, B. Kim, G. O'Brien, O. Ambacher, R. T. Howe, T. W. Kenny
Serpentine geometry for enhanced performance of nanometer-thin platinum bolometers
2013 Transducers & Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems, Seiten: 1507 - 1510
Reichel C, Granek F, Hermle M, Glunz S
Short-circuit current losses in back-contacted back-junction Si solar cells: Experiment and simulation of the charge collection probability
2013 IEEE Journal of Photovoltaics, Band: 3, Nummer: 1, Seiten: 217 - 223
U.J. Lewark, A. Tessmann, A. Leuther, T. Zwick, O. Ambacher, I. Kallfass
Signal generation and amplification up to 600 GHz using metamorphic HEMT technology
2013 European Microwave Integrated Circuit Conference, Seiten: 125 - 128
Löper P, Canino M, Qazzazie D, Schnabel M, Allegrezza M, Summonte C, Glunz Stefan, Janz S, Zacharias M
Silicon nanocrystals embedded in silicon carbide: Investigation of charge carrier transport and recombination
2013 Applied Physics Letters, Band: 102, Nummer: 3
N. Konchakova, R. Müller, P. Steinmann, F. Balle, D. Eifler, F.J. Barth
Simulation of Adhesive Joints by Viscoelastic Interface Material Model
2013 Adv Eng Mater, Band: 15, Nummer: 9, Seiten: 861 - 867
F. Purkl, T. English, G. Yama, J. Provine, A. K. Samarao, A. Feyh, G. O'Brien, O. Ambacher, R. T. Howe, T. W. Kenny
Sub-10 nanometer uncooled platinum bolometers via plasma enhanced atomic layer deposition
2013 IEEE 26th International Conference on Micro Electro Mechanical Systems (MEMS), Seiten: 185 - 188
R. Quay, P. Waltereit, J. Kühn, P. Brückner, M. van Heijningen, P. Jukkala, K. Hirche, O. Ambacher
Submicron-AlGaN/GaN MMICs for space applications
2013 IEEE MTT-S International Microwave Symposium Digest (MTT), Seiten: 1 - 4
A. Tessmann, M. Schlechtweg, D. Bruch, U. J Lewark, A. Leuther, H. Massler, S. Wagner, M. Seelmann-Eggebert, V. Hurm, R. Aidam, I. Kallfass, O. Ambacher
Terahertz monolithic integrated circuits based on metamorphic HEMT technology for sensors and communication
2013 Asia-Pacific Microwave Conference Proceedings (APMC), Seiten: 203 - 205
S. U. Schwarz, V. Cimalla, G. Eichapfel, M. Himmerlich, S. Krischok, O. Ambacher
Thermal functionalization of GaN surfaces with 1-alkenes
2013 Langmuir, Band: 29, Nummer: 21, Seiten: 6296 - 6301
J. Antes, S. Koenig, D. Lopez-Diaz, F. Boes, A. Tessmann, R. Henneberger, O. Ambacher, T. Zwick, I. Kallfass
Transmission of an 8-PSK modulated 30 Gbit/s signal using an MMIC-based 240 GHz wireless link
2013 IEEE MTT-S International Microwave Symposium Digest (MTT), Seiten: 1 - 3
N. Heidrich, V. Zürbig, D. Iankov, W. Pletschen, R. E. Sah, B. Raynor, L. Kirste, C. E. Nebel, O. Ambacher, V. Lebedev
Transparent diamond electrodes for tunable micro-optical devices
2013 Diamond and related materials, Band: 38, Seiten: 101 - 103
S. Leopold, D. Paetz, F. Knoebber, O. Ambacher, S. Sinzinger, M. Hoffmann
Tunable cylindrical microlenses based on aluminum nitride membranes
2013 MOEMS and Miniaturized Systems XII, Band: 8616, Seite: 861611
M. De Luca, G. Pettinari, A. Polimeni, M. Capizzi, G. Ciatto, L. Amidani, E. Fonda, F. Boscherini, F. Filippone, A. Amore Bonapasta, A. Knübel, V. Cimalla, O. Ambacher, D. Giubertoni, M. Bersani
Tuning of the optical properties of In-rich Inx InxGa1−xN (x=0.82−0.49) alloys by light-ion irradiation at low energy
2013 AIP Conference Proceedings, Band: 1566, Nummer: 1, Seiten: 93 - 94
G. Wagner, F. Balle, D. Eifler
Ultrasonic welding of aluminum alloys to fiber reinforced polymers
2013 Adv Eng Mater, Band: 15, Nummer: 9, Seiten: 792 - 803
Giesecke J, Glunz Stefan, Warta W
Understanding and resolving the discrepancy between differential and actual minority carrier lifetime
2013 Journal of Applied Physics, Band: 113, Nummer: 7
E. Weissbrodt, M. Schlechtweg, O. Ambacher, I. Kallfass
W-band active loads and switching front-end MMICs for radiometer calibration
2013 International Journal of Microwave and Wireless Technologie, Band: 5, Nummer: 3, Seiten: 293 - 299
F. Balle, D. Eifler
Welded Metal/CFRP‐Structures
2013 Adv Eng Mater, Band: 15, Nummer: 9, Seiten: 791 - 791
S. Koenig, D. Lopez-Diaz, J. Antes, F. Boes, R. Henneberger, A. Leuther, A. Tessmann, R. Schmogrow, D. Hillerkuss, R. Palmer, T. Zwick, C. Koos, W. Freude, O. Ambacher, J. Leuthold, I. Kallfass
Wireless sub-THz communication system with high data rate
2013 Nat Photonics, Band: 7, Nummer: 12, Seite: 977

2012

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J. Antes, S. Koenig, A. Leuther, H. Massler, J. Leuthold, O. Ambacher, I. Kallfass
220 GHz wireless data transmission experiments up to 30 Gbit/s
2012 IEEE/MTT-S International Microwave Symposium Digest, Seiten: 1 - 3
May M, Kilchert S, Hiermaier S
3D modeling of fracture in brittle isotropic materials using a novel algorithm for the determination of the fracture plane orientation and crack surface area
2012 Finite Elements in Analysis and Design, Band: 56, Seiten: 32 - 40
KurzfassungA user defined material model for simulation of brittle fracture in isotropic materials was implemented into the explicit FE code Abaqus/Explicit. The model uses a methodology for calculating the orientation of the fracture plane in isotropic materials in 3D space using an analytical approach. Knowing the orientation of the fracture plane, the cross-sectional area of the fracture surface can in a hexagonal element can be calculated. Regularization is then achieved using the size of the fracture plane. The model is first tested on single-element tests and then applied to more complex test cases such as a short bar with chevron notch or micromechanical analyses of composite materials. The numerical predictions correlate well with experimental evidence from the literature.
May, M., Kilchert, S., Hiermaier, S.
3D modeling of fracture in brittle isotropic materials using a novel algorithm for the determination of the fracture plane orientation and crack surface area
2012 Finite Elements in Analysis and Design, Band: 56, Seiten: 32 - 40
KurzfassungA user defined material model for simulation of brittle fracture in isotropic materials was implemented into the explicit FE code Abaqus/Explicit. The model uses a methodology for calculating the orientation of the fracture plane in isotropic materials in 3D space using an analytical approach. Knowing the orientation of the fracture plane, the cross-sectional area of the fracture surface can in a hexagonal element can be calculated. Regularization is then achieved using the size of the fracture plane. The model is first tested on single-element tests and then applied to more complex test cases such as a short bar with chevron notch or micromechanical analyses of composite materials. The numerical predictions correlate well with experimental evidence from the literature.
A. Leuther, A. Tessmann, H. Massler, R. Aidam, M. Schlechtweg, O. Ambacher
450 GHz amplifier MMIC in 50 nm metamorphic HEMT technology
2012 International Conference on Indium Phosphide and Related Materials, Seiten: 229 - 232
P. Dennler, D. Schwantuschke, R. Quay, O. Ambacher
8–42 GHz GaN non-uniform distributed power amplifier MMICs in microstrip technology
2012 IEEE/MTT-S International Microwave Symposium Digest, Seiten: 1 - 3
S. Ayhan, S. Diebold, S. Scherr, A. Tessmann, O. Ambacher, I. Kallfass, T. Zwick
A 96 GHz radar system for respiration and heart rate measurements
2012 IEEE/MTT-S International Microwave Symposium Digest, Seiten: 1 - 3
D. Schwantuschke, P. Brückner, R. Quay, M. Mikulla, O. Ambacher, I. Kallfass
A U-band broadband power amplifier MMIC in 100 nm AlGaN/GaN HEMT technology
2012 7th European Microwave Integrated Circuit Conference, Seiten: 703 - 706
S. Diebold, S. Ayhan, S. Scherr, H. Massler, A. Tessmann, A. Leuther, O. Ambacher, T. Zwick, I. Kallfass
A W-band MMIC radar system for remote detection of vital signs
2012 J Infrared Millim Te, Band: 33, Nummer: 12, Seiten: 1250 - 1267
Löper P, Stüwe D, Künle M, Bivour M, Reichel C, Neubauer R, Schnabel M, Hermle M, Eibl O, Janz S, Zacharias M, Glunz Stefan
A membrane device for substrate-free photovoltaic characterization of quantum dot based p-i-n solar cells
2012 Advanced Materials, Band: 24, Nummer: 23, Seiten: 3124 - 3129
D. Bruch, R.I. Amils, J.D. Gallego, M. Seelmann-Eggebert, B. Aja, F. Schafer, C. Diez, A. Leuther, M. Schlechtweg, O. Ambacher, I. Kallfass
A noise source module for in-situ noise figure measurements from DC to 50 GHz at cryogenic temperatures
2012 IEEE microwave and wireless components letters, Band: 22, Nummer: 12, Seiten: 657 - 659
D. Lopez-Diaz, I. Kallfass, A. Tessmann, A. Leuther, S. Wagner, M. Schlechtweg, O. Ambacher
A subharmonic chipset for gigabit communication around 240 GHz
2012 IEEE/MTT-S International Microwave Symposium Digest, Seiten: 1 - 3
F. Thome, S. Diebold, M. Schlechtweg, A. Leuther, O. Ambacher, I. Kallfass
A tunable 140GHz analog phase shifter with high linearity performance
2012 The 7th German Microwave Conference, Seiten: 1 - 4
E. Weissbrodt, A. Tessmann, M. Schlechtweg, I. Kallfass, O. Ambacher
Active load modules for W-band radiometer calibration
2012 IEEE International Geoscience and Remote Sensing Symposium, Seiten: 2945 - 2948
D. Krausse, F. Benkhelifa, R. Reiner, R. Quay, O. Ambacher
AlGaN/GaN power amplifiers for ISM applications
2012 Solid State Electron, Band: 74, Seiten: 108 - 113
S. Maroldt, P. Brueckner, R. Quay, O. Ambacher, S. Maier, D. Wiegner, A. Pascht
An integrated 12 Gbps switch-mode driver MMIC with 5 VPP for digital transmitters in 100 nm GaN technology
2012 7th European Microwave Integrated Circuit Conference, Seiten: 115 - 118
C. Zech, S. Diebold, S. Wagner, M. Schlechtweg, A. Leuther, O. Ambacher, I. Kallfass
An ultra-broadband low-noise traveling-wave amplifier based on 50nm InGaAs mHEMT technology
2012 The 7th German Microwave Conference, Seiten: 1 - 4
Wendling M, Mondon A, Kraft A, Bartscha J, Glatthaar M, Glunz Stefan
Analysis of Chemical Stability of Printing Pastes in Electrochemical Plating Solutions
2012 Energy Procedia, Band: 27, Seiten: 497 - 502
Löper P, Pysch D, Richter A, Hermle M, Janz S, Zacharias M, Glunz Stefan
Analysis of the temperature dependence of the open-circuit voltage
2012 Energy Procedia, Band: 27, Seiten: 135 - 142
Reichel C, Granek F, Hermle M, Glunz Stefan
Back-contacted back-junction n -type silicon solar cells featuring an insulating thin film for decoupling charge carrier collection and metallization geometry
2012 Progress in Photovoltaics: Research and Applications
D. Bruch, M. Seelmann-Eggebert, I. Kallfass, A. Leuther, S. Diebold, M. Schlechtweg, O. Ambacher
Broadband MMIC tuners dedicated to noise parameter measurements at cryogenic temperatures
2012 Workshop on Integrated Nonlinear Microwave and Millimetre-wave Circuits, Seiten: 1 - 3
Reichel C, Granek F, Benick J, Schultz-Wittmann O, Glunz Stefan
Comparison of emitter saturation current densities determined by injection-dependent lifetime spectroscopy in high and low injection regimes
2012 Progress in Photovoltaics: Research and Applications, Band: 20, Nummer: 1, Seiten: 21 - 30
Ganzenmueller Georg, Hiermaier Stefan, Steinhauser Martin
Consistent Temperature Coupling with Thermal Fluctuations of Smooth Particle Hydrodynamics and Molecular Dynamics
2012 1160 BATTERY STREET, STE 100, SAN FRANCISCO, CA 94111 USA PLOS ONE, PUBLIC LIBRARY SCIENCE, Band: 7, Nummer: 12
KurzfassungWe propose a thermodynamically consistent and energy-conserving temperature coupling scheme between the atomistic and the continuum domain. The coupling scheme links the two domains using the DPDE (Dissipative Particle Dynamics at constant Energy) thermostat and is designed to handle strong temperature gradients across the atomistic/continuum domain interface. The fundamentally different definitions of temperature in the continuum and atomistic domain - internal energy and heat capacity versus particle velocity - are accounted for in a straightforward and conceptually intuitive way by the DPDE thermostat. We verify the here-proposed scheme using a fluid, which is simultaneously represented as a continuum using Smooth Particle Hydrodynamics, and as an atomistically resolved liquid using Molecular Dynamics. In the case of equilibrium contact between both domains, we show that the correct microscopic equilibrium properties of the atomistic fluid are obtained. As an example of a strong non-equilibrium situation, we consider the propagation of a steady shock-wave from the continuum domain into the atomistic domain, and show that the coupling scheme conserves both energy and shock-wave dynamics. To demonstrate the applicability of our scheme to real systems, we consider shock loading of a phospholipid bilayer immersed in water in a multi-scale simulation, an interesting topic of biological relevance.
Ganzenmüller G, Hiermaier S, Steinhauser M
Consistent temperature coupling with thermal fluctuations of smooth particle hydrodynamics and molecular dynamics
2012 PLoS one. Online journal, Band: 7, Nummer: 12
KurzfassungWe propose a thermodynamically consistent and energy-conserving temperature coupling scheme between the atomistic and the continuum domain. The coupling scheme links the two domains using the DPDE (Dissipative Particle Dynamics at constant Energy) thermostat and is designed to handle strong temperature gradients across the atomistic/continuum domain interface. The fundamentally different definitions of temperature in the continuum and atomistic domain - internal energy and heat capacity versus particle velocity - are accounted for in a straightforward and conceptually intuitive way by the DPDE thermostat. We verify the here-proposed scheme using a fluid, which is simultaneously represented as a continuum using Smooth Particle Hydrodynamics, and as an atomistically resolved liquid using Molecular Dynamics. In the case of equilibrium contact between both domains, we show that the correct microscopic equilibrium properties of the atomistic fluid are obtained. As an example of a strong non-equilibrium situation, we consider the propagation of a steady shock-wave from the continuum domain into the atomistic domain, and show that the coupling scheme conserves both energy and shock-wave dynamics. To demonstrate the applicability of our scheme to real systems, we consider shock loading of a phospholipid bilayer immersed in water in a multi-scale simulation, an interesting topic of biological relevance.
Ganzenmueller, G.C., Hiermaier, S., Steinhauser, M.O.
Consistent temperature coupling with thermal fluctuations of smooth particle hydrodynamics and molecular dynamics
2012 PLoS one. Online journal, Band: 7, Seite: Art. e51989, 11
KurzfassungWe propose a thermodynamically consistent and energy-conserving temperature coupling scheme between the atomistic and the continuum domain. The coupling scheme links the two domains using the DPDE (Dissipative Particle Dynamics at constant Energy) thermostat and is designed to handle strong temperature gradients across the atomistic/continuum domain interface. The fundamentally different definitions of temperature in the continuum and atomistic domain - internal energy and heat capacity versus particle velocity - are accounted for in a straightforward and conceptually intuitive way by the DPDE thermostat. We verify the here-proposed scheme using a fluid, which is simultaneously represented as a continuum using Smooth Particle Hydrodynamics, and as an atomistically resolved liquid using Molecular Dynamics. In the case of equilibrium contact between both domains, we show that the correct microscopic equilibrium properties of the atomistic fluid are obtained. As an example of a strong non-equilibrium situation, we consider the propagation of a steady shock-wave from the continuum domain into the atomistic domain, and show that the coupling scheme conserves both energy and shock-wave dynamics. To demonstrate the applicability of our scheme to real systems, we consider shock loading of a phospholipid bilayer immersed in water in a multi-scale simulation, an interesting topic of biological relevance.
V. Carrubba, R. Quay, M. Schlechtweg, O. Ambacher, M. Akmal, J. Lees, J. Benedikt, P. J Tasker, S. C. Cripps
Continuous-ClassF3 power amplifier mode varying simultaneously first 3 harmonic impedances
2012 IEEE/MTT-S International Microwave Symposium Digest, Seiten: 1 - 3
Boljen M, Hiermaier S
Continuum constitutive modeling of woven fabrics
2012 European physical journal special topics, Band: 206, Nummer: 1, Seiten: 149 - 161
KurzfassungThe constitutive behavior of woven fabrics is significantly influenced by distinctive yarn interactions at the fabric mesoscale. Since, in most cases, an explicit discretization at yarn level is not desirable due to the related computational effort, an improved computational approach is proposed using a simple, but powerful kinematic model linked to the deformation of a representative volume cell (RVC) at the fabric mesoscale. The constitutive model is validated experimentally for three different fabric materials and implemented as user-defined subroutine in the explicit finite-element code LS-DYNA. The model includes an enhanced formulation for rate-dependent, dissipative shear properties.
Boljen, M., Hiermaier, S.
Continuum constitutive modeling of woven fabrics
2012 European physical journal special topics, Band: 206, Seiten: 149 - 161
KurzfassungThe constitutive behavior of woven fabrics is significantly influenced by distinctive yarn interactions at the fabric mesoscale. Since, in most cases, an explicit discretization at yarn level is not desirable due to the related computational effort, an improved computational approach is proposed using a simple, but powerful kinematic model linked to the deformation of a representative volume cell (RVC) at the fabric mesoscale. The constitutive model is validated experimentally for three different fabric materials and implemented as user-defined subroutine in the explicit finite-element code LS-DYNA. The model includes an enhanced formulation for rate-dependent, dissipative shear properties.
P. Brückner, R. Kiefer, C. Haupt, A. Leuther, S. Müller, R. Quay, D. Schwantuschke, M. Mikulla, O. Ambacher
Development of 100 nm gate AlGaN/GaN HEMT and MMIC technology suitable for mm‐wave applications
2012 physica status solidi c, Band: 9, Nummer: 3-4, Seiten: 903 - 906
V. Carrubba, S. Maroldt, M. Mußer, H. Walcher, M. Schlechtweg, R. Quay, O. Ambacher
Dual-band Class-ABJ AlGaN/GaN high power amplifier
2012 7th European Microwave Integrated Circuit Conference, Seiten: 635 - 638
Rüdiger M, Schmiga C, Rauer M, Hermle M, Glunz Stefan
Efficiency potential of n-type silicon solar cells with aluminum-doped rear p+ emitter
2012 IEEE Transactions on Electron Devices, Band: 59, Nummer: 5, Seiten: 1295 - 1303
V. Lebedev, N. Heidrich, F. Knöbber, R. E. Sah, W. Pletschen, B. Raynor, V. M. Polyakov, V. Cimalla, O. Ambacher
Electrostatically coupled vibration modes in unimorph complementary microcantilevers
2012 Appl Phys Lett, Band: 100, Nummer: 12, Seite: 124104
Ganzenmüller G, Hiermaier S, Steinhauser M
Energy-based coupling of smooth particle hydrodynamics and molecular dynamics with thermal fluctuations
2012 European physical journal special topics, Band: 206, Nummer: 1, Seiten: 51 - 60
KurzfassungWe propose a thermodynamically consistent and energy conserving coupling scheme between the atomistic and the continuum domain. The coupling scheme links the two domains using the DPDE (Dissipative Particle Dynamics at constant Energy) thermostat and is designed to handle strong temperature gradients across the atomistic/continuum domain interface. The fundamentally different definitions of temperature in the continuum and atomistic domain - internal energy and heat capacity versus particle velocity - are accounted for in a straightforward and conceptually intuitive way by the DPDE thermostat. We verify the here proposed scheme using a fluid, which is simultaneously represented as a continuum using Smooth Particle Hydrodynamics, and as an atomistically resolved liquid using Molecular Dynamics. In the case of equilibrium contact between both domains, we show that the correct microscopic equilibrium properties of the atomistic fluid are obtained. As an example of a strong non-equilibrium situation, we consider the propagation of a steady shock-wave from the continuum domain into the atomistic domain, and show that the coupling scheme conserves both energy and shock-wave dynamics.
Ganzenmueller G, Hiermaier S, Steinhauser M
Energy-based coupling of smooth particle hydrodynamics and molecular dynamics with thermal fluctuations
2012 TIERGARTENSTRASSE 17, D-69121 HEIDELBERG, GERMANY EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS, SPRINGER HEIDELBERG, Band: 206, Nummer: 1, Seiten: 51 - 60
KurzfassungWe propose a thermodynamically consistent and energy conserving coupling scheme between the atomistic and the continuum domain. The coupling scheme links the two domains using the DPDE (Dissipative Particle Dynamics at constant Energy) thermostat and is designed to handle strong temperature gradients across the atomistic/continuum domain interface. The fundamentally different definitions of temperature in the continuum and atomistic domain - internal energy and heat capacity versus particle velocity - are accounted for in a straightforward and conceptually intuitive way by the DPDE thermostat. We verify the here proposed scheme using a fluid, which is simultaneously represented as a continuum using Smooth Particle Hydrodynamics, and as an atomistically resolved liquid using Molecular Dynamics. In the case of equilibrium contact between both domains, we show that the correct microscopic equilibrium properties of the atomistic fluid are obtained. As an example of a strong non-equilibrium situation, we consider the propagation of a steady shock-wave from the continuum domain into the atomistic domain, and show that the coupling scheme conserves both energy and shock-wave dynamics.
Ganzenmueller, G.C., Hiermaier, S., Steinhauser, M.O.
Energy-based coupling of smooth particle hydrodynamics and molecular dynamics with thermal fluctuations
2012 European physical journal special topics, Band: 206, Seiten: 51 - 60
KurzfassungWe propose a thermodynamically consistent and energy conserving coupling scheme between the atomistic and the continuum domain. The coupling scheme links the two domains using the DPDE (Dissipative Particle Dynamics at constant Energy) thermostat and is designed to handle strong temperature gradients across the atomistic/continuum domain interface. The fundamentally different definitions of temperature in the continuum and atomistic domain - internal energy and heat capacity versus particle velocity - are accounted for in a straightforward and conceptually intuitive way by the DPDE thermostat. We verify the here proposed scheme using a fluid, which is simultaneously represented as a continuum using Smooth Particle Hydrodynamics, and as an atomistically resolved liquid using Molecular Dynamics. In the case of equilibrium contact between both domains, we show that the correct microscopic equilibrium properties of the atomistic fluid are obtained. As an example of a strong non-equilibrium situation, we consider the propagation of a steady shock-wave from the continuum domain into the atomistic domain, and show that the coupling scheme conserves both energy and shock-wave dynamics.
V. Lebedev, F. Knöbber, N. Heidrich, R. E. Sah, W. Pletschen, V. Cimalla, O. Ambacher
Evaluation of AlN material properties through vibration analysis of thin membranes
2012 physica status solidi c, Band: 9, Nummer: 2, Seiten: 403 - 406
S. Huxhold, F. Balle, G. Wagner, D. Eifler
Fatigue Behavior and Damage Monitoring of Ultrasonic Welded Hybrid Joints
2012 13th International Conference on Aluminum Alloys, Band: -, Seiten: 505 - 510
H. Hahn, B. Reuters, A. Wille, N. Ketteniss, F. Benkhelifa, O. Ambacher, H. Kalisch, A. Vescan
First polarization-engineered compressively strained AlInGaN barrier enhancement-mode MISHFET
2012 Semicond Sci Tech, Band: 27, Nummer: 5, Seite: 055004
R. Reiner, P. Waltereit, F. Benkhelifa, S. Müller, H. Walcher, S. Wagner, R. Quay, M. Schlechtweg, O. Ambacher
Fractal structures for low-resistance large area AlGaN/GaN power transistors
2012 24th International Symposium on Power Semiconductor Devices and ICs, Seiten: 341 - 344
V. Hurm, A. Tessmann, H. Massler, A. Leuther, M. Riessle, M. Zink, M. Schlechtweg,, O. Ambacher
GaAs microstrip-to-waveguide transition operating in the WR-1.5 waveguide band (500–750 GHz)
2012 Asia Pacific Microwave Conference Proceedings, Seiten: 145 - 147
D. Schwantuschke, I. Kallfass, R. Quay, O. Ambacher
GaN-based millimeter-wave monolithic integrated circuits
2012 19th International Conference on Microwaves, Radar & Wireless Communications, Band: 1, Seiten: 97 - 98
P. Waltereit, W. Bronner, R. Quay, M. Dammann, M. Cäsar, S. Müller, F. van Raay, R. Kiefer, P. Brückner, J. Kühn, M. Musser, L. Kirste, C. Haupt, W. Pletschen, T. Lim, R. Aidam, M. Mikulla, O. Ambacher
GaN‐based high‐frequency devices and circuits: A Fraunhofer perspective
2012 Phys Status Solidi A, Band: 209, Nummer: 3, Seiten: 491 - 496
M. Caesar, M. Dammann, V. Polyakov, P. Waltereit, W. Bronner, M. Baeumler, R. Quay, M. Mikulla, O. Ambacher
Generation of traps in AlGaN/GaN HEMTs during RF-and DC-stress test
2012 IEEE International Reliability Physics Symposium (IRPS)
R. Driad, R. Schmidt, L. Kirste, R. Loesch, M. Mikulla, O. Ambacher
Hafnium oxide passivation of InGaAs/InP heterostructure bipolar transistors by electron beam evaporation
2012 physica status solidi c, Band: 9, Nummer: 2, Seiten: 381 - 384
P. Waltereit, J. Kühn, R. Quay, F. Van Raay, M. Dammann, M. Cäsar, S. Müller, M. Mikulla, O. Ambacher, J. Lätti, M. Rostewitz, K. Hirche, J. Däubler
High efficiency X-band AlGaN/GaN MMICs for space applications with lifetimes above 10^5hours
2012 7th European Microwave Integrated Circuit Conference, Seiten: 123 - 126
E. Weissbrodt, A. Leuther, M. Schlechtweg, I. Kallfass, O. Ambacher
Highly integrated switching calibration front-end MMIC with active loads for w-band radiometers
2012 7th European Microwave Integrated Circuit Conference, Seiten: 203 - 206
Richter A, Werner F, Cuevas A, Schmidt J, Glunz Stefan
Improved parameterization of Auger recombination in silicon
2012 Energy Procedia, Band: 27, Seiten: 88 - 94
Richter A, Glunz Stefan, Werner F, Schmidt J, Cuevas A
Improved quantitative description of Auger recombination in crystalline silicon
2012 Physical Review B, Band: 86, Nummer: 16, Seiten: 1 - 14
Bivour M, Reichel C, Hermle M, Glunz Stefan
Improving the a-Si:H(p) rear emitter contact of n-type silicon solar cells: H(p) rear emitter contact of n-type silicon solar cells
2012 Solar Energy Materials and Solar Cells, Band: 106, Seiten: 11 - 16
P. Waltereit, W. Bronner, M. Musser, F. van Raay, M. Dammann, M. Cäsar, S. Müller, L. Kirste, K. Köhler, R. Quay, M. Mikulla, O. Ambacher
Influence of AlGaN barrier thickness on electrical and device properties in Al0.14Ga0.86N/GaN high electron mobility transistor structures
2012 J Appl Phys, Band: 112, Nummer: 5, Seite: 053718
S. Linkohr, W. Pletschen, V. Polyakov, M. Himmerlich, P. Lorenz, S. Krischok, L. Kirste, S. Müller, O. Ambacher, V. Cimalla
Influence of plasma treatments on the properties of GaN/AlGaN/GaN HEMT structures
2012 physica status solidi c, Band: 9, Nummer: 3-4, Seiten: 1096 - 1098
S. Heinz, F. Balle, G. Wagner, D. Eifler
Innovative Ultrasonic Testing Facility for Fatigue Experiments in the VHCF Regime
2012 Mater Test, Band: 54, Seiten: 750 - 755
D. Bruch, R.I. Amils, J.D. Gallego, M. Seelmann-Eggebert, B. Aja, F Schäfer, C. Diez, A. Leuther, M. Schlechtweg, O. Ambacher, I. Kallfass
Measurement Techniques, System Modeling Techniques, and Applications-A Noise Source Module for In-Situ Noise Figure Measurements From DC to 50 GHz at Cryogenic Temperatures
2012 IEEE Microwave and Wireless Components Letters, Band: 22, Nummer: 12, Seite: 657
F. Gütle, M. Baeumler, M. Dammann, M. Cäsar, H. Walcher, P. Waltereit, W. Bronner, S. Müller, R. Kiefer, R. Quay, M. Mikulla, O. Ambacher, A. Graff, F. Altmann, M. Simon
Microscopic degradation analysis of RF-stressed AlGaN/GaN HEMTs
2012 Materials Science Forum, Band: 725, Seiten: 79 - 82
M. Schlechtweg, A. Tessmann, A. Hülsmann, I. Kallfass, A. Leuther, R. Aidam, C. Zech, U. J. Lewark, H. Massler, M. Riessle, M. Zink, J. Rosenzweig, O. Ambacher
Millimeter-Wave Monolithic Integrated Circuits and Modules for Safety and Security Applications
2012 Future Security Research Conference, Seiten: 200 - 211
Reiterer, A.
Modeling Atmospheric Refraction Influences by Optical Turbulences Using an Image-Assisted Total Station
2012 Zeitschrift für Vermessungswesen (ZfV), Band: 3, Seiten: 156 - 165
Hiermaier S, Kilchert S, May M
Modellierung des Einflusses von UnregelmĂ¤Ăigkeiten in der Mikrostruktur auf das Versagen von UD-Composites
2012
Steinhauser M, GanzenmĂźller G, Hiermaier S
Multiscale modeling and simulation of shock-wave impact failure in hard and soft matter
2012 , Seiten: 803 - 808
KurzfassungUnderstanding the mechanisms of failure in materials on various length- and time scales is a prerequisite for the design of new materials with desired superior properties such as high toughness or strength. On the macroscopic scale, many materials such as concrete or ceramics may be viewed as being homogeneous; however, on the scale of a few microns these materials often exhibit an inhomogeneous polyhedral granular structure which is known to influence its macroscopic mechanical and optical properties, see e.g. Steinhauser [1].
U. Rabe, T. Helfen, M. Weikert, S. Hirsekorn, H.G. Herrmann, C. Boller, D. Backe, F. Balle, D. Eifler
Nonlinear ultrasonic testing of carbon fibre reinforced plastics in the very high cycle fatigue regime
2012 Proceedings of Meetings on Acoustics, Band: 16, Nummer: 1, Seiten: - - -
Rühle K, Rauer M, Rüdiger M, Giesecke J, Niewelt T, Schmiga C, Glunz Stefan, Kasemann M
Passivation layers for indoor solar cells at low irradiation intensities
2012 Energy Procedia, Band: 27, Seiten: 406 - 411
Ch. Y. Wang, S. Bagchi, M. Bitterling, R.W. Becker, K. Köhler, V. Cimalla, O. Ambacher, C. Chaumette
Photon stimulated ozone sensor based on indium oxide nanoparticles II: Ozone monitoring in humidity and water environments
2012 Sensors and Actuators B: Chemical, Band: 164, Nummer: 1, Seiten: 37 - 42
Löper P, Witzky A, Hartel A, Gutsch S, Hiller D, Goldschmidt J, Janz S, Glunz Stefan, Zacharias M, Freundlich A, Guillemoles J.-F.
Photovoltaic Properties of Silicon Nanocrystals in Silicon Carbide
2012 Proceedings of SPIE, Band: 8256, Seiten: 82560G - 82560G
S. Linkohr, W. Pletschen, L. Kirste, M. Himmerlich, P. Lorenz, S. Krischok, V. Polyakov, S. Müller, O. Ambacher, V. Cimalla
Plasma affected 2DEG properties on GaN/AlGaN/GaN HEMTs
2012 physica status solidi c, Band: 9, Nummer: 3-4, Seiten: 938 - 941
Binder S, Bartsch J, Glatthaar M, Glunz Stefan
Printed contact on emitter with low dopant surface concentration
2012 Energy Procedia, Band: 21, Seiten: 32 - 38
F. Gütle, V. M. Polyakov, M. Baeumler, F. Benkhelifa, S. Müller, M. Dammann, M. Cäsar, R. Quay, M. Mikulla, J. Wagner, O. Ambacher
Radiative inter-valley transitions as a dominant emission mechanism in AlGaN/GaN high electron mobility transistors
2012 Semicond Sci Tech, Band: 27, Nummer: 12, Seite: 125003
M. Dammann, H. Czap, J. Rüster, M. Baeumler, F. Gütle, P. Waltereit, F. Benkhelifa, R. Reiner, M. Cäsar, H. Konstanzer, S. Müller, R. Quay, M. Mikulla, O. Ambacher
Reverse bias stress test of GaN HEMTs for high-voltage switching applications
2012 IEEE International Integrated Reliability Workshop Final Report, Seiten: 105 - 108
F. Knöbber, V. Zürbig, N. Heidrich, J. Hees, R. E. Sah, M. Baeumler, S. Leopold, D. Pätz, O. Ambacher, V. Lebedev
Static and dynamic characterization of AlN and nanocrystalline diamond membranes
2012 Phys Status Solidi A, Band: 209, Nummer: 10, Seiten: 1835 - 1842
F. Balle, D. Eifler
Statistical test planning for ultrasonic welding of dissimilar materials using the example of aluminum‐carbon fiber reinforced polymers (CFRP) joints
2012 Materialwiss Werkst, Band: 43, Nummer: 4, Seiten: 286 - 292
Reiterer, A., Dambacher, M., Maindorfer, I., Höfler, H., Ebersbach, D., Frey, C., Scheller, S., Klose, D.
Straßenzustandserfassung – Neue Laserscanner-Technologie zur Ebenheitsmessung von Straßenbelägen
2012 VDV-Magazin, Band: Nr. 5
J. Antes, T. Mahler, T. Zwick, A. Tessmann, O. Ambacher, I. Kallfass
Study on data transmission of complex modulated signals using an MMIC-based 220 GHz wireless link
2012 International Symposium on Signals, Systems, and Electronics (ISSSE), Seiten: 1 - 4
Beaucarne G, Schubert G, Hoornstra J, Horzel J, Glunz S
Summary of the third workshop on metallization for crystalline silicon solar cells
2012 Energy Procedia, Band: 21, Seiten: 2 - 13
M. Himmerlich, S. Krischok, C. Wang, V. Cimalla, O. Ambacher
Surface chemical and electronic properties of In2O3 and In2O3-x nanoparticles for ozone detection
2012 Verhandlungen der Deutschen Physikalischen Gesellschaft
M. Himmerlich, Ch. Y. Wang, V. Cimalla, O. Ambacher, S. Krischok
Surface properties of stoichiometric and defect-rich indium oxide films grown by MOCVD
2012 J Appl Phys, Band: 111, Nummer: 9, Seite: 093704
Reiterer, A., Wagner, A.
System Considerations of an Image-Assisted Total Station – Evaluation and Assessment.
2012 Allgemeine Vermessungs-Nachrichten, Band: 3, Seiten: 83 - 94
J. M. Mánuel, F. M. Morales, R. García, R. Aidam, L. Kirste, O. Ambacher
Threading dislocation propagation in AlGaN/GaN based HEMT structures grown on Si (111) by plasma assisted molecular beam epitaxy
2012 J Cryst Growth, Band: 357, Seiten: 35 - 41
P. Waltereit, W. Bronner, R. Kiefer, R. Quay, M. Dammmann, M. Cäsar, P. Brückner, S. Müller, M. Mikulla, O. Ambacher
Trade‐offs between performance and reliability in AlGaN/GaN transistors
2012 physica status solidi c, Band: 9, Nummer: 2, Seiten: 365 - 368
D. Backe, F. Balle, T.B. Helfen, U. Rabe, S. Hirsekorn, C. Sklarczyk, D. Eifler, C. Boiler
Ultrasonic Fatigue Testing System Combined with Online Nondestructive Testing for Carbon Fiber Reinforced Composites
2012 Supplemental Proceedings: Materials Properties, Characterization, and Modeling, Band: 1, Seiten: 855 - 862
S. Heinz, F. Balle, G. Wagner, D. Eifler
Ultrasonic Fatigue of Ti6Al4V in the Very High Cycle Fatigue Regime
2012 Supplemental Proceedings: Materials Properties, Characterization, and Modeling, Band: 1, Seiten: 831 - 838
G. Wagner, F. Balle, D. Eifler
Ultrasonic welding of hybrid joints
2012 Jom-us, Band: 64, Nummer: 3, Seiten: 401 - 406
Saint-Cast P, Richter A, Billot E, Hofmann M, Benick J, Rentsch J, Preu R, Glunz S
Very low surface recombination velocity of boron doped emitter passivated with plasma-enhanced chemical-vapor-deposited AlOx layers
2012 Thin Solid Films, Band: 522, Seiten: 336 - 339
Hiermaier S, Huberth F
Volume dilatation in a polycarbonate blend at varying strain rates
2012 European physical journal special topics, Band: 206, Nummer: 1, Seiten: 173 - 181
KurzfassungImpact loaded polymers show a variety of strain-rate dependent mechanical properties in their elastic, plastic and failure behaviour. In contrast to purely crystalline materials, the volume of polymeric materials can significantly change under irreversible deformations. In this paper, uni-axial tensile tests were performed in order to measure the dilatation in the Polycarbonate-Acrylnitril-Butadien-Styrol (PC-ABS) Bayblend T65. The accumulation of dilatation was measured at deformation speeds of 0. 1 and 500 [mm/s]. Instrumented with a pair of two high-speed cameras, volume segments in the samples were observed. The change in volume was quantified as relation between the deformed and initial volumes of the segments. It was observed that the measured dilatations are of great significance for the constitutive models. This is specifically demonstrated through comparisons of stress-strain relations derived from the two camera-perspectives with isochoric relations based on s ingle-surface observations of the same experiments.
Hiermaier, S., Huberth, F.
Volume dilatation in a polycarbonate blend at varying strain rates
2012 European physical journal special topics, Band: 206, Seiten: 173 - 181
KurzfassungImpact loaded polymers show a variety of strain-rate dependent mechanical properties in their elastic, plastic and failure behaviour. In contrast to purely crystalline materials, the volume of polymeric materials can significantly change under irreversible deformations. In this paper, uni-axial tensile tests were performed in order to measure the dilatation in the Polycarbonate-Acrylnitril-Butadien-Styrol (PC-ABS) Bayblend T65. The accumulation of dilatation was measured at deformation speeds of 0. 1 and 500 [mm/s]. Instrumented with a pair of two high-speed cameras, volume segments in the samples were observed. The change in volume was quantified as relation between the deformed and initial volumes of the segments. It was observed that the measured dilatations are of great significance for the constitutive models. This is specifically demonstrated through comparisons of stress-strain relations derived from the two camera-perspectives with isochoric relations based on s ingle-surface observations of the same experiments.
S. Diebold, D. Goetzl, S. Ayhan, S. Scherr, P. Pahl, H. Massler, A. Tessmann, A. Leuther, O. Ambacher, T. Zwick, I. Kallfass
W-band MMIC radar modules for remote detection of vital signs
2012 7th European Microwave Integrated Circuit Conference, Seiten: 195 - 198
J. Antes, D. Lopez-Diaz, A. Tessmann, A. Leuther, H. Massler, T. Zwick, O. Ambacher, I. Kallfass
Wireless multi-gigabit data transmission using active MMIC components at 220 GHz
2012 International Journal of Microwave and Wireless Technologies, Band: 4, Nummer: 3, Seiten: 291 - 298

2011

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B. Rösener, S. Kaspar, M. Rattunde, T. Töpper, C. Manz, K. Köhler, O. Ambacher, J. Wagner
2 μm semiconductor disk laser with a heterodyne linewidth below 10 kHz
2011 Opt Lett, Band: 36, Nummer: 18, Seiten: 3587 - 3589
A. Leuther, S. Koch, A. Tessmann, I. Kallfass, T. Merkle, H. Massler, R. Loesch, M. Schlechtweg, S. Saito, O. Ambacher
20 nm metamorphic HEMT with 660 GHz fT
2011 IPRM -23rd International Conference on Indium Phosphide and Related Materials, Seiten: 1 - 4
Q. Yang, O. Ambacher
9.4 Quantum cascade lasers
2011 Laser Systems, Seiten: 74 - 86
I. Kallfass, H. Massler, S. Wagner, D. Schwantuschke, P. Brückner, C. Haupt, R. Kiefer, R. Quay, O. Ambacher
A highly linear 84 GHz low noise amplifier MMIC in AlGaN/GaN HEMT technology
2011 IEEE MTT-S International Microwave Workshop Series on Millimeter Wave Integration Technologies, Seiten: 144 - 147
May M, Nossek M, Hiermaier S
A multi-scale methodology for the evaluation of different fiber-matrix combinations using the generalized method of cells
2011
May M, Nossek M, Petrinic N, Hiermaier S
A new rate dependent cohesive zone model for impact applications
2011 , Seiten: 137 - 144
D. Bruch, F. Schäfer, M. Seelmann-Eggebert, B. Aja, I. Kallfass, A. Leuther, M. Schlechtweg, O. Ambacher
A single chip broadband noise source for noise measurements at cryogenic temperatures
2011 IEEE MTT-S International Microwave Symposium, Seiten: 1 - 4
I. Kallfass, R. Quay, H. Massler, S. Wagner, D. Schwantuschke, C. Haupt, R. Kiefer, O. Ambacher
A single-chip 77 GHz heterodyne receiver MMIC in 100 nm AlGaN/GaN HEMT technology
2011 IEEE MTT-S International Microwave Symposium, Seiten: 1 - 4
Rüdiger M, Rauer M, Schmiga C, Hermle M, Glunz Stefan
Accurate modeling of aluminum-doped silicon
2011 Energy Procedia, Band: 8, Seiten: 527 - 532
C. Zech, A. Hülsmann, I. Kallfass, A. Tessmann, M. Zink, M. Schlechtweg, A. Leuther, O. Ambacher
Active millimeter-wave imaging system for material analysis and object detection
2011 Millimetre Wave and Terahertz Sensors and Technology IV, Band: 8188, Seite: 81880D
D. Krausse, F. Benkhelifa, R. Reiner, R. Quay, O. Ambacher
AlGaN/GaN power amplifiers for ISM frequency applications
2011 Proceedings of the European Solid-State Device Research Conference (ESSDERC), Seiten: 283 - 286
N. Heidrich, F. Knoebber, O. Ambacher, V. Lebedev, R. E. Sah, V. Cimalla
AlN-based microstructures for biocompatible piezo-generation
2011 Verhandlungen der Deutschen Physikalischen Gesellschaft
N. Heidrich, F. Knöbber, S. Hampl, W. Pletschen, R.E. Sah, V. Cimalla, V. Lebedev, O. Ambacher
AlN-basierte mikroelektromechanische Strukturen für Implantate
2011 Proc. MST-Kongress, Band: 10, Seite: 12
Pysch D, Bivour M, Hermle M, Glunz Stefan
Amorphous silicon carbide heterojunction solar cells on p-type substrates
2011 Thin Solid Films, Band: 519, Nummer: 8, Seiten: 2550 - 2554
Pysch D, Meinhard C, Harder N.-P., Hermle M, Glunz Stefan
Analysis and optimization approach for the doped amorphous layers of silicon heterojunction solar cells
2011 Journal of Applied Physics, Band: 110, Nummer: 9
M. Musser, R. Quay, F. Van Raay, M. Mikulla, O. Ambacher
Analysis of GaN HEMTs for broadband high-power amplifier design
2011 6th European Microwave Integrated Circuit Conference, Seiten: 128 - 131
Bivour M, Rüdiger M, Reichel C, Ritzau K.-U., Hermle M, Glunz Stefan
Analysis of the diffused front surface field of n-type silicon solar cells with a-Si/c-Si heterojunction rear emitter
2011 Energy Procedia, Band: 8, Seiten: 185 - 192
Reiterer, A., Wasmeier, P.
Anwendungsfelder bildgebender Tachymetrie – Herausforderungen und Perspektiven
2011 Terrestrisches Laserscanning TLS 2011, DVW-Schriftenreihe
R. Driad, F. Benkhelifa, L. Kirste, M. Mikulla, O. Ambacher
Atomic Layer Deposition of Aluminum Oxide for Surface Passivation of InGaAs/InP Heterojunction Bipolar Transistors
2011 J Electrochem Soc, Band: 158, Nummer: 12, Seite: H1279
S. Maroldt, R. Quay, C. Haupt, O. Ambacher
Broadband GaN-based switch-mode core MMICs with 20 W output power operating at UHF
2011 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
Balestrieri M, Pysch D, Becker J.-P., Hermle M, Warta W, Glunz Stefan
Characterization and optimization of indium tin oxide films for heterojunction solar cells
2011 Solar Energy Materials and Solar Cells, Band: 95, Nummer: 8, Seiten: 2390 - 2399
M. Cäsar, M. Dammann, V. Polyakov, P. Waltereit, R. Quay, M. Mikulla, O. Ambacher
Critical factors influencing the voltage robustness of AlGaN/GaN HEMTs
2011 Microelectron Reliab, Band: 51, Nummer: 2, Seiten: 224 - 228
S. U. Schwarz, S. Linkohr, P. Lorenz, S. Krischok, T. Nakamura, V. Cimalla, C. E. Nebel, O. Ambacher
DNA‐sensor based on AlGaN/GaN high electron mobility transistor
2011 physica status solidi (a), Band: 208, Nummer: 7, Seiten: 1626 - 1629
N. Konchakova, R. Mueller, F.J. Barth, F. Balle, D. Eifler
Damage Evolution in Ultrasonic Welded Aluminum/Fiber‐Reinforced Polymer Joints with Different Welding Geometries
2011 Supplemental Proceedings: Materials Properties, Characterization, and Modeling, Band: 2, Seiten: 601 - 608
F. Balle, S. Huxhold, G. Wagner, D. Eifler
Damage monitoring of ultrasonically welded aluminum/CFRP-joints by electrical resistance measurements
2011 Procedia Engineering, Band: 10, Seiten: 433 - 438
S. Diebold, I. Kallfass, H. Massler, M. Seelmann-Eggebert, A. Leuther, A. Tessmann, P. Pahl, S. Koch, O. Ambacher
Design and model studies for solid-state power amplification at 210 GHz
2011 International Journal of Microwave and Wireless Technologies, Band: 3, Nummer: 3, Seite: 339
C. Haupt, S. Maroldt, R. Quay, W. Pletschen, A. Leuther, O. Ambacher
Development of a high transconductance GaN MMIC technology for millimeter wave applications
2011 physica status solidi c, Band: 8, Nummer: 2, Seiten: 297 - 299
C. Moeller, S. Shokhovets, G. Gobsch, K. Koehler, O. Ambacher
Dielectric functions of wurtzite GaN at elevated temperatures
2011 Verhandlungen der Deutschen Physikalischen Gesellschaft
R. Quay, A. Tessmann, R. Kiefer, S. Maroldt, C. Haupt, U. Nowotny, R. Weber, H. Massler, D. Schwantuschke, M. Seelmann-Eggebert, A. Leuther, M. Mikulla, O. Ambacher
Dual-gate GaN MMICs for MM-wave operation
2011 IEEE microwave and wireless components letters, Band: 21, Nummer: 2, Seiten: 95 - 97
F. Knöbber, O. Bludau, C.‐C. Röhlig, R.E. Sah, O.A. Williams, L. Kirste, S. Leopold, D. Pätz, V. Cimalla, O. Ambacher, V. Lebedev
Dynamic characterization of thin aluminum nitride microstructures
2011 physica status solidi c, Band: 8, Nummer: 2, Seiten: 479 - 481
Kamp M, Bartsch J, Nold S, Retzlaff M, Hörteis M, Glunz Stefan
Economic evaluation of two-step metallization processes for silicon solar cells
2011 Energy Procedia, Band: 8, Seiten: 558 - 564
Bartsch J, Kamp M, Hörteis M, Glunz Stefan, Gombert A, Reinecke H
Effects of seed layer and substrate morphology on solar cell contacts deposited by light-induced plating
2011 Journal of The Electrochemical Society, Band: 158, Nummer: 6, Seiten: H651 - 8
Bartsch J, Kamp M, Hörteis M, Glunz Stefan, Gombert A, Reinecke H
Effects of seed layer and substrate morphology on solar cell contacts deposited by light-induced plating
2011 Journal of The Electrochemical Society, Band: 158, Nummer: 6, Seiten: 651 - 658
K. Köhler, S. Müller, P. Waltereit, W. Pletschen, V. Polyakov, T. Lim, L. Kirste, H. P. Menner, P. Brückner, O. Ambacher, C. Buchheim, R. Goldhahn
Electrical properties of AlxGa1-xN/GaN heterostructures with low Al content
2011 J Appl Phys, Band: 109, Nummer: 5, Seite: 053705
V. Lebedev, V. Polyakov, A. Knübel, R. Aidam, L. Kirste, V. Cimalla, R. Granzner, F. Schwierz, O. Ambacher
Electron and hole accumulation in InN/InGaN heterostructures
2011 physica status solidi c, Band: 8, Nummer: 2, Seiten: 485 - 487
Various
Energy-Efficient Computing and Networking: First International Conference, E-Energy 2010, Athens, Revised Selected Papers
2011 Springer
Rosenits P, Roth T, Glunz Stefan
Erratum on “Determining the defect parameters of the deep aluminum-related defect center in silicon” [Appl. Phys. Lett. 91, 122109 (2007)]
2011 Applied Physics Letters, Band: 99, Nummer: 23
Richter A, Benick J, Hermle M, Glunz Stefan
Excellent silicon surface passivation with 5 Å thin ALD Al2O3 layers: Influence of different thermal post-deposition treatments: Influence of different thermal post-deposition treatments
2011 physica status solidi (RRL) - Rapid Research Letters, Band: 5, Nummer: 5-6, Seiten: 202 - 204
Goldschmidt J, Fischer S, Löper P, Krämer K, Biner D, Hermle M, Glunz Stefan
Experimental analysis of upconversion with both coherent monochromatic irradiation and broad spectrum illumination
2011 Solar Energy Materials and Solar Cells, Band: 95, Nummer: 7, Seiten: 1960 - 1963
Steingrube S, Breitenstein O, Ramspeck K, Glunz Stefan, Schenk A, Altermatt P
Explanation of commonly observed shunt currents in c-Si solar cells by means of recombination statistics beyond the Shockley-Read-Hall approximation
2011 Journal of Applied Physics, Band: 110, Nummer: 1
T. Lim, P. Waltereit, R. Aidam, R. Quay, L. Kirste, P. Bruckner, R. Kiefer, O. Ambacher
Fabrication of AlGaInN/GaN Transistors with ft and fmax Exceeding 100 GHz
2011 Minerals, Metals and Materials Society/AIME
W. Bronner, P. Waltereit, S. Müller, M. Dammann, R. Kiefer, Ph. Dennler, F. van Raay, M. Mußer, R. Quay, M. Mikulla, O. Ambacher
From epitaxy to backside process: Reproducible AlGaN/GaN HEMT technology for reliable and rugged power devices
2011 International Conference on Compound Semiconductor Manufacturing Technology
Rauer M, Schmiga C, Krause J, Woehl R, Hermle M, Glunz Stefan
Further analysis of aluminum alloying for the formation of p+ regions in silicon solar cells
2011 Energy Procedia, Band: 8, Seiten: 200 - 206
S. Maroldt, R. Quay, C. Haupt, R. Kiefer, D. Wiegner, O. Ambacher
GaN HFET MMICs with integrated Schottky-diode for highly efficient digital switch-mode power amplifiers at 2 GHz
2011 International Journal of Microwave and Wireless Technologies, Band: 3, Nummer: 3, Seite: 319
J. M. Mánuel, F. M. Morales, J. G. Lozano, R. García, T. Lim, L. Kirste, R. Aidam, O. Ambacher
Growth and characterization of InAlN layers nearly lattice‐matched to GaN
2011 physica status solidi c, Band: 8, Nummer: 7-8, Seiten: 2500 - 2502
Ch. Y. Wang, L. Kirste, F. M. Morales, J. M. Mánuel, C. C. Röhlig, K. Köhler, V. Cimalla, R. Garcia, O. Ambacher
Growth mechanism and electronic properties of epitaxial In2O3 films on sapphire
2011 J Appl Phys, Band: 110, Nummer: 9, Seite: 093712
D. Lopez-Diaz, I. Kallfass, A. Tessmann, R. Weber, H. Massler, A. Leuther, M. Schlechtweg, O. Ambacher
High-performance 60áGHz MMICs for wireless digital communication in 100ánm mHEMT technology
2011 International Journal of Microwave and Wireless Technologies, Band: 3, Nummer: 2, Seite: 107
Reichel C, Bivour M, Granek F, Hermle M, Glunz Stefan
Improved diffusion profiles in back-contacted back-junction Si solar cells with an overcompensated boron-doped emitter
2011 physica status solidi (a), Band: 208, Nummer: 12, Seiten: 2871 - 2883
J. M. Mánuel, F. M. Morales, R. García, T. Lim, L. Kirste, R. Aidam, O. Ambacher
Improved structural and chemical properties of nearly lattice-matched ternary and quaternary barriers for GaN-based HEMTs
2011 Cryst Growth Des, Band: 11, Nummer: 6, Seiten: 2588 - 2591
P. Schuh, H. Sledzik, M. Oppermann, R. Quay, J. Kühn, T. Lim, P. Waltereit, M. Mikulla, O. Ambacher
InAlGaN/GaN MMICs in microstrip transmission line technology for wideband applications
2011 6th European Microwave Integrated Circuit Conference, Seiten: 69 - 72
R. Driad, R. Aidam, Q. K. Yang, M. Maier, H. Güllich, M. Schlechtweg, O. Ambacher
InP-based heterojunction bipolar transistors with InGaAs/GaAs strained-layer-superlattice
2011 Appl Phys Lett, Band: 98, Nummer: 4, Seite: 043503
Rauer M, Schmiga C, Woehl R, Rühle K, Hermle M, Hörteis M, Biro D, Glunz Stefan
Investigation of aluminum-alloyed local contacts for rear surface-passivated silicon solar cells
2011 IEEE Journal of Photovoltaics, Band: 1, Nummer: 1, Seiten: 22 - 28
Reichel C, Granek F, Hermle M, Glunz Stefan
Investigation of electrical shading effects in back-contacted back-junction silicon solar cells using the two-dimensional charge collection probability and the reciprocity theorem
2011 Journal of Applied Physics, Band: 109, Nummer: 2
F. Balle, S. Schmeer, G. Wagner
Mechanische Charakterisierung ultraschallgeschweißter Aluminium/CFK-Verbunde bei automobilrelevanten Temperaturen und Prüfgeschwindigkeiten
2011 Mater Test, Band: 53, Seiten: 7 - 13
Durr N, Sauer M, Hiermaier S
Mesoscale modelling of failure in partially sintered metals
2011
Kalio A, Richter A, Hörteis M, Glunz Stefan
Metallization of N-type silicon solar cells using fine line printing techniques
2011 Energy Procedia, Band: 8, Seiten: 571 - 576
A. Tessmann, A. Leuther, V. Hurm, I. Kallfass, H. Massler, M. Kuri, M. Riessle, M. Zink, R. Lösch, M. Seelmann-Eggebert, M. Schlechtweg, O. Ambacher
Metamorphic HEMT MMICs and modules operating between 300 and 500 GHz
2011 IEEE J Solid-st Circ, Band: 46, Nummer: 10, Seiten: 2193 - 2202
L, Zhou, L. Kirste, T. Lim, R. Aidam, O. Ambacher, D. Smith
Microstructural Characterization of Closely-Lattice-Matched AlIn (Ga) N Alloys for High Electron Mobility Transistors
2011 Microsc Microanal, Band: 17, Nummer: S2, Seiten: 1354 - 1355
K. Brueckner, F. Niebelschuetz, K. Tonisch, Ch. Foerster, V. Cimalla, R. Stephan, J. Pezoldt, T. Stauden, O. Ambacher, M.A. Hein
Micro‐and nano‐electromechanical resonators based on SiC and group III‐nitrides for sensor applications
2011 Phys Status Solidi A, Band: 208, Nummer: 2, Seiten: 357 - 376
M. Schlechtweg, A. Tessmann, I. Kallfass, A. Leuther, V. Hurm, H. Massler, M. Riessle, R. Lösch, O. Ambacher
Millimeter-wave circuits and modules up to 500 GHz based on metamorphic HEMT technology for remote sensing and wireless communication applications
2011 IEEE 9th International New Circuits and systems conference, Seiten: 269 - 272
J. Antes, D. Lopez-Diaz, A. Tessmann, A. Leuther, H. Massler, T. Zwick, O. Ambacher, I. Kallfass
Mmic based wireless data transmission of a 12.5 gbit/s signal using a 220 ghz carrier
2011 41st European Microwave Conference, Seiten: 238 - 241
P. Dennler, F. van Raay, M. Seelmann-Eggebert, R. Quay, O. Ambacher
Modeling and realization of GaN-based dual-gate HEMTs and HPA MMICs for Ku-band applications
2011 IEEE MTT-S International Microwave Symposium, Seiten: 1 - 4
M. Rattunde, S. Kaspar, B. Rösener, T. Töpper, C. Manz, K. Köhler, O. Ambacher, J. Wagner
Narrow linewidth 2 µm GaSb-based semiconductor disk laser
2011 The European Conference on Lasers and Electro-Optics
Ganzenmueller G, Camp P
Phase behaviour and dynamics in primitive models of molecular ionic liquids
2011 1 SVIENTSITSKII STR, LVIV, 79011, UKRAINE CONDENSED MATTER PHYSICS, INST CONDENSED MATTER PHYSICS NATL ACAD SCIENCES UKRAINE, Band: 14, Nummer: 3
KurzfassungThe phase behaviour and dynamics of molecular ionic liquids are studied using primitive models and extensive computer simulations. The models account for size disparity between cation and anion, charge location on the cation, and cation-shape anisotropy, which are all prominent features of important materials such as room-temperature ionic liquids. The vapour-liquid phase diagrams are determined using high-precision Monte Carlo simulations, setting the scene for in-depth studies of ion dynamics in the liquid state. Molecular dynamics simulations are used to explore the structure, single-particle translational and rotational autocorrelation functions, cation orientational autocorrelations, self diffusion, viscosity, and frequency-dependent conductivity. The results reveal some of the molecular-scale mechanisms for charge transport, involving molecular translation, rotation, and association.
Ch. Y. Wang, R. W. Becker, T. Passow, W. Pletschen, K. Köhler, V. Cimalla, O. Ambacher
Photon stimulated sensor based on indium oxide nanoparticles I: Wide-concentration-range ozone monitoring in air
2011 Sensors and Actuators B: Chemical, Band: 152, Nummer: 2, Seiten: 235 - 240
M.-E. Kleemann, S. Shokhovets, G. Gobsch, O. Ambacher
Polaritonic effects in wide-gap semiconductors as a function of temperature
2011 Verhandlungen der Deutschen Physikalischen Gesellschaft
T. Lim, R. Aidam, P. Waltereit, W. Pletschen, R. Quay, L. Kirste, O. Ambacher
Quaternary barriers for improved performance of GaN‐based HEMTs
2011 physica status solidi c, Band: 8, Nummer: 7-8, Seiten: 2439 - 2441
Benick J, Zimmermann K, Spiegelman J, Hermle M, Glunz Stefan
Rear side passivation of PERC-type solar cells by wet oxides grown from purified steam
2011 Progress in Photovoltaics: Research and Applications, Band: 19, Nummer: 3, Seiten: 361 - 365
M. Dammann, M. Baeumler, F. Gütle, M. Cäsar, H. Walcher, P. Waltereit, W. Bronner, S. Müller, R. Kiefer, R. Quay, M. Mikulla, O. Ambacher, A. Graff, F. Altmann, M. Simon
Reliability and degradation mechanism of 0.25 µm AlGaN/GaN HEMTs under RF stress conditions
2011 IEEE International Integrated Reliability Workshop Final Report, Seiten: 42 - 46
GanzenmĂźller G, Hiermaier S, Steinhauser M
Shock-wave induced damage in lipid bilayers
2011 Soft matter, Band: 7, Nummer: 9, Seiten: 4307 - 4317
KurzfassungThe effects of shock-wave impact on the damage of lipid bilayer membranes are investigated with dissipative particle simulations at constant energy (DPDE). A coarse-grained model for the phospholipid bilayer in aqueous environment is employed, which models single lipids as short chains consisting of a hydrophilic head and two hydrophobic tail beads. Water is modeled by mapping four H2O molecules to one water bead. Using the DPDE method enables us to faithfully simulate the non-equilibrium shock-wave process with a coarse-grained model as the correct heat capacity can be recovered. At equilibrium, we obtain self-stabilizing bilayer structures that exhibit bending stiffness and compression modulus comparable to experimental measurements under physiological conditions. We study in detail the damage behavior of the coarse-grained lipid bilayer upon high-speed shock-wave impact as a function of shock impact velocity and bilayer stability. A single damage parameter based on an orientation dependent correlation function is introduced. We observe that mechanical bilayer stability has only small influence on the resulting damage after shock-wave impact, and inertial effects play almost no role. At shock-front velocities below less than or similar to 3000 ms(-1), we observe reversible damage, whereas for speeds greater than or similar to 3900 ms(-1) no such recovery, or self-repair of the bilayer, could be observed.
Ganzenmueller G, Hiermaier S, Steinhauser M
Shock-wave induced damage in lipid bilayers
2011 THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND SOFT MATTER, ROYAL SOC CHEMISTRY, Band: 7, Nummer: 9, Seiten: 4307 - 4317
KurzfassungThe effects of shock-wave impact on the damage of lipid bilayer membranes are investigated with dissipative particle simulations at constant energy (DPDE). A coarse-grained model for the phospholipid bilayer in aqueous environment is employed, which models single lipids as short chains consisting of a hydrophilic head and two hydrophobic tail beads. Water is modeled by mapping four H2O molecules to one water bead. Using the DPDE method enables us to faithfully simulate the non-equilibrium shock-wave process with a coarse-grained model as the correct heat capacity can be recovered. At equilibrium, we obtain self-stabilizing bilayer structures that exhibit bending stiffness and compression modulus comparable to experimental measurements under physiological conditions. We study in detail the damage behavior of the coarse-grained lipid bilayer upon high-speed shock-wave impact as a function of shock impact velocity and bilayer stability. A single damage parameter based on an orientation dependent correlation function is introduced. We observe that mechanical bilayer stability has only small influence on the resulting damage after shock-wave impact, and inertial effects play almost no role. At shock-front velocities below less than or similar to 3000 ms(-1), we observe reversible damage, whereas for speeds greater than or similar to 3900 ms(-1) no such recovery, or self-repair of the bilayer, could be observed.
Ganzenmueller, G.C., Hiermaier, S., Steinhauser, M.O.
Shock-wave induced damage in lipid bilayers: A dissipative particle dynamics simulation study
2011 Soft matter, Band: 7, Seiten: 4307 - 4317
KurzfassungThe effects of shock-wave impact on the damage of lipid bilayer membranes are investigated with dissipative particle simulations at constant energy (DPDE). A coarse-grained model for the phospholipid bilayer in aqueous environment is employed, which models single lipids as short chains consisting of a hydrophilic head and two hydrophobic tail beads. Water is modeled by mapping four H2O molecules to one water bead. Using the DPDE method enables us to faithfully simulate the non-equilibrium shock-wave process with a coarse-grained model as the correct heat capacity can be recovered. At equilibrium, we obtain self-stabilizing bilayer structures that exhibit bending stiffness and compression modulus comparable to experimental measurements under physiological conditions. We study in detail the damage behavior of the coarse-grained lipid bilayer upon high-speed shock-wave impact as a function of shock impact velocity and bilayer stability. A single damage parameter based on an orientation dependent correlation function is introduced. We observe that mechanical bilayer stability has only small influence on the resulting damage after shock-wave impact, and inertial effects play almost no role. At shock-front velocities below less than or similar to 3000 ms(-1), we observe reversible damage, whereas for speeds greater than or similar to 3900 ms(-1) no such recovery, or self-repair of the bilayer, could be observed.
Gradmann R, Loeper P, Künle M, Rothfelder M, Janz S, Hermle M, Glunz Stefan
Si and SiC nanocrystals in an amorphous SiC matrix: Formation and electrical properties
2011 physica status solidi (c), Band: 8, Nummer: 3, Seiten: 831 - 834
R. Reiner, F. Benkhelifa, D. Krausse, R. Quay, O. Ambacher
Simulation and analysis of low-resistance AlGaN/GaN HFET power switches
2011 14th European Conference on Power Electronics and Applications, Seiten: 1 - 10
S. Kaspar, B. Rösener, M. Rattunde, T. Töpper, C. Manz, K. Köhler, O. Ambacher, J. Wagner
Sub-MHz-linewidth 200-mW actively stabilized 2.3-μm semiconductor disk laser
2011 Ieee Photonic Tech L, Band: 23, Nummer: 20, Seiten: 1538 - 1540
R. Driad, F. Benkhelifa, L. Kirste, R. Lösch, M. Mikulla, O. Ambacher
Surface passivation of InGaAs/InP HBTs using atomic layer deposited Al2O3
2011 ECS Transactions, Band: 35, Nummer: 4, Seite: 205
Kok K, Warmer C, Karnouskos S, Weidlich A, Ringelstein J
Testes de casas inteligentes para implementação de smart grid
2011 Eletricidade Moderna, Seiten: 48 - 57
Richter A, Benick J, Kalio A, Seiffe J, Hörteis M, Hermle M, Glunz Stefan
Towards industrial n-type PERT silicon solar cells: rear passivation and metallization scheme: Rear passivation and metallization scheme
2011 Energy Procedia, Band: 8, Seiten: 479 - 486
S. Leopold, D. Paetz, F. Knoebber, T. Polster, O. Ambacher, S. Sinzinger, M. Hoffmann
Tunable refractive beam steering using aluminum nitride thermal actuators
2011 MEMS Adaptive Optics V, Band: 7931, Seite: 79310B
R. E. Makon, R. Driad, J. Rosenzweig, V. Hurm, C. Schubert, H. Walcher, M. Schlechtweg, O. Ambacher
Ultra-high-speed transmitter and receiver ICs for 100 Gbit/s ethernet using InP DHBTs
2011 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
S. Huxhold, F. Balle, G. Wagner, D. Eifler
Ultrasonic Welding of Hybrid Aluminum/CFRP‐Joints: Microstructure, Monotonic Properties and Fatigue Behavior
2011 Supplemental Proceedings: Materials Processing and Energy Materials, Band: 1, Seiten: 743 - 748
Saint-Cast P, Heo Y.-H., Billot E, Olwal P, Hofmann M, Rentsch J, Glunz Stefan, Preu R
Variation of the layer thickness to study the electrical property of PECVD Al2O3 / c-Si interface
2011 Energy Procedia, Band: 8, Seiten: 642 - 647
I. Kallfass, A. Huelsmann, A. Tessmann, A. Leuther, E. Weissbrodt, M. Schlechtweg, O. Ambacher
W-band direct detection radiometers using metamorphic HEMT technology
2011 Passive Millimeter-Wave Imaging Technology XIV, Band: 8022, Seite: 80220O
E. Weissbrodt, I. Kallfass, A. Hülsmann, A. Tessmann, A. Leuther, H. Massler, O. Ambacher
W-band radiometer system with switching front-end for multi-load calibration
2011 IEEE International Geoscience and Remote Sensing Symposium, Seiten: 3843 - 3846

2010

nach oben zur Jahresübersicht

R.E. Makon, R. Driad, C. Schubert, J. Fischer, R. Lösch, H. Walcher, J. Rosenzweig, M. Schlechtweg, O. Ambacher
107–112 Gbit/s fully integrated CDR/1: 2 DEMUX using InP-based DHBTs
2010 The 5th European Microwave Integrated Circuits Conference, Seiten: 206 - 209
D. Lopez-Diaz, I. Kallfass, A. Tessmann, H. Massler, A. Leuther, M. Schlechtweg, O. Ambacher
A balanced resistive 210 ghz mixer with 50 ghz if bandwidth
2010 The 5th European Microwave Integrated Circuits Conference, Seiten: 190 - 193
S. Linkohr, S. Schwarz, S. Krischok, P. Lorenz, V. Cimalla, Ch. Nebel, O. Ambacher
A novel bio‐functionalization of AlGaN/GaN‐ISFETs for DNA‐sensors
2010 physica status solidi c, Band: 7, Nummer: 7-8, Seiten: 1810 - 1813
V. Cimalla, C.-C. Röhlig, V. Lebedev, O. Ambacher, K. Tonisch, F. Niebelschütz, P. Brueckner, M. A. Hein
AlGaN/GaN based heterostructures for MEMS and NEMS applications
2010 Solid State Phenomena, Band: 159, Seiten: 27 - 38
P. Waltereit, W. Bronner, R. Quay, M. Dammann, R. Kiefer, W. Pletschen, S. Müller, R. Aidam, H. Menner, L. Kirste, K. Köhler, M. Mikulla, O. Ambacher
AlGaN/GaN epitaxy and technology
2010 International journal of microwave and wireless technologies, Band: 2, Nummer: 1
F. Knoebber, O. Bludau, C.-C. Roehlig, O. Williams, R. E. Sah, L. Kirste, V. Cimalla, V. Lebedev, C. Nebel, O. Ambacher
Aluminum nitride and nanodiamond thin film microstructures
2010 Verhandlungen der Deutschen Physikalischen Gesellschaft
Reiterer, A., Egly, U., Vicovac, T., Mai, E., Moafipoor, S., Grejner-Brzezinska, D.A. Toth, C.K.
Application of Artificial Intelligence in Geodesy – A Review of Theoretical Foundations and Practical Examples
2010 Journal of Applied Geodesy, Band: 4, Seiten: 201 - 217
Hiermaier S, Meenken T
Characterization of low-impedance materials at elevated strain rates
2010 The journal of strain analysis for engineering design, Band: 45, Nummer: 6, Seiten: 401 - 409
KurzfassungExperimental characterization of materials at elevated strain rates of the order of 10(3) s(-1) is typically performed by Hopkinson-bar-type facilities. The specific nature of Hopkinson bar tests is that a specimen is loaded by waves. As both the input and output bars are often made from high-impedance metallic materials, the ratio between transmitted and reflected wave components is very poor in the case of low-impedance specimen materials such as rubbers and foams. That poor wave transmission brings with it a limited quality of the signal-to-noise ratio. Changing the bar materials (e.g. to polycarbonate) is of little help because of the related viscous effects. A further deficiency of the wave-driven Hopkinson bar test for many rubber and foam applications is the comparably small amount of compression that is achievable. Maximum compressions of 95 per cent and above, often expected for damping and energy absorption applications, are out of the range of most Hopkinson bar set-ups. In order to overcome these deficiencies, first a split Hopkinson pressure bar (SHPB) facility was equipped with polyvinylidenefluoride (PVDF) thin-film sensors. Second, a direct-impact set-up for low-impedance materials was developed and calibrated at the Ernst Mach Institute (EMI). With the PVDF gauges, the range of application both for the SHPB and for the new set-up was enhanced. This is demonstrated with an SHPB-based investigation of stress homogeneity in polyurethane (PU) specimens. The direct-impact facility made it possible to derive the stress-strain relations for PU-rubber up to strain rates in the range of several 10(3) s(-1). Maximum compressions of more than 95 per cent were achieved. The paper describes the limitations of a classic SHPB set-up applied to low-impedance materials. The problem of stress homogeneity is addressed, and a set-up for a new direct-impact facility is presented. As an example application, a Confor-Blue foam, typically used for automotive crash-test dummies, is characterized at strain rates between 160 and 1115 s(-1).
Hiermaier, S., Meenken, T.
Characterization of low-impedance materials at elevated strain rates
2010 The journal of strain analysis for engineering design, Band: 45, Seiten: 401 - 409
KurzfassungExperimental characterization of materials at elevated strain rates of the order of 10(3) s(-1) is typically performed by Hopkinson-bar-type facilities. The specific nature of Hopkinson bar tests is that a specimen is loaded by waves. As both the input and output bars are often made from high-impedance metallic materials, the ratio between transmitted and reflected wave components is very poor in the case of low-impedance specimen materials such as rubbers and foams. That poor wave transmission brings with it a limited quality of the signal-to-noise ratio. Changing the bar materials (e.g. to polycarbonate) is of little help because of the related viscous effects. A further deficiency of the wave-driven Hopkinson bar test for many rubber and foam applications is the comparably small amount of compression that is achievable. Maximum compressions of 95 per cent and above, often expected for damping and energy absorption applications, are out of the range of most Hopkinson bar set-ups. In order to overcome these deficiencies, first a split Hopkinson pressure bar (SHPB) facility was equipped with polyvinylidenefluoride (PVDF) thin-film sensors. Second, a direct-impact set-up for low-impedance materials was developed and calibrated at the Ernst Mach Institute (EMI). With the PVDF gauges, the range of application both for the SHPB and for the new set-up was enhanced. This is demonstrated with an SHPB-based investigation of stress homogeneity in polyurethane (PU) specimens. The direct-impact facility made it possible to derive the stress-strain relations for PU-rubber up to strain rates in the range of several 10(3) s(-1). Maximum compressions of more than 95 per cent were achieved. The paper describes the limitations of a classic SHPB set-up applied to low-impedance materials. The problem of stress homogeneity is addressed, and a set-up for a new direct-impact facility is presented. As an example application, a Confor-Blue foam, typically used for automotive crash-test dummies, is characterized at strain rates between 160 and 1115 s(-1).
Ganzenmueller G, Patey G
Charge Ordering Induces a Smectic Phase in Oblate Ionic Liquid Crystals
2010 ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA PHYSICAL REVIEW LETTERS, AMER PHYSICAL SOC, Band: 105, Nummer: 13
KurzfassungWe report a computer simulation study of an electroneutral mixture of oppositely charged oblate ellipsoids of revolution with aspect ratio A = 1/3. In contrast with hard or soft repulsive ellipsoids, which are purely nematic, this system exhibits a smectic-A phase in which charges of equal sign are counter-intuitively packed in layers perpendicular to the nematic director.
F. Balle, G. Wagner, D. Eifler
Combined process of ultrasonic welding and precipitation hardening of aluminum alloy 2024/carbon fibre reinforced composites structures
2010 12th International Conference on Aluminum Alloys, Band: 12, Seiten: 5 - 9
T. Lim, R. Aidam, L. Kirste, P. Waltereit, R. Quay, S. Müller, O. Ambacher
Compositional variation of nearly lattice-matched InAlGaN alloys for high electron mobility transistors
2010 Appl Phys Lett, Band: 96, Nummer: 25, Seite: 252108
J. Kühn, M. Musser, F. van Raay, R. Kiefer, M. Seelmann-Eggebert, M. Mikulla, R. Quay, T. Rödle, O. Ambacher
Design and realization of GaN RF-devices and circuits from 1 to 30 GHz
2010 International Journal of Microwave and Wireless Technologies, Band: 2, Nummer: 1, Seiten: 115 - 120
T. Lim, R. Aidam, L. Kirste, P. Waltereit, S. Müller, O. Ambacher
Design of near lattice‐matched AlGaInN‐barriers for highly‐scalable GaN‐based transistor structures
2010 physica status solidi c, Band: 7, Nummer: 7-8, Seiten: 1958 - 1960
S. Diebold, I. Kallfass, H. Massler, A. Leuther, A. Tessmann, P. Pahl, S. Koch, M. Siegel, O. Ambacher
Determination of suitable mHEMT transistor dimensioning for power amplification at 210 GHz by comprehensive measurements
2010 The 5th European Microwave Integrated Circuits Conference, Seiten: 78 - 81
P. Waltereit, W. Bronner, R. Quay, M. Dammann, S. Müller, K. Köhler, M. Mikulla, O. Ambacher, L. Harm, M. Lorenzini, T. Rödle, K. Riepe, K. Bellmann, C. Buchheim, R. Goldhahn
Development of rugged 2 GHz power bars delivering more than 100 W and 60% power added efficiency
2010 physica status solidi c, Band: 7, Nummer: 10, Seiten: 2398 - 2403
J. Kühn, F. van Raay, R. Quay, R. Kiefer, M. Mikulla, M. Seelmann-Eggebert, W. Bronner, M. Schlechtweg, O. Ambacher, M. Thumm
Device and Design Optimization for AlGaN/GaN X-Band-Power-Amplifiers with High Efficiency
2010 J Infrared Millim Te
F. Knöbber, O. Bludau, O.A. Williams, R.E. Sah, L. Kirste, M. Baeumler, S. Leopold, D. Pätz, C.E. Nebel, O. Ambacher, V. Cimalla, V. Lebedev
Diamond/AlN Thin Films for Optical Applications
2010 AIP Conference Proceedings, Band: 1292, Nummer: 1, Seiten: 205 - 208
Rauer M, Schmiga C, Hermle M, Glunz Stefan
Effectively surface-passivated aluminium-doped p+ emitters for n-type silicon solar cells
2010 physica status solidi (a), Band: 207, Nummer: 5, Seiten: 1249 - 1251
S. Maroldt, D. Wiegner, S. Vitanov, V. Palankovski, R. Quay, O. Ambacher
Efficient AlGaN/GaN linear and digital-switch-mode power amplifiers for operation at 2 GHz
2010 Ieice T Electron, Band: 93, Nummer: 8, Seiten: 1238 - 1244
C.-C. Röhlig, F. Niebelschütz, P. Brueckner, K. Tonisch, O. Ambacher, V. Cimalla
Elastic properties of nanowires
2010 Phys Status Solidi B, Band: 247, Nummer: 10, Seiten: 2557 - 2570
Hörteis M, Bartsch J, Binder S, Filipovic A, Merkel J, RAdtke V, Glunz Stefan
Electrical properties of fine line printed and light-induced plated contacts on silicon solar cells
2010 Progress in Photovoltaics: Research and Applications, Band: 18, Nummer: 4
Bartsch J, RAdtke V, Schetter C, Glunz Stefan
Electrochemical methods to analyse the light-induced plating process
2010 Journal of Applied Electrochemistry, Band: 40, Nummer: 4, Seiten: 757 - 765
Reichel C, Granek F, Hermle M, Glunz Stefan
Enhanced current collection in back-contacted back-junction Si solar cells by overcompensating a boron emitter with a phosphorus base-type doping
2010 physica status solidi (a), Band: 207, Nummer: 8, Seiten: 1978 - 1981
Fischer S, Goldschmidt J, Löper P, Bauer G, Brüggemann R, Krämer K, Biner D, Hermle M, Glunz Stefan
Enhancement of silicon solar cell efficiency by upconversion: Optical and electrical characterization
2010 Journal of Applied Physics, Band: 108, Nummer: 4
N. Konchakova, F. Balle, F.J. Barth, R. Mueller, D. Eifler, P. Steinmann
Finite element analysis of an inelastic interface in ultrasonic welded metal/fibre-reinforced polymer joints
2010 Comp Mater Sci, Band: 50, Nummer: 1, Seiten: 184 - 190
S. U. Schwarz, V. Cimalla, C. Nebel, O. Ambacher
Functionalization of AlGaN/GaN heterostructures with TFAAD
2010 Verhandlungen der Deutschen Physikalischen Gesellschaft
Eglseer, A., Reiterer, A., Eichhorn, A.
Fußgängerortung im Out- und Indoorbereich mit einem autonomen Ortungssystem
2010 Allgemeine Vermessungs-Nachrichten, Band: Nr. 07, Seiten: 243 - 249
M. Musser, H. Walcher, T. Maier, R. Quay, M. Dammann, M. Mikulla, O. Ambacher
GaN power FETs for next generation mobile communication systems
2010 The 5th European Microwave Integrated Circuits Conference, Seiten: 9 - 12
T Lim, R Aidam, P Waltereit, T, Henkel, R Quay, R Lozar, T, Maier, L Kirste, O Ambacher
GaN-based submicrometer HEMTs with lattice-matched InAlGaN barrier grown by MBE
2010 Ieee Electr Device L, Band: 31, Nummer: 7, Seiten: 671 - 673
J. Kühn, P. Waltereit, F. van Raay, R. Aidam, R. Quay, O. Ambacher, M. Thumm
Harmonic termination of AlGaN/GaN/(Al) GaN-single-and double-heterojunction HEMTs
2010 German Microwave Conference Digest of Papers, Seiten: 122 - 125
P. Waltereit, W. Bronner, R. Kiefer, R. Quay, J. Kühn, F. Van Raay, M. Dammann, S. Müller, C. Libal, T. Meier, M. Mikulla, O. Ambacher
High efficiency and low leakage AlGaN/GaN HEMTs for a robust, reproducible and reliable X-band MMIC space technology
2010 Proceedings of the CS Mantech Conference
Saint-Cast P, Benick J, Kania D, Weiss L, Hofmann M, Rentsch J, Preu R, Glunz Stefan
High-Efficiency c-Si Solar Cells Passivated With ALD and PECVD Aluminum Oxide
2010 IEEE Electron Device Letters, Band: 31, Nummer: 7, Seiten: 695 - 697
Hörteis M, Gutberlet T, Reller A, Glunz Stefan
High-temperature contact formation on n-Type silicon: basic reactions and contact model for Seed-Layer contacts: Basic reactions and contact model for seed-layer contacts
2010 Advanced Functional Materials, Band: 20, Nummer: 3, Seiten: 476 - 484
Reiterer, A., Huber, B.N., Bauer, A.
Image-Based Point Detection and Matching in a Geo-Monitoring System
2010 Allgemeine Vermessungs-Nachrichten, Band: Nr. 4, Seiten: 129 - 139
V.M. Polyakov, V. Cimalla, V. Lebedev, K. Köhler, S. Müller, P. Waltereit, O. Ambacher
Impact of Al content on transport properties of two-dimensional electron gas in GaN/Al(x)Ga(1-x)N/GaN heterostructures
2010 Appl Phys Lett, Band: 97, Nummer: 14, Seite: 142112
Suwito D, Jager U, Benick J, Janz S, Hermle M, Glunz Stefan
Industrially Feasible Rear Passivation and Contacting Scheme for High-Efficiency n-Type Solar Cells Yielding a Voc of 700 mV
2010 IEEE Transactions on Electron Devices, Band: 57, Nummer: 8, Seiten: 2032 - 2036
W. Pletschen, R. Kiefer, S. Maroldt, S. Müller, R. Quay, M. Mikulla, O. Ambacher
Influence of Dry Etch Conditions on the Performance of Recessed Gate GaN/AlGaN HEMTs
2010 ECS Transactions, Band: 33, Nummer: 13, Seite: 61
Rosenits P, Roth T, Warta W, Glunz Stefan
Influence of different excitation spectra on the measured carrier lifetimes in quasi-steady-state photoconductance measurements
2010 Solar Energy Materials and Solar Cells, Band: 94, Nummer: 5, Seiten: 767 - 773
K. Koehler, S. Mueller, R. Aidam, P. Waltereit, W. Pletschen, L. Kirste, H.P. Menner, W. Bronner, A. Leuther, R. Quay, M. Mikulla, O. Ambacher, R. Granzner, F. Schwierz, C. Buchheim, R. Goldhahn
Influence of the surface potential on electrical properties of Al(x)Ga(1-x)N/GaN heterostructures with different Al-content: Effect of growth method
2010 J Appl Phys, Band: 107, Nummer: 5
S. Maroldt, R. Quay, C. Haupt, R. Kiefer, D. Wiegner, O. Ambacher
Integrated-Schottky-diode GaN HFETs for high-efficiency digital PA MMICs at 2 GHz
2010 The 40th European Microwave Conference, Seiten: 636 - 639
9M. Baeumler, F. Gütle, V. M. Polyakov, M. Cäsar, M. Dammann, H. Konstanzer, W. Pletschen, W. Bronner, R. Quay, P. Waltereit, M. Mikulla, O. Ambacher, F. Bourgeois, R. Behtash, K. Riepe, P. J. van der Wel, J. Klappe, T. Rödle
Investigation of leakage current of AlGaN/GaN HEMTs under pinch-off condition by electroluminescence microscopy
2010 J Electron Mater, Band: 39, Nummer: 6, Seiten: 756 - 760
A. Leuther, A. Tessmann, I. Kallfass, H. Massler, R. Loesch, M. Schlechtweg, M. Mikulla, O. Ambacher
Metamorphic HEMT technology for submillimeter-wave MMIC applications
2010 22nd International Conference on Indium Phosphide and Related Materials (IPRM), Seiten: 1 - 6
Kluska S, Granek F, Rüdiger M, Hermle M, Glunz Stefan
Modeling and optimization study of industrial n-type high-efficiency back-contact back-junction silicon solar cells
2010 Solar Energy Materials and Solar Cells, Band: 94, Nummer: 3, Seiten: 568 - 577
D. Lopez-Diaz, I. Kallfass, A. Tessmann, H. Massler, A. Leuther, M. Schlechtweg, O. Ambacher
Monolithic integrated 210 GHz couplers for balanced mixers and image rejection mixers
2010 Workshop on Integrated Nonlinear Microwave and Millimeter-Wave Circuits, Seiten: 58 - 6
Ch. Y. Wang, V. Cimalla, M. Kunzer, T. Passow, W. Pletschen, O. Kappeler, J. Wagner, O. Ambacher
Near‐UV LEDs for integrated InO‐based ozone sensors
2010 physica status solidi c, Band: 7, Nummer: 7-8, Seiten: 2177 - 2179
F. Niebelschuetz, K. Brueckner, K. Tonisch, R. Stephan, V. Cimalla, O. Ambacher, M.A. Hein
Piezoelectric actuated epitaxially grown AlGaN/GaN‐resonators
2010 physica status solidi c, Band: 7, Nummer: 7-8, Seiten: 1829 - 1831
Bartsch J, Mondon A, Bayer K, Schetter C, Hörteis M, Glunz Stefan
Quick determination of copper-metallization long-term impact on silicon solar cells
2010 Journal of The Electrochemical Society, Band: 157, Nummer: 10
J.M. Mánuel, F.M. Morales, J.G. Lozano, D. González, R. García, T. Lim, L. Kirste, R. Aidam, O. Ambacher
Structural and compositional homogeneity of InAlN epitaxial layers nearly lattice-matched to GaN
2010 Acta Mater, Band: 58, Nummer: 12, Seiten: 4120 - 4125
L. Kirste, T. Lim, R. Aidam, S. Müller, P. Waltereit, O. Ambacher
Structural properties of MBE AlInN and AlGaInN barrier layers for GaN‐HEMT structures
2010 Phys Status Solidi A, Band: 207, Nummer: 6, Seiten: 1338 - 1341
D. Lopez-Diaz, I. Kallfass, A. Tessmann, A. Leuther, H. Massler, M. Schlechtweg, O. Ambacher
Subharmonically pumped 210 GHz i/q mixers
2010 IEEE Compound Semiconductor Integrated Circuit Symposium (CSICS), Seiten: 1 - 4
Hiermaier S, Riedel W, Thoma K
Tragwerke unter Anprall und Explosion - Experimentelle und numerische Methoden zur Auslegung
2010 , Seiten: 93 - 118
Riedel W, Hiermaier S, Thoma K
Transient stress and failure analysis of impact experiments with ceramics
2010 , Seiten: 139 - 147
KurzfassungAt Ernst-Mach-Institut (EMI), ductile and brittle materials are studied both experimentally and numerically with the focus on shock and impact loading and associated damage effects. Experimental investigations using plate impact, edge-on impact, penetration and perforation on light gas accelerators provide input for numerical studies and allow verification of constitutive models. Hydrocodes are the standard numerical tool for the simulation of transient processes and basis of the modelling in the present paper. Besides use of commercial codes with mesh-based Lagrangean and Eulerian spatial discretization, an own meshfree SPH code has been developed at EMI. Edge-on impact experiments, plate impact tests and deep penetration in confined targets are simulated to study different loading histories and failure conditions. Significantly different material models based on continuum damage approaches as well as microstatistical modelling of inhomogeneities have been implemented. Their performances in reproducing damage fracture patterns and continued fragment loading in different ceramic types are analysed and compared to edge-on impact experiments.
D. Pätz, S. Leopold, F. Knöbber, S. Sinzinger, M. Hoffmann, O. Ambacher
Tunable compound eye cameras
2010 Micro-Optics, Band: 7716, Seite: 77160K

2009

nach oben zur Jahresübersicht

I. Kallfass, A. Tessmann, H. Massler, A. Leuther, M. Schlechtweg, O. Ambacher
A 200 GHz active heterodyne receiver MMIC with low sub-harmonic LO power requirements for imaging frontends
2009 European Microwave Integrated Circuits Conference (EuMIC), Seiten: 45 - 48
I. Kallfass, A. Tessmann, H. Massler, D. Lopez-Diaz, A. Leuther, M. Schlechtweg, O. Ambacher
A 300 GHz active frequency-doubler and integrated resistive mixer MMIC
2009 European Microwave Integrated Circuits Conference (EuMIC), Seiten: 200 - 203
A. Tessmann, A. Leuther, V. Hurm, H. Massler, M. Zink, M. Kuri, M. Riessle, R. Losch, M. Schlechtweg, O. Ambacher
A 300 GHz mHEMT amplifier module
2009 IEEE International Conference on Indium Phosphide & Related Materials, Seiten: 169 - 199
Reiterer, A., Lehmann, M., Miljanovic, M., Ali, H., Paar, G., Egly, U., Eiter, T., Kahmen, H.
A 3D Optical Deformation Measurement System Supported by Knowledge-Based and Learning Techniques
2009 Journal of Applied Geodesy, Band: 3, Seiten: 1 - 13
S. Linkohr, S. U. Schwarz, S. Krischok, P. Lorenz, T. Nakamura, V. Polyakov, V. Cimalla, C. Nebell, O. Ambacher
A novel functionalization of AlGaN/GaN-pH-Sensors for DNA-sensors
2009 MRS Online Proceedings Library Archive, Band: 1202
Steinhauser M, Hiermaier S
A review of computational methods in materials science
2009 International journal of molecular sciences, Band: 10, Nummer: 12, Seiten: 5135 - 5216
KurzfassungThis review discusses several computational methods used on different length and time scales for the simulation of material behavior. First, the importance of physical modeling and its relation to computer simulation on multiscales is discussed. Then, computational methods used on different scales are shortly reviewed, before we focus on the molecular dynamics (MD) method. Here we survey in a tutorial-like fashion some key issues including several MD optimization techniques. Thereafter, computational examples for the capabilities of numerical simulations in materials research are discussed. We focus on recent results of shock wave simulations of a solid which are based on two different modeling approaches and we discuss their respective assets and drawbacks with a view to their application on multiscales. Then, the prospects of computer simulations on the molecular length scale using coarse-grained MD methods are covered by means of examples pertaining to complex topological polymer structures including star-polymers, biomacromolecules such as polyelectrolytes and polymers with intrinsic stiffness. This review ends by highlighting new emerging interdisciplinary applications of computational methods in the field of medical engineering where the application of concepts of polymer physics and of shock waves to biological systems holds a lot of promise for improving medical applications such as extracorporeal shock wave lithotripsy or tumor treatment.
Steinhauser, M.O., Hiermaier, S.
A review of computational methods in materials science : Examples from shock-wave and polymer physics
2009 International journal of molecular sciences, Band: 10, Seiten: 5135 - 5216
KurzfassungThis review discusses several computational methods used on different length and time scales for the simulation of material behavior. First, the importance of physical modeling and its relation to computer simulation on multiscales is discussed. Then, computational methods used on different scales are shortly reviewed, before we focus on the molecular dynamics (MD) method. Here we survey in a tutorial-like fashion some key issues including several MD optimization techniques. Thereafter, computational examples for the capabilities of numerical simulations in materials research are discussed. We focus on recent results of shock wave simulations of a solid which are based on two different modeling approaches and we discuss their respective assets and drawbacks with a view to their application on multiscales. Then, the prospects of computer simulations on the molecular length scale using coarse-grained MD methods are covered by means of examples pertaining to complex topological polymer structures including star-polymers, biomacromolecules such as polyelectrolytes and polymers with intrinsic stiffness. This review ends by highlighting new emerging interdisciplinary applications of computational methods in the field of medical engineering where the application of concepts of polymer physics and of shock waves to biological systems holds a lot of promise for improving medical applications such as extracorporeal shock wave lithotripsy or tumor treatment.
Bartsch J, Savio C, Hörteis M, Glunz Stefan
Achievements and challenges in two-step metallization processes for crystalline silicon solar cells
2009 Photovoltaics International, Band: 6, Seiten: 54 - 63
A. Hülsmann, A. Liebelt, A. Tessmann, A. Leuther, M. Schlechtweg, O. Ambacher
Active millimeter-wave imaging using a raster scanner
2009 Radar Sensor Technology XIII, Band: 7308
S. Chartier, A. Tessmann, A. Leuther, R. Weber, I. Kallfass, M. Schlechtweg, S. Stanko, H. Essen, O. Ambacher
Advanced mHEMT MMICs for 220 GHz high‐resolution imaging systems
2009 physica status solidi c, Band: 6, Nummer: 6, Seiten: 1390 - 1393
A. Hülsmann, A. Leuther, I. Kallfass, R. Weber, A. Tessmann, M. Schlechtweg, O. Ambacher
Advanced mHEMT technologies for space applications
2009 the Proceedings of the 20th International Symposium on Space Terahertz Technology, Seiten: 178 - 182
Veit D, Weidlich A, Krafft J
An agent-based analysis of the German electricity market with transmission capacity constraints
2009 Energy Policy, Band: 37, Nummer: 10, Seiten: 4132 - 4144
P. D. C. King, T. D. Veal, F. Fuchs, Ch. Y. Wang, D. J. Payne, A. Bourlange, H. Zhang, G. R. Bell, V. Cimalla, O. Ambacher, R. G. Egdell, F. Bechstedt, C. F. McConville
Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In2O3
2009 Phys Rev B, Band: 79, Nummer: 20, Seite: 205211
G. Pettinari, A. Polimeni, M. Capizzi, J. H. Blokland, P. C. M. Christianen, J. C. Maan, V. Lebedev, V. Cimalla, O. Ambacher
Carrier mass measurements in degenerate indium nitride
2009 Phys Rev B, Band: 79, Nummer: 16
Fritsch J, Hiermaier S, Strobl G
Characterizing and modeling the non-linear visco-elastoplastic tensile deformation properties of a glass fiber reinforced polypropylene
2009 , Seiten: 187 - 190
Fritsch J, Hiermaier S, Strobl G
Characterizing and modeling the non-linear viscoelastic tensile deformation of a glass fiber reinforced polypropylene
2009 , Seiten: 2460 - 2466
KurzfassungOn the basis of comprehensive experimental investigations on a long glass fiber reinforced polypropylene (PP-LGF) a novel rheological material model is developed. It features a decomposition of the stress into a time independent quasi-static and a time and strain dependent viscous contribution. Furthermore it allows for plastic deformations starting from the very beginning of straining and is thereby able to reproduce the absence of a purely linear elastic domain going along with the nonexistence of a defined yield point, characteristic for many fiber reinforced thermoplastic polymers. In order to approach the true quasi-static material behavior, various tensile tests were carried out. The viscous material behavior was deduced from a series of stress relaxation experiments and is described by Eyring’s equation with strain dependent viscosity parameters.
Goldschmidt J, Peters M, Hermle M, Glunz Stefan
Characterizing the light guiding of fluorescent concentrators
2009 Journal of Applied Physics, Band: 105, Nummer: 11
L. Kolaklieva, R. Kakanov, P. Stefanov, V. Cimalla, S. Maroldt, O. Ambacher, K. Tonisch, F. Niebelschütz
Composition and Interface Chemistry Dependence in Ohmic Contacts to GaN HEMT Structures on the Ti/Al Ratio and Annealing Conditions
2009 Materials Science Forum, Band: 615, Seiten: 951 - 954
Pysch D, Mette A, Filipovic A, Glunz Stefan
Comprehensive analysis of advanced solar cell contacts consisting of printed fine-line seed layers thickened by silver plating
2009 Progress in Photovoltaics: Research and Applications, Band: 17, Nummer: 2, Seiten: 101 - 114
J. Kuhn, F. Van Raay, R. Quay, R. Kiefer, D. Peschel, M. Mikulla, M. Seelmann-Eggebert, W. Bronner, M. Schlechtweg, O. Ambacher, M. Thumm
Design of X-band GaN MMICs using field plates
2009 European Microwave Integrated Circuits Conference (EuMIC), Seiten: 33 - 36
J. Kuhn, F. Van Raay, R. Quay, R. Kiefer, T. Maier, R. Stibal, M. Mikulla, M. Seelmann-Eggebert, W. Bronner, M. Schlechtweg, O. Ambacher, M. Thumm
Design of highly-efficient GaN X-band-power-amplifier MMICs
2009 IEEE MTT-S International Microwave Symposium Digest, Seiten: 661 - 664
F. M. Morales, D. González, J. G. Lozano, R. García, S. Hauguth-Frank, V. Lebedev, V. Cimalla, O. Ambacher
Determination of the composition of InxGa1− xN from strain measurements
2009 Acta Mater, Band: 57, Nummer: 19, Seiten: 5681 - 5692
Rosenits P, Roth T, Warta W, Reber S, Glunz Stefan
Determining the excess carrier lifetime in crystalline silicon thin-films by photoluminescence measurements
2009 Journal of Applied Physics, Band: 105, Nummer: 5
P. Waltereit, W. Bronner, R. Quay, M. Dammann, S. Müller, M. Musser, M. Mikulla, O. Ambacher, F. van Rijs, T. Rödle, K. Riepe
Development of AlGaN/GaN HEMTs with efficiencies above 60% up to 100 V for next generation mobile communication 100 W power bars
2009 physica status solidi c, Band: 6, Nummer: 6, Seiten: 1369 - 1372
Granek F, Hermle M, Huljić D, Schultz-Wittmann O, Glunz Stefan
Enhanced lateral current transport via the front N + diffused layer of n-type high-efficiency back-junction back-contact silicon solar cells
2009 Progress in Photovoltaics: Research and Applications, Band: 17, Nummer: 1, Seiten: 47 - 56
P. Waltereit, W. Bronner, R. Quay, M. Dammann, R. Kiefer, S. Müller, M. Musser, J. Kühn, F. van Raay, M. Seelmann-Eggebert, M. Mikulla, O. Ambacher, F. van Rijs, T. Rödle, K. Riepe
GaN HEMT and MMIC development at Fraunhofer IAF: performance and reliability
2009 physica status solidi (a), Band: 206, Nummer: 6, Seiten: 1215 - 1220
S. Maroldt, Ch. Haupt, W. Pletschen, S. Müller, R. Quay, O. Ambacher, Ch. Schippel, F. Schwierz
Gate-recessed AlGaN/GaN based enhancement-mode high electron mobility transistors for high frequency operation
2009 Jpn J Appl Phys, Band: 48, Nummer: 4S
S. Maroldt, C. Haupt, R. Kiefer, W. Bronner, S. Mueller, W. Benz, R. Quay, O. Ambacher
High efficiency digital GaN MMIC power amplifiers for future switch-mode based mobile communication systems
2009 Annual IEEE Compound Semiconductor Integrated Circuit Symposium, Seiten: 1 - 4
Roth T, Hohl-Ebinger J, Grote D, Schmich E, Warta W, Glunz Stefan, Sinton R
Illumination-induced errors associated with suns-V[sub OC] measurements of silicon solar cells
2009 Review of Scientific Instruments, Band: 80, Nummer: 3
P. Waltereit, S. Müller, K. Bellmann, C. Buchheim, R. Goldhahn, K. Köhler, L. Kirste, M. Baeumler, M. Dammann, W. Bronner, R. Quay, O. Ambacher
Impact of GaN cap thickness on optical, electrical, and device properties in AlGaN/GaN high electron mobility transistor structures
2009 J Appl Phys, Band: 106, Nummer: 2, Seite: 023535
R. E. Makon, R. Driad, R. Lösch, J. Rosenzweig, M. Schlechtweg, O. Ambacher
InP DHBT-based 1: 2 DEMUX IC operating at up to 120 Gbit/s
2009 Electron Lett, Band: 45, Nummer: 25, Seiten: 1340 - 1342
Goldschmidt J, Peters M, Bösch A, Helmers H, Dimroth F, Glunz Stefan, Willeke G
Increasing the efficiency of fluorescent concentrator systems
2009 Solar Energy Materials and Solar Cells, Band: 93, Nummer: 2, Seiten: 176 - 182
F. Balle, G. Wagner, D. Eifler
Joining of Aluminum 5754 Alloy to carbon fiber reinforced polymers (CFRP) by ultrasonic welding
2009 Aluminum Alloys, Band: II, Seiten: 191 - 196
A. Konkin, H.-K. Roth, P. Scharff, A. Aganov, O. Ambacher, S. Sensfuss
K-band ESR studies of structural anisotropy in P3HT and P3HT/PCBM blend polymer solid films: Paramagnetic defects after continuous wave Xe-lamp photolysis
2009 Solid State Commun, Band: 149, Nummer: 21-22, Seiten: 893 - 897
M. Schlechtweg, A. Tessmann, I. Kallfass, A. Leuther, R. Weber, S. Chartier, R. Driad, R. E. Makon, V. Hurm, M. Seelmann-Eggebert, H. Massler, M. Kuri, M. Riessle, M. Zink, F. Benkhelifa, R. Lösch, J. Rosenzweig, O. Ambacher
MMICs and mixed-signal ICs based on III/V technology for highest frequencies and data rates
2009 Frequenz, Band: 63, Nummer: 5-6, Seiten: 86 - 92
A. Leuther, A. Tessmann, I. Kallfass, R. Losch, M. Seelmann-Eggebert, N. Wadefalk, F. Schafer, J. D. Gallego Puyol, M. Schlechtweg, M. Mikulla, O. Ambacher
Metamorphic HEMT technology for low-noise applications
2009 IEEE International Conference on Indium Phosphide & Related Materials, Seiten: 188 - 191
I. Kallfass, A. Tessmann, A. Leuther, H. Massler, M. Schlechtweg, O. Ambacher
Millimeter-wave monolithic integrated circuits for imaging and remote sensing at 140, 200, and 300 GHz
2009 Millimetre Wave and Terahertz Sensors and Technology II, Band: 7485
S. Shokhovets, K. Köhler, O. Ambacher, G. Gobsch
Observation of Fermi-edge excitons and exciton-phonon complexes in the optical response of heavily doped n-type wurtzite GaN
2009 Phys Rev B, Band: 79, Nummer: 4, Seite: 045201
Hofmann M, Janz S, Schmidt C, Kambor S, Suwito D, Kohn N, Rentsch J, Preu R, Glunz Stefan
Recent developments in rear-surface passivation at Fraunhofer ISE
2009 Solar Energy Materials and Solar Cells, Band: 93, Nummer: 6-7, Seiten: 1074 - 1078
M. Dammann, M. Casar, P. Waltereit, W. Bronner, H. Konstanzer, R. Quay, S. Muller, M. Mikulla, O. Ambacher, P. Van der Wel, T. Rodle, R. Behtash, F. Bourgeois, K. Riepe
Reliability of AlGaN/GaN HEMTs under DC-and RF-operation
2009 Reliability of Compound Semiconductors Digest (ROCS), Seiten: 19 - 32
K. Brueckner, F. Niebelschuetz, K. Tonisch, R. Stephan, V. Cimalla, O. Ambacher, M. A. Hein
Resonant piezoelectric ALGaN/GaN MEMS sensors in longitudinal mode operation
2009 IEEE 22nd International Conference on Micro Electro Mechanical Systems, Seiten: 927 - 930
M. Gebinoga, I. Cimalla, L. Silveira, M. Klett, V. Lebedev, F. Niebelschütz, O. Ambacher, A. Schober
Response of nerve cell to inhibitor recorded by aluminium-gallium-nitride FET
2009 Sensors for environment, health and security, Seiten: 311 - 318
F. Niebelschütz, V. Cimalla, K. Brückner, R. Stephan, K. Tonisch, M. A. Hein, O. Ambacher
Sensing applications of micro-and nanoelectromechanical resonators
2009 Proceedings of the Institution of Mechanical Engineers, Part N: Journal of Nanoengineering and Nanosystems, Band: 221, Nummer: 2, Seiten: 59 - 65
Pysch D, Ziegler J, Becker J.-P., Suwito D, Janz S, Glunz Stefan, Hermle M
Stretched-exponential increase in the open-circuit voltage induced by thermal annealing of amorphous silicon-carbide heterojunction solar cells
2009 Applied Physics Letters, Band: 94, Nummer: 9
Benick J, Richter A, Hermle M, Glunz Stefan
Thermal stability of the Al 2 O 3 passivation on p-type silicon surfaces for solar cell applications
2009 physica status solidi (RRL) - Rapid Research Letters, Band: 3, Nummer: 7-8, Seiten: 233 - 235
Ch. Schilling, R. Ostendorf, G. Kaufel, R. Moritz, J. Wagner, O. Ambacher
Tunable GaAs-based high power tapered amplifiers in an external cavity setup
2009 CLEO/Europe-EQEC 2009-European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference
F. Balle, G. Wagner, D. Eifler
Ultraschallschweißen - Ein innovatives Fügeverfahren für hybride Leichtbaustrukturen aus Metall/CFK‐Verbunden
2009 Verbundwerkstoffe: 17. Symposium Verbundwerkstoffe und Werkstoffverbunde, Band: -, Seiten: 549 - 554
F. Balle, G. Wagner, D. Eifler
Ultrasonic metal welding of aluminium sheets to carbon fibre reinforced thermoplastic composites
2009 Adv Eng Mater, Band: 11, Seiten: 35 - 39
Ganzenmueller Georg, Patey G, Camp Philip
Vapour-liquid phase transition of dipolar particles
2009 4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND MOLECULAR PHYSICS, TAYLOR & FRANCIS LTD, Band: 107, Nummer: 4-6, Seiten: 403 - 413
KurzfassungThe question of whether a vapour-liquid phase transition exists in systems of particles with purely dipolar interactions is examined. New Monte Carlo simulation results are presented for the dipolar Yukawa hard sphere (DYHS) fluid with very small values of the attractive Yukawa well depth, almost two orders of magnitude smaller than the characteristic dipolar interaction energy. In this way, it is possible to approach the dipolar hard sphere (DHS) limit. It is found that phase separation is not observable beyond a critical value of the Yukawa energy parameter, even though in thermodynamic and structural terms, the DYHS and DHS systems are very similar. It is suggested that either some very subtle physics distinguishes the DYHS and DHS systems, or the observation of a phase transition in DHSs is precluded by finite-size effects.
Weidlich A, Vogt H, Karnouskos S
Wenn der Windpark mit der Waschmaschine redet
2009 Wirtschaftsinformatik und Management, Band: 1, Seiten: 30 - 34

2008

nach oben zur Jahresübersicht

J. Wagner, Ch. Y. Wang, C.-C. Röhlig, M. Maier, M. Kunzer, T. Passow, W. Schirmacher, W. Pletschen, V. Cimalla, K. Köhler, O. Ambacher
(AlGaIn) N UV LEDs for integrated metal-oxide based ozone sensors
2008 Light-Emitting Diodes: Research, Manufacturing, and Applications XII, Band: 6910
R. Ostendorf, G. Kaufel, R. Moritz, M. Mikulla, O. Ambacher, M. T. Kelemen, J. Gilly
10 W high-efficiency high-brightness tapered diode lasers at 976 nm
2008 High-Power Diode Laser Technology and Applications VI, Band: 6876
A. Leuther, A. Tessmann, H. Massler, R. Losch, M. Schlechtweg, M. Mikulla, O. Ambacher
35 nm metamorphic HEMT MMIC technology
2008 20th International Conference on Indium Phosphide and Related Materials, Seiten: 1 - 4
B. Lübbers, G. Kittler, P. Ort, S. Linkohr, D. Wegener, B. Baur, M. Gebinoga, F. Weise, M. Eickhoff, S. Maroldt, A. Schober, O. Ambacher
A novel GaN‐based multiparameter sensor system for biochemical analysis
2008 physica status solidi c, Band: 5, Nummer: 6, Seiten: 2361 - 2363
Hess, S, Rommel, M
Advanced Flat-plate Collectors' and 'Evacuated Tube Collectors
2008 Process Heat Collectors
Weidlich A, Veit D
Agent-based simulations for electricity market regulation advice: procedures and an example
2008 Jahrbücher für Nationalökonomie und Statistik, Band: 228, Nummer: 2+3, Seiten: 149 - 172
F. Niebelschütz, V. Cimalla, K. Tonisch, Ch. Haupt, K. Brückner, R. Stephan, M. Hein, O. Ambacher
AlGaN/GaN‐based MEMS with two‐dimensional electron gas for novel sensor applications
2008 physica status solidi c, Band: 5, Nummer: 6, Seiten: 1914 - 1916
Woehl R, Hörteis M, Glunz Stefan
Analysis of the Optical Properties of Screen-Printed and Aerosol-Printed and Plated Fingers of Silicon Solar Cells
2008 Advances in OptoElectronics, Band: 2008, Seiten: 1 - 7
Hermle M, Granek F, Schultz O, Glunz Stefan
Analyzing the effects of front-surface fields on back-junction silicon solar cells using the charge-collection probability and the reciprocity theorem
2008 Journal of Applied Physics, Band: 103, Nummer: 5
S. Shokhovets, O. Ambacher, B. K. Meyer, G. Gobsch
Anisotropy of the momentum matrix element, dichroism, and conduction-band dispersion relation of wurtzite semiconductors
2008 Phys Rev B, Band: 78, Nummer: 3
J. Kuhn, F. Van Raay, R. Quay, R. Kiefer, W. Bronner, M. Seelmann-Eggebert, M. Schlechtweg, M. Mikulla, O. Ambacher, M. Thumm
Balanced microstrip AlGaN/GaN HEMT power amplifier MMIC for X-band applications
2008 European Microwave Integrated Circuit Conference, Seiten: 95 - 98
P. Lorenz, V. Lebedev, F. Niebelschütz, S. Hauguth, O. Ambacher, J. A. Schaefer, S. Krischok
Characterization of GaN‐based lateral polarity heterostructures
2008 physica status solidi c, Band: 5, Nummer: 6, Seiten: 1965 - 1967
Ryan S, SchĂ¤fer F, Guyot M, Hiermaier S, Lambert M
Characterizing the transient response of CFRP/Al HC spacecraft structures induced by space debris impact at hypervelocity
2008 , Seiten: 1756 - 1763
KurzfassungTo quantify the disturbance induced by the impact of micrometeoroid and space debris particles at hypervelocity on vibration-sensitive CFRP/Al HC SP satellite platforms a method is presented which uses experimentally validated hydrocode models to characterize the impact-induced transient wave in the local structure. Key features of the transient waveform are simplified by a mathematical function which is expressed in terms of impactor momentum. Evolution of the transient waveform is characterized using multiple measurement gauges located on the sandwich panel facesheets outside the area of mechanical damage. The characterization is then used to extrapolate the elastic waveform back to the impact location. The elastic-equivalent excitation of a CFRP/Al HC SP is defined in terms of force with respect to time for application in finite element: structural codes for propagation of the local disturbance to vibration-sensitive locations (i.e. measurement devices).
U. Zhokhavets, H. Hoppe, G. Gobsch, Maher Al-Ibrahim, O. Ambacher, S. Voigt
Dynamical optical investigation of polymer/fullerene composite solar cells
2008 Phys Status Solidi B, Band: 245, Nummer: 4
R. Quay, F. van Raay, J. Kuhn, R. Kiefer, P. Waltereit, M. Zorcic, M. Musser, W. Bronner, M. Dammann, M. Seelmann-Eggebert, M. Schlechtweg, M. Mikulla, O. Ambacher, J. Thorpe, K. Riepe, F. van Rijs, M. Saad, L. Harm, T. Rodle
Efficient AlGaN/GaN HEMT Power Amplifiers
2008 European Microwave Integrated Circuit Conference, Seiten: 87 - 90
C. Buchheim, R. Goldhahn, G. Gobsch, K. Tonisch, V. Cimalla, F. Niebelschütz, O. Ambacher
Electric field distribution in GaN/AlGaN/GaN heterostructures with with two-dimensional electron and hole gas
2008 Appl Phys Lett, Band: 92, Nummer: 1
Ch. Y. Wang, V. Cimalla, Th. Kups, O. Ambacher, M. Himmerlich, S. Krischok
Electrical and optical properties of In2O3 nanoparticles prepared by MOCVD
2008 2nd IEEE International Nanoelectronics Conference, Seiten: 489 - 492
V. Lebedev, Ch. Y. Wang, S. Hauguth, V. Polyakov, F. Schwierz, V. Cimalla, T. Kups, F. M. Morales, J. G. Lozano, D. González, M. Himmerlich, J. A. Schaefer, S. Krischok, O. Ambacher
Electron transport properties of indium oxide–indium nitride metal‐oxide‐semiconductor heterostructures
2008 physica status solidi c, Band: 5, Nummer: 2, Seiten: 495 - 498
V. Lebedev, V. M. Polyakov, S. Hauguth-Frank, V. Cimalla, C. Y. Wang, G. Ecke, F. Schwierz, A. Schober, J. G. Lozano, F. M. Morales, D. González, O. Ambacher
Electronic and photoconductive properties of ultrathin InGaN photodetectors
2008 J Appl Phys, Band: 103, Nummer: 7
Roth T, Rüdiger M, Warta W, Glunz Stefan
Electronic properties of titanium in boron-doped silicon analyzed by temperature-dependent photoluminescence and injection-dependent photoconductance lifetime spectroscopy
2008 Journal of Applied Physics, Band: 104, Nummer: 7
I. Kallfass, A. Tessmann, A. Leuther, M. Kuri, M. Riessle, M. Zink, H. Massler, M. Schlechtweg, O. Ambacher
Enabling compact MMIC-based frontends for millimeter-wave imaging radar and radiometry at 94 and 210 GHz
2008 Millimetre Wave and Terahertz Sensors and Technology, Band: 7117
G. Pettinari, F. Masia, M. Capizzi, A. Polimeni, M. Losurdo, G. Bruno, T. H. Kim, S. Choi, A. Brown, V. Lebedev, V. Cimalla, O. Ambacher
Experimental evidence of different hydrogen donors in n-type InN
2008 Phys Rev B, Band: 77, Nummer: 12
Hörteis M, Glunz Stefan
Fine line printed silicon solar cells exceeding 20% efficiency
2008 Progress in Photovoltaics: Research and Applications, Band: 16, Nummer: 7, Seiten: 555 - 560
Ganzenmueller Georg, Pawlowski Grzegorz
Flat histogram Monte Carlo sampling for mechanical variables and conjugate thermodynamic fields with example applications to strongly correlated electronic systems
2008 ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA PHYSICAL REVIEW E, AMER PHYSICAL SOC, Band: 78, Nummer: 3, 2
KurzfassungWe present a general and unifying framework for deriving Monte Carlo acceptance rules which facilitate flat histogram sampling. The framework yields uniform sampling rules for thermodynamic states given by the mechanically extensive variables appearing in the Hamiltonian. Likewise, Monte Carlo schemes which uniformly sample the thermodynamic fields that are conjugate to the mechanical variables can be derived within this framework. We apply these different, yet equivalent sampling schemes to the extended Hubbard model in the atomic limit with explicit electron spin. Results for the full density-of-states, the charge-order parameter distribution, and phase diagrams for different ratios of the on-site Hubbard repulsion and the intersite interaction are presented. A tricritical point at half-filling of the lattice is located using finite-size scaling techniques.
F. Balle, S. Emrich, G. Wagner, D. Eifler
Fügen artfremder Werkstoffe - Ultraschallschweißen von Kohlenstofffasertextilien mit Metallen
2008 Materials Testing, Band: 50, Nummer: 4, Seiten: 184 - 189
Benick J, Hoex B, Schultz O, Glunz Stefan
High efficiency n-type Si solar cells on Al[sub 2]O[sub 3]-passivated boron emitters
2008 Applied Physics Letters, Band: 92, Nummer: 25
G. Matthäus, V. Cimalla, B. Pradarutti, S. Riehemann, G. Notni, V. Lebedev, O. Ambacher, S. Nolte, A. Tünnermann
Highly efficient THz emission from differently grown InN at 800 nm and 1060 nm excitation
2008 Opt Commun, Band: 281, Nummer: 14, Seiten: 3776 - 3780
Hiermaier S
Hydrocodes - Simulation tool of choice for transient processes
2008 , Seiten: 21 - 22
Wicklein M, Ryan S, White D, Clegg R
Hypervelocity impact on CFRP
2008 , Seiten: 1861 - 1869
KurzfassungThis paper describes the derivation and validation of a numerical material model that predicts the highly dynamic behaviour of CFRP (carbon fibre reinforced plastic) under hypervelocity impact. CFRP is widely used in satellites as face sheet material in CFRP-Al/HC sandwich structures (HC = honeycomb) that can be exposed to space debris. A review of CFRP-Al/HC structures typically used in space was performed. Based on this review, a representative structure in terms of materials and geometry was selected for study in the work described here. An experimental procedure for the characterisation of composite materials is documented by Riedel et al. [ADAMMO - advanced material damage models for numerical simulation codes. ESA CR(P) 4397, EMI report 175/03, Freiburg: October 31, 2003.]. The test results from the CFRP of the current study allow for the derivation of an experimentally based orthotropic continuum material model data set that is capable of predicting the mechanical behaviour of CFRP under hypervelocity impact. Such a data set was not previously available. In the work by Riedel et al. [Hypervelocity impact damage prediction in composites: part II - experimental investigations and simulations. International journal of Impact Engineering, 2006:33:670-80.] an orthotropic material data set was used for modelling HVI on AFRP (aramid fibre reinforced plastic), which shows relatively high deformability before failure. The enhancements of the modelling approaches in previous studies [Riedel W, Harwick W, White DM, Clegg RA. ADAMMO - advanced material damage models for numerical simulation codes. ESA CR(P) 4397, EMI report I 75/03, Freiburg: October 31, 2003. Hiermaier S, Riedel W, Hayhurst C, Clegg RA, Wentzel C. AMMHIS - advanced material models for hypervelocity impact simulations. Final report, EMI report E 43/98, ESA CR(P) 4305, Freiburg: July 30,1999.] necessary to model brittle CFRP are specified. An experimental hypervelocity impact campaign was performed at two different two-stage light gas guns which encompassed both normal and oblique impacts for a range of impact velocities and projectile diameters. Validation of the numerical model is provided through comparison with the experimental results. For that purpose measurements of the visible damage of the face sheets and of the HC core are conducted. In addition, the numerically predicted damage within the CFRP is compared to the delamination areas found in ultrasonic scans.
C. Y. Wang, V. Cimalla, V. Lebedev, T. Kups, G. Ecke, S. Hauguth, O. Ambacher, J. G. Lozano, F. M. Morales, D. Gonzalez
InN/In{sub 2}O{sub 3} heterostructures
2008 physica status solidi c, Band: 5, Nummer: 6
Rüdiger M, Trupke T, Würfel P, Roth T, Glunz Stefan
Influence of photon reabsorption on temperature dependent quasi-steady-state photoluminescence lifetime measurements on crystalline silicon
2008 Applied Physics Letters, Band: 92, Nummer: 22
S. Jebril, M. Elbahri, G. Titazu, K. Subannajui, S. Essa, F. Niebelschütz, C.‐Ch. Röhlig, V. Cimalla, O. Ambacher, B. Schmidt, D. Kabiraj, D. Avasti, R. Adelung
Integration of Thin‐Film‐Fracture‐Based Nanowires into Microchip Fabrication
2008 Small, Band: 4, Nummer: 12, Seiten: 2214 - 2221
F. Niebelschutz, J. Pezoldt, T. Stauden, V. Cimalla, K. Tonisch, K. Bruckner, M. Hein, O. Ambacher, A. Schober
Isotropic dry-etching of SiC for AlGaN/GaN MEMS fabrication
2008 Conference on Optoelectronic and Microelectronic Materials and Devices, Seiten: 26 - 29
Kray D, Fell A, Hopman S, Mayer K, Willeke G, Glunz Stefan
Laser chemical processing (LCP)—A versatile tool for microstructuring applications
2008 Applied Physics A Materials Science & Processing, Band: 93, Nummer: 1, Seiten: 99 - 103
Kalyuzhnyi Yu, Protsykevytch I, Ganzenmueller G, Camp P
Liquid-vapour coexistence in the dipolar Yukawa hard-sphere fluid
2008 6 RUE DES FRERES LUMIERE, MULHOUSE, 68200, FRANCE EPL, EPL ASSOCIATION, EUROPEAN PHYSICAL SOCIETY, Band: 84, Nummer: 2
KurzfassungThermodynamic perturbation theory for central-force associating potentials and Monte Carlo simulations are used to study the phase behaviour of the dipolar Yukawa hard-sphere fluid over a wide range of the particle dipole moment, mu. Liquid-vapour coexistence is found to exist for values of mu far in excess of a “threshold” value found in earlier simulation studies. The predictions of the present theory are found to be in reasonably good agreement with computer simulation results, all the way up to the highest dipole moment studied. Copyright (C) EPLA, 2008
A. Tessmann, I. Kallfass, A. Leuther, H. Massler, M. Kuri, M. Riessle, M. Zink, R. Sommer, A. Wahlen, H. Essen, V. Hurm, M. Schlechtweg, O. Ambacher
Metamorphic HEMT MMICs and modules for use in a high-bandwidth 210 GHz radar
2008 Ieee J Solid-st Circ, Band: 43, Nummer: 10, Seiten: 2194 - 2205
A. Tessmann, I. Kallfass, A. Leuther, H. Massler, M. Schlechtweg, O. Ambacher
Metamorphic MMICs for operation beyond 200 GHz
2008 European Microwave Integrated Circuit Conference, Seiten: 210 - 213
A. Konkin, F. Wendler, F. Meister, H.-K. Roth, A. Aganov, O. Ambacher
N-Methylmorpholine-N-oxide ring cleavage registration by ESR under heating conditions of the Lyocell process
2008 Spectrochim Acta A, Band: 69, Nummer: 3, Seiten: 1053 - 1055
Ch. Y. Wang, M. Ali, Th. Kups, C.-C. Röhlig, V. Cimalla, Th. Stauden, O. Ambacher
NOx sensing properties of In2O3 nanoparticles prepared by metal organic chemical vapor deposition
2008 Sensors and Actuators B: Chemical, Band: 130, Nummer: 2, Seiten: 589 - 593
M. Ali, Ch. Y. Wang, C.-C. Röhlig, V. Cimalla, Th. Stauden, O. Ambacher
NOx sensing properties of In2O3 thin films grown by MOCVD
2008 Sensor Actuat B-chem, Band: 129, Nummer: 1, Seiten: 467 - 472
V. Cimalla, C.-C. Röhlig, J. Pezoldt, M. Niebelschütz, O. Ambacher, K. Brückner, M. Hein, J. Weber, S. Milenkovic, A. J. Smith, A. W. Hassel
Nanomechanics of single crystalline tungsten nanowires
2008 J Nanomater, Band: 2008
Ahrens B, Löper P, Goldschmidt J, Glunz Stefan, Henke B, Miclea P.-T., Schweizer S
Neodymium-doped fluorochlorozirconate glasses as an upconversion model system for high efficiency solar cells
2008 physica status solidi (a), Band: 205, Nummer: 12, Seiten: 2822 - 2830
S. Hauguth, V. Lebedev, Ch. Mauder, F. Niebelschütz, H.‐J. Büchner, G. Jäger, O. Ambacher
Novel III‐nitride based transparent photodetectors for standing wave interferometry
2008 Phys Status Solidi A, Band: 205, Nummer: 8, Seiten: 2080 - 2084
Hiermaier S, Gebbeken N
Numerical methods for dynamic processes
2008 , Seiten: 17 - 18
G. Ecke, Ch. Y Wang, V. Cimalla, O. Ambacher
Ozone and UV assisted oxidation of InN surfaces
2008 physica status solidi c, Band: 5, Nummer: 6, Seiten: 1603 - 1605
Hofmann M, Kambor S, Schmidt C, Grambole D, Rentsch J, Glunz Stefan, Preu R
PECVD-ONO: A new deposited firing stable rear surface passivation layer system for crystalline silicon solar cells
2008 Advances in OptoElectronics, Band: 2008, Seiten: 1 - 10
Ch. Wang, Y. Dai, J. Pezoldt, B. Lu, Th. Kups, V. Cimalla, O. Ambacher
Phase stabilization and phonon properties of single crystalline rhombohedral indium oxide
2008 Cryst Growth Des, Band: 8, Nummer: 4, Seiten: 1257 - 1260
K. Tonisch, C. Buchheim, F. Niebelschütz, A. Schober, G. Gobsch, V. Cimalla, O. Ambacher, R. Goldhahn
Piezoelectric actuation of (GaN/) AlGaN/GaN heterostructures
2008 J Appl Phys, Band: 104, Nummer: 8
K. Tonisch, C. Buchheim, F. Niebelschütz, M. Donahue, R. Goldhahn, V. Cimalla, O. Ambacher
Piezoelectric actuation of all‐nitride MEMS
2008 physica status solidi c, Band: 5, Nummer: 6, Seiten: 1910 - 1913
O. Ambacher, V. Cimalla
Polarization induced effects in GaN-based heterostructures and novel sensors
2008 Polarization Effects in Semiconductors, Seiten: 27 - 109
Heide D, Schäfer M, Greiner M
Robustness of networks against fluctuation-induced cascading failures.
2008 Phys Rev E, Band: 77, Nummer: 5 Pt 2, Seiten: 056103 - 056103
KurzfassungFluctuating fluxes on a complex network lead to load fluctuations at the vertices, which may cause them to become overloaded and to induce a cascading failure. A characterization of the one-point load fluctuations is presented, revealing their dependence on the nature of the flux fluctuations and on the underlying network structure. Based on these findings, an alternate robustness layout of the network is proposed. Taking load correlations between the vertices into account, an analytical prediction of the probability for the network to remain fully efficient is confirmed by simulations. Compared to previously proposed mean-flux layouts, the alternate layout comes with significantly less investment costs in the high-confidence limit.
M. Hofmann, S. Hauguth-Frank, V. Lebedev, O. Ambacher, S. Sinzinger
Sapphire-GaN-based planar integrated free-space optical system
2008 Appl Optics, Band: 47, Nummer: 16, Seiten: 2950 - 2955
M. Niebelschütz, V. Cimalla, O. Ambacher, T. Machleidt, K.‐H. Franke, J. Ristic, J. Grandal, M. A. Sánchez‐García, E. Calleja
Space charged region in GaN and InN nanocolumns investigated by atomic force microscopy
2008 physica status solidi c, Band: 5, Nummer: 6, Seiten: 1609 - 1611
Hofmann M, Schmidt C, Kohn N, Rentsch J, Glunz Stefan, Preu R
Stack system of PECVD amorphous silicon and PECVD silicon oxide for silicon solar cell rear side passivation
2008 Progress in Photovoltaics: Research and Applications, Band: 16, Nummer: 6, Seiten: 509 - 518
S. Hauguth-Frank, V. Lebedev, K. Tonisch, H. Romanus, Th. Kups, H.-J. Büchner, G. Jäger, O. Ambacher, A. Schober
Structural and photoconducting properties of MBE and MOCVD grown III-nitride double-heterostructures
2008 MRS Online Proceedings Library Archive, Band: 1076
Vergniaud J, Guyot M, Lambert M, SchĂ¤fer F, Ryan S, Hiermaier S, Taylor E
Structural vibrations induced by HVI - Application to the Gaia spacecraft
2008 , Seiten: 1836 - 1843
KurzfassungGiven the growing stability needed for spacecraft in operation to ensure functioning of future instruments whose sensitivity requires an important technological step, perturbations encounter in orbital conditions that used to be negligible, become today an issue. This is the case of micrometeorite impacts whose energy could induce modal response of the flexible structure and imply a dynamic response of the spacecraft which could probably be disturbing for the instrument functioning. The impact environment that could be encountered by the spacecraft is preliminary studied before the definition of test to recreate the excitation with light-gas gun. Experiments are made on samples of structure representative of the ongoing Gaia astrometric mission project. Response of the structure is recorded to be correlated to finite elements model of the sample. The excitation is then extrapolated to orbital conditions and to Gaia finite elements model. The final perturbation is compared to the specification. The main conclusion is that for daily impact event, dynamic response of the structure will not disturb Gaia functioning. Nevertheless, for a yearly impact event, the astrometric mission will largely be disturbed by the dynamic response of the structure to the impact.
F. M. Morales, J. G. Lozano, R. García, V. Lebedev, Ch. Y. Wang, V. Cimalla, O. Ambacher, D. González
Structure of cubic polytype indium nitride layers on top of modified sapphire substrates
2008 physica status solidi c, Band: 5, Nummer: 2, Seiten: 514 - 517
F. M. Morales, J. G. Lozano, R. García, V. Lebedev, S. Hauguth-Frank, V. Cimalla, O. Ambacher, D. González
Study of microstructure and strain relaxation on thin InXGa1−xN epilayers with medium and high In contents
2008 14th European Microscopy Congress, Seiten: 77 - 78
A. Konkin, S. Sensfuss, H.-K. Roth, P. Scharff, O. Ambacher
TRESR study of the photo-induced electron transfer in P3DDT/maleic anhydride blend in THF solution under UV flash photolysis
2008 J Mol Liq, Band: 141, Nummer: 1-2, Seiten: 54 - 61
L Kolaklieva, R Kakanakov, V Cimalla, F Niebelschutz, K Tonisch, O Ambacher
The role of Ti/A1 ratio in nanolayered ohmic contacts for GaN/AlGaN HEMTs
2008 26th International Conference on Microelectronics, Seiten: 221 - 224
Goldschmidt J, Peters M, Prönneke L, Steidl L, Zentel R, Bläsi B, Gombert A, Glunz Stefan, Willeke G, Rau U
Theoretical and experimental analysis of photonic structures for fluorescent concentrators with increased efficiencies
2008 physica status solidi (a), Band: 205, Nummer: 12, Seiten: 2811 - 2821
Kray D, Hermle M, Glunz Stefan
Theory and experiments on the back side reflectance of silicon wafer solar cells
2008 Progress in Photovoltaics: Research and Applications, Band: 16, Nummer: 1, Seiten: 1 - 15
Schultz O, Mette A, Hermle M, Glunz Stefan
Thermal oxidation for crystalline silicon solar cells exceeding 19% efficiency applying industrially feasible process technology
2008 Progress in Photovoltaics: Research and Applications, Band: 16, Nummer: 4, Seiten: 317 - 324
K. Brueckner, F. Niebelschuetz, K. Tonisch, S. Michael, A. Dadgar, A. Krost, V. Cimalla, O. Ambacher, R. Stephan, M. A. Hein
Two-dimensional electron gas based actuation of piezoelectric AlGaN/GaN microelectromechanical resonators
2008 Appl Phys Lett, Band: 93, Nummer: 17
S. Hauguth‐Frank, V. Lebedev, H.‐J. Büchner, G. Jäger, O. Ambacher
Ultra‐thin InGaN photodetectors for standing wave interferometry
2008 physica status solidi c, Band: 5, Nummer: 6, Seiten: 2117 - 2119
Goldschmidt J, Peters M, Dimroth F, Glunz Stefan
Zurück in die Zukunft - Mit neuen Konzepten erlebt eine alte Konzentratortechnologie ihre Renaissance
2008 Erneuerbare Energien, Band: Nov 2008, Seiten: 48 - 52

2007

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Pysch D, Mette A, Glunz Stefan
A review and comparison of different methods to determine the series resistance of solar cells
2007 Solar Energy Materials and Solar Cells, Band: 91, Nummer: 18, Seiten: 1698 - 1706
I. Cimalla, F. Will, K. Tonisch, M. Niebelschütz, V. Cimalla, V. Lebedev, G. Kittler, M. Himmerlich, S. Krischok, J. A. Schaefer, M. Gebinoga, A. Schober, Th. Friedrich, O. Ambacher
AlGaN/GaN biosensor—effect of device processing steps on the surface properties and biocompatibility
2007 Sensor Actuat B-chem, Band: 123, Nummer: 2, Seiten: 740 - 748
V. Cimalla, T. Machleidt, L. Spieß, M. Gubisch, I. Hotovy, H. Romanus, O. Ambacher
Analysis of nanocrystalline films on rough substrates
2007 Ultramicroscopy, Band: 107, Nummer: 10-11, Seiten: 989 - 994
G. Ecke, V. Cimalla, K. Tonisch, V. Lebedev, H. Romanus, O. Ambacher, J. Liday
Analysis of nanostructures by means of Auger electron spectroscopy
2007 Journal of Electrical Engineering, Band: 58, Nummer: 6
Ganzenmueller Georg, Camp Philip
Applications of Wang-Landau sampling to determine phase equilibria in complex fluids
2007 CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA JOURNAL OF CHEMICAL PHYSICS, AMER INST PHYSICS, Band: 127, Nummer: 15
KurzfassungApplications of the Wang-Landau algorithm for simulating phase coexistence at fixed temperature are presented. The number density is sampled using either volume scaling or particle insertion/deletion. The resulting algorithms, while being conceptually easy, are of comparable efficiency to existing multicanonical methods but with the advantage that neither the chemical potential nor the pressure at phase coexistence has to be estimated in advance of the simulation. First, we benchmark the algorithm against literature results for the vapor-liquid transition in the Lennard-Jones fluid. We then demonstrate the general applicability of the algorithm by studying vapor-liquid coexistence in two examples of complex fluids: charged soft spheres, which exhibit a transition similar to that in the restricted primitive model of ionic fluids, being characterized by strong ion pairing in the vapor phase; and Stockmayer fluids with high dipole strengths, in which the constituent particles aggregate to form chains, and for which the very existence of a transition has been widely debated. Finally, we show that the algorithm can be used to locate a weak isotropic-nematic transition in a fluid of Gay-Berne mesogens. (C) 2007 American Institute of Physics.
V. Lebedev, D. Cengher, K. Tonisch, F. Will, I. Cimalla, Ch. Mauder, S. Hauguth, O. Ambacher, F. M. Morales, J. G. Lozano, D. González
Coalescence aspects of III-nitride epitaxy
2007 J Appl Phys, Band: 101, Nummer: 5
Diez S, Rein S, Roth T, Glunz Stefan
Cobalt related defect levels in silicon analyzed by temperature- and injection-dependent lifetime spectroscopy
2007 Journal of Applied Physics, Band: 101, Nummer: 3
S. Shokhovets, O. Ambacher, G. Gobsch
Conduction-band dispersion relation and electron effective mass in III-V and II-VI zinc-blende semiconductors
2007 Phys Rev B, Band: 76, Nummer: 12
J. G. Lozano, F. M. Morales, R. García, D. González, V. Lebedev, Ch. Y. Wang, V. Cimalla, O. Ambacher
Cubic InN growth on sapphire (0001) using cubic indium oxide as buffer layer
2007 Appl Phys Lett, Band: 90, Nummer: 9
A. Konkin, F. Wendler, F. Meister, H.-K. Roth, A. Aganov, O. Ambacher
Degradation processes in the cellulose/N-methylmorpholine-N-oxide system studied by HPLC and ESR. Radical formation/recombination kinetics under UV photolysis at 77 K
2007 Cellulose, Band: 14, Nummer: 5
Rosenits P, Roth T, Glunz Stefan, Beljakowa S
Determining the defect parameters of the deep aluminum-related defect center in silicon
2007 Applied Physics Letters, Band: 91, Nummer: 12
P. Schley, R. Goldhahn, A. T. Winzer, G. Gobsch, V. Cimalla, O. Ambacher, H. Lu, W. J. Schaff, M. Kurouchi, Y. Nanishi, M. Rakel, C. Cobet, N. Esser
Dielectric function and Van Hove singularities for In-rich InxGa1−xN alloys: Comparison of N- and metal-face materials
2007 Phys Rev B, Band: 75, Nummer: 20
Würfel P, Trupke T, Puzzer T, Schäffer E, Warta W, Glunz Stefan
Diffusion lengths of silicon solar cells from luminescence images
2007 Journal of Applied Physics, Band: 101, Nummer: 12
V. Lebedev, V. Cimalla, F. M. Morales, J.G. Lozano, D. Gonzalez, Ch. Mauder, O. Ambacher
Effect of island coalescence on structural and electrical properties of InN thin films
2007 J Cryst Growth, Band: 300, Nummer: 1, Seiten: 50 - 56
V. Lebedev, Ch. Y. Wang, V. Cimalla, S. Hauguth, T. Kups, M. Ali, G. Ecke, M. Himmerlich, S. Krischok, J. A. Schaefer, O. Ambacher, V. M. Polyakov, F. Schwierz
Effect of surface oxidation on electron transport in InN thin films
2007 J Appl Phys, Band: 101, Nummer: 12
M. Niebelschütz, V. Cimalla, O. Ambacher, T. Machleidt, J. Ristic, E. Calleja
Electrical performance of gallium nitride nanocolumns
2007 Physica E, Band: 37, Nummer: 1-2, Seiten: 200 - 203
M. Niebelschütz, V. Cimalla, O. Ambacher, T. Machleidt, K. H. Franke, J. Ristic, J. Grandal, M. A. Sánchez-García, E. Calleja
Electrically characterization of Group III-Nitride nanocolumns with Scanning Force Microscopy
2007 Modern Research and Educational Topics in Microscopy
Roth T, Rosenits P, Diez S, Glunz Stefan, Macdonald D, Beljakowa S, Pensl G
Electronic properties and dopant pairing behavior of manganese in boron-doped silicon
2007 Journal of Applied Physics, Band: 102, Nummer: 10
J. G. Lozano, F. M. Morales, R. García, V. Lebedev, V. Cimalla, O. Ambacher, D. González
Evaluation of the influence of GaN and AlN as pseudosubstrates on the crystalline quality of InN layers
2007 physica status solidi c, Band: 4, Nummer: 4, Seiten: 1454 - 1457
E. Calleja, J. Grandal, M. A. Sanchez-Garcia, M. Niebelschütz, V. Cimalla, O. Ambacher
Evidence of electron accumulation at nonpolar surfaces of InN nanocolumns
2007 Appl Phys Lett, Band: 90, Nummer: 26
Huberth F, Hiermaier S
Experimental parameter identification for material models including deformation induced volume dilation for thermoplastic materials
2007 , Seiten: 293 - 294
KurzfassungSimulation of structures made from thermoplastic materials under crash loads including large deformations and failure is still a challenge for most existing numerical tools. To model the complex mechanical behaviour of thermoplastic materials new models have been developed. To reproduce the mechanical behaviour in the simulation, model parameters for each material have to be identified by experimental testing.
J. Pezoldt, Ch. Förster, V. Cimalla, F. Will, R. Stephan, K. Brückner, M. Hein, O. Ambacher
FTIR ellipsometry analysis of the internal stress in SiC/Si MEMS
2007 Materials science forum, Band: 556, Seiten: 363 - 366
V. Lebedev, D. Cengher, M. Fischer, K. Tonisch, V. Cimalla, M. Niebelschütz, O. Ambacher
Fabrication of one‐dimensional “trenched” GaN nanowires and their interconnections
2007 Phys Status Solidi A, Band: 204, Nummer: 10, Seiten: 3387 - 3391
A. Somogyi, G. Martinez-Criado, A. Homs, M. A. Hernandez-Fenollosa, D. Vantelon, O. Ambacher
Formation of Si clusters in AlGaN: A study of local structure
2007 Appl Phys Lett, Band: 90, Nummer: 18
K. Tonisch, V. Cimalla, F. Niebelschütz, H. Romanus, M. Eickhoff, O. Ambacher
Fully unstrained GaN on sacrificial AlN layers by nano‐heteroepitaxy
2007 physica status solidi c, Band: 4, Nummer: 7, Seiten: 2248 - 2251
K. Bruckner, V. Cimalla, F. Niebelschutz, R. Stephan, K. Tonisch, O. Ambacher, M. A. Hein
Gas pressure sensing based on MEMS resonators
2007 SENSORS, 2007 IEEE, Seiten: 1251 - 1254
V. Cimalla, J. Pezoldt, O. Ambacher
Group III nitride and SiC based MEMS and NEMS: materials properties, technology and applications
2007 J Phys D Appl Phys, Band: 40, Nummer: 20
K. Tonisch, F. Weise, M. Stubenrauch, V. Cimalla, G. Ecke, F. Will, H. Romanus, S. Mrotzek, H. Hofmeister, M. Hoffmann, D. Hülsenberg, O. Ambacher
Growth of silicon nanowires on UV-structurable glass using self-organized nucleation centres
2007 Physica E, Band: 38, Nummer: 1-2, Seiten: 40 - 43
V. Cimalla, B. Pradarutti, G. Matthäus, C. Brückner, S. Riehemann, G. Notnu, S. Nolte, A. Tünnermann, V. Lebedev, O. Ambacher
High efficient terahertz emission from InN surfaces
2007 Phys Status Solidi B, Band: 244, Nummer: 6, Seiten: 1829 - 1833
Glunz Stefan
High-efficiency crystalline silicon solar cells
2007 Advances in OptoElectronics, Band: 2007, Nummer: 10, Seiten: 1 - 15
Ch. Y. Wang, V. Cimalla, Th. Kups, C.-C. Röhlig, Th. Stauden, O. Ambacher, M. Kunzer, T. Passow, W. Schirmacher, W. Pletschen, K. Köhler, J. Wagner
Integration of In2O3 nanoparticle based ozone sensors with GaInN/GaN light emitting diodes
2007 Appl Phys Lett, Band: 91, Nummer: 10
Reiterer, A.
Intelligente Steuerung geodätischer Sensoren
2007 Österreichische Zeitschrift für Vermessung und Geoinformation (VGI), Band: Nr. 95, Seiten: 294 - 301
H. Romanus, J. Schadewald, V. Cimalla, M. Niebelschütz, T. Machleidt, K.-H. Franke, L. Spiess, O. Ambacher
Markers prepared by focus ion beam technique for nanopositioning procedures
2007 Microelectron Eng, Band: 84, Nummer: 3, Seiten: 524 - 527
Mingirulli N, Biro D, Preu R, Glunz Stefan, Riepe S
Method for determination of recombination activity of cylindric conduction channels for back-contacted solar cells
2007 Applied Physics Letters, Band: 91, Nummer: 18
J. Pezoldt, Ch. Förster, Th. Stauden, V. Cimalla, F. M. Morales, C. Zgheib, P. Masri, O. Ambacher
Morphology and Stress Control in UHVCVD of 3C-SiC (100) on Si
2007 Materials science forum, Band: 556, Seiten: 203 - 206
M. Himmerlich, S. Krischok, V. Lebedev, O. Ambacher, J. A. Schaefer
Morphology and surface electronic structure of MBE grown InN
2007 J Cryst Growth, Band: 306, Nummer: 1, Seiten: 6 - 11
V. Cimalla, F. Niebelschütz, K. Tonisch, Ch. Förster, K. Brückner, I. Cimalla, T. Friedrich, J. Pezoldt, R. Stephan, M. Hein, O. Ambacher
Nanoelectromechanical devices for sensing applications
2007 Sensor Actuat B-chem, Band: 126, Nummer: 1, Seiten: 24 - 34
V. Cimalla, K. Brückner, A. W. Hassel, M. A. Hein, F. Niebelschütz, M. Niebelschütz, J. von Pezoldt, H. Romanus, C. C. Röhlig, K. Tonisch, J. Weber, O. Ambacher
Nanomechanics with nanowires and nano-electro-mechanical systems
2007 Workshop Development, characterization and industrial application of nanostructured thin films, hard and superhard coatings
K. Tonisch, V. Cimalla, F. Will, F. Weise, M. Stubenrauch, A. Albrecht, M. Hoffmann, O. Ambacher
Nanowire-based electromechanical biomimetic sensor
2007 Physica E, Band: 37, Nummer: 1-2, Seiten: 208 - 211
P. Lorenz, V. Lebedev, R. Gutt, J. A Schaefer, O. Ambacher, St. Krischok
Oxidation of lateral polarity heterostructure GaN
2007 Verhandlungen der Deutschen Physikalischen Gesellschaft, Band: 42
Ch. Y. Wang, V. Cimalla, T. Kups, C. Röhlig, H. Romanus, V. Lebedev, J. Pezoldt, T. Stauden, O. Ambacher
Photoreduction and oxidation behavior of In2O3 nanoparticles by metal organic chemical vapor deposition
2007 J Appl Phys, Band: 102, Nummer: 4
H. Romanus, J. Schadewald, V. Cimalla, M. Niebelschütz, T. Machleidt, K.-H. Franke, L. Spiess, O. Ambacher
Preparation of defined structures on very thin foils for characterization of AFM probes
2007 Microelectron Eng, Band: 84, Nummer: 3, Seiten: 528 - 531
M. Ali, V. Cimalla, V. Lebedev, T. Stauden, C. Wang, G. Ecke, V. Tilak, P. Sandvik, O. Ambacher
Reactively sputtered InxVyOz films for detection of NOx, D2, and O2
2007 Sensor Actuat B-chem, Band: 123, Nummer: 2, Seiten: 779 - 783
V. Cimalla, V. Lebedev, Ch. Y. Wang, M. Ali, G. Ecke, V. M. Polyakov, F. Schwierz, O. Ambacher, H. Lu, W. J. Schaff
Reduced surface electron accumulation at InN films by ozone induced oxidation
2007 Appl Phys Lett, Band: 90, Nummer: 15
Mette A, Pysch D, Emanuel G, Erath D, Preu R, Glunz Stefan
Series resistance characterization of industrial silicon solar cells with screen-printed contacts using hotmelt paste
2007 Progress in Photovoltaics: Research and Applications, Band: 15, Nummer: 6, Seiten: 493 - 505
M. Ali, V. Cimalla, V. Lebedev, Th. Stauden, G. Ecke, V. Tilak, P. Sandvik, O. Ambacher
SiC-based FET for detection of NOx and O2 using InSnOx as a gate material
2007 Sensor Actuat B-chem, Band: 122, Nummer: 1, Seiten: 182 - 186
V. Lebedev, G. Cherkashinin, G. Ecke, I. Cimalla, O. Ambacher
Space charge limited electron transport in AlGaN photoconductors
2007 J Appl Phys, Band: 101, Nummer: 3
R. Schwarz, R. Cabeja, E. Morgado, M. Niehus, O. Ambacher, C. P. Marques, E. Alves
Stability of GaN films under intense MeV He ion irradiation
2007 Diamond and related materials, Band: 16, Nummer: 4-7, Seiten: 1437 - 1440
K. Brückner, V. Cimalla, F. Niebelschütz, R. Stephan, K. Tonisch, O. Ambacher, M. A. Hein
Strain-and pressure-dependent RF response of microelectromechanical resonators for sensing applications
2007 J Micromech Microeng, Band: 17, Nummer: 10
Ch. Wang, V. Lebedev, V. Cimalla, Th. Kups, K. Tonisch, O. Ambacher
Structural studies of single crystalline In2O3 films epitaxially grown on InN(001)
2007 Appl Phys Lett, Band: 90, Nummer: 22
M. Himmerlich, Ch. Wang, V. Cimalla, J. A Schaefer, O. Ambacher, St. Krischok
Surface properties of indium oxide and its interaction with ozone for the use as gas sensor
2007 Verhandlungen der Deutschen Physikalischen Gesellschaft, Band: 42, Nummer: 4
V. Cimalla, M. Stubenrauch, F. Weise, M. Fischer, K. Tonisch, M. Hoffmann, O. Ambacher
Suspended nanowire web
2007 Appl Phys Lett, Band: 90, Nummer: 10
Th. Kups, Ch. Wang, M. Gubisch, L. Spiess, O. Ambacher
TEM investigation of sputtered and epitaxial grown indium oxide layers for ozone sensors
2007 Microsc Microanal, Band: 13, Nummer: 406
Reiterer, A.
The Development of an Online Knowledge-Based Videotheodolite Measurement System
2007 Knowledge-Based Systems Journal, Elsevier, Band: 20, Nummer: 1, Seiten: 73 - 85
Palmer Michael, Ganzenmueller Georg, Walker Isobel
The electronic states of oxazole studied by VUV absorption and electron energy-loss (EEL) spectroscopies, and ab initio configuration interaction methods
2007 PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS CHEMICAL PHYSICS, ELSEVIER SCIENCE BV, Band: 334, Nummer: 1-3, Seiten: 154 - 166
KurzfassungThe oxazole VUV absorption spectrum over the range 5-12 eV shows intense bands centred near 6.3, 7.5, 8.3, 9.6 and 10.8 eV. The electron energy-loss (EEL) spectrum shows additional structure with a strong peak (similar to 1.4 eV) arising from resonant vibrational excitation of the molecule via a shape resonance, and a spin-forbidden (3)pi pi* state at 4.6 eV. Electronic excitation energies for valence and Rydberg-type states have been computed using ab initio multi-reference multi-root CI methods. The CI studies used a triple zeta + polarisation basis set, augmented by diffuse (Rydberg) orbitals, to generate the theoretical singlet and triplet energy manifolds. The correlation of theory and experiment shows the nature of the more intense Rydberg state types, and identification of the main valence and Rydberg bands. Calculated energies for low-lying Rydberg states are relatively close (SD 0.38) to those expected, and there is generally a good correlation between the theoretical and experimental envelopes. Two of the three lowest electronic states arise from pi pi* excitation of the outer (3a” and 2a”) pi-orbitals, with one state (LPN pi*) originating from the lone pair on nitrogen (15a’) between them. (c) 2007 Elsevier B.V. All rights reserved.
Ch. Wang, V. Cimalla, G. Cherkashinin, H. Romanus, M. Ali, O. Ambacher
Transparent conducting indium oxide thin films grown by low-temperature metal organic chemical vapor deposition
2007 Thin Solid Films, Band: 515, Nummer: 5, Seiten: 2921 - 2925
Ch. Y. Wang, V. Cimalla, H. Romanus, Th. Kups, M. Niebelschütz, O. Ambacher
Tuning of electrical and structural properties of indium oxide films grown by metal organic chemical vapor deposition
2007 Thin Solid Films, Band: 515, Nummer: 16, Seiten: 6611 - 6614
F. Balle, G. Wagner, D. Eifler
Ultrasonic spot welding of aluminum sheet/carbon fiber reinforced polymer–joints
2007 Materialwiss Werkst, Band: 38, Nummer: 11, Seiten: 934 - 938
T. Machleidt, K.-H. Franke, H. Romanus, V. Cimalla, M. Niebelschütz, L. Spieß, O. Ambacher
Using defined structures on very thin foils for characterizing AFM tips
2007 Ultramicroscopy, Band: 107, Nummer: 10-11, Seiten: 1086 - 1090
Ganzenmuller Georg, Camp Philip
Vapor-liquid coexistence in fluids of charged hard dumbbells
2007 CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA JOURNAL OF CHEMICAL PHYSICS, AMER INST PHYSICS, Band: 126, Nummer: 19
KurzfassungVapor-liquid coexistence in fluids of charged hard dumbbells, each made up of two oppositely charged hard spheres with diameters sigma and separation d, has been studied using grand-canonical Monte Carlo simulations. In the limit d/sigma -> 0, and with the temperature scaled accordingly, the system corresponds to dipolar hard spheres. For separations in the range 0.3 < d/sigma <= 1 the coexisting vapor phase contains compact clusters. For separations in the range 0.1 <= d/sigma < 0.3 the coexistence is between a chainlike vapor and a networklike liquid. Finite-size effects preclude the simulation of the coexistence in systems with d/sigma < 0.1, but extrapolations of the results to d/sigma -> 0 yield estimates of the apparent critical parameters for dipolar hard spheres. (C) 2007 American Institute of Physics.
Hiermaier S, Wicklein M
Zellulare Werkstoffe in der Crashsimulation
2007

2006

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S. Sokovets, G. Gobsch, V. Lebedev, O. Ambacher
'Anomalous' pseudodielectric function of GaN: Experiment, modelling and application to the study of surface properties
2006 Appl Surf Sci, Band: 253, Nummer: 1, Seiten: 224 - 227
Ch. Y. Wang, V. Cimalla, C.-C. Roehlig, Th. Stauden, F. Niebelschuetz, O. Ambacher, O. Kiesewetter, S. Kittelmann
A new type of highly sensitive portable ozone sensor operating at room temperature
2006 SENSORS, IEEE, Seiten: 81 - 84
M. Ali, V. Cimalla, V. Lebedev, V. Tilak, P. M. Sandvik, D. W. Merfeld, O. Ambacher
A study of hydrogen sensing performance of Pt–GaN Schottky diodes
2006 Ieee Sens J, Band: 6, Nummer: 5, Seiten: 1115 - 1119
T. Erb, U. Zhokhavets, H. Hoppe, G. Gobsch, M. Al-Ibrahim, O. Ambacher
Absorption and crystallinity of poly (3-hexylthiophene)/fullerene blends in dependence on annealing temperature
2006 Thin Solid Films, Band: 511, Seiten: 483 - 485
Ryan S, SchĂ¤fer F, Spencer G, Hiermaier S, Guyot M, Lambert M
An excitation function for hypervelocity impact-induced wave propagation in satellite structures
2006 , Seiten: 3838 - 3846
KurzfassungAn empirical excitation function which defines the elastic excitation of a satellite wall-representative Aluminum plate from impact of a projectile at hypervelocity is derived empirically from experimentally validated hydrocode simulations. The resulting function is intended for application in a structural finite element model code to assess the perturbation effects of small micrometeoroid and space debris impacts on highly stiffened satellite structures. This will enable the risk that these impacts pose on a future generation of ESA scientific satellite missions employing ultra-sensitive equipment to be quantified. The excitation function has been empirically derived from simulated velocity measurements made at various offsets from the impact location. The measured velocity waveforms have been simplified in terms of its frequency content in mind of its end-point application in structural codes, and this simplified velocity waveform has been extrapolated to the impact o rigin. The resulting empirical function is polynomial-exponential decay in form, and defines a point-source velocity-time input for structural codes.
J. Pezoldt, Th. Kups, P. Weih, Th. Stauden, O. Ambacher
Atomic Layer Epitaxy of (Si1-xC1-y) Gex+ y Layers on 4H-SiC
2006 Materials science forum, Band: 527, Seiten: 1559 - 1562
M. Niebelschütz, G. Ecke, V. Cimalla, K. Tonisch, O. Ambacher
Austrittsarbeitsanalyse von GaN basierten Lateral Polarity Strukturen durch Auger‐Elektronen‐Energie‐Messungen
2006 Materialwiss Werkst, Band: 37, Nummer: 11, Seiten: 937 - 940
Mohr A, Roth T, Glunz Stefan
BICON: high concentration PV using one-axis tracking and silicon concentrator cells: High concentration PV using one-axis tracking and silicon concentrator cells
2006 Progress in Photovoltaics: Research and Applications, Band: 14, Nummer: 7, Seiten: 663 - 674
J. Pezoldt, Yu. V. Trushin, V. S. Kharlamov, A. A. Schmidt, V. Cimalla, O. Ambacher
Carbon surface diffusion and SiC nanocluster self-ordering
2006 Nucl Instrum Meth B, Band: 253, Nummer: 1-2, Seiten: 241 - 245
Boljen M, Harwick W, Rohr I, Hiermaier S
Characterisation and numerical simulation of twill and satin weaves of fabrics made of p-Aramid under static and dynamic loading
2006 , Seiten: 345 - 352
KurzfassungThe aim of this work is to numerically model two representative twill and satin weaves on a mesoscopical level in order to reveal weave specific yarn interactions. These mesoscopical models that explicitly depict each participating yarn are subjected to uniaxial tension, quasi-static biaxial tension and pure shear loading. The material response of both weaves will be investigated and compared to experimental results performed earlier by Rohr and Harwick.
S. Shokhovets, G. Gobsch, O. Ambacher
Conduction band parameters of ZnO
2006 Superlattice Microst, Band: 39, Nummer: 1-4, Seiten: 299 - 305
V. Lebedev, F. M. Morales, V. Cimalla, J. G. Lozano, D. González, M. Himmerlich, S. Krischok, J. A. Schaefer, O. Ambacher
Correlation between structural and electrical properties of InN thin films prepared by molecular beam epitaxy
2006 Superlattice Microst, Band: 40, Nummer: 4-6, Seiten: 289 - 294
C. Buchheim, R. Goldhahn, A.T. Winzer, C. Cobet, M. Rakel, N. Esser, U. Rossow, D. Fuhrmann, A. Hangleiter, O. Ambacher
Critical points of the bandstructure of AlN/GaN superlattices investigated by spectroscopic ellipsometry and modulation spectroscopy
2006 physica status solidi c, Band: 3, Nummer: 6, Seiten: 2009 - 2013
G. Matthaeus, B. Pradarutti, C. Bruckner, St. Riehemann, G. Notni, St. Nolte, V. Cimalla, V. Lebedev, O. Ambacher, A. Tunnermann
Detailed Study of Differently Grown InN Wavers as Strong THz Surface Emitters Excited at 800 nm and 1060 nm
2006 Joint 31st International Conference on Infrared Millimeter Waves and 14th International Conference on Teraherz Electronics, Seiten: 369 - 369
R. Goldhahn, P. Schley, A. T. Winzer, G. Gobsch, V. Cimalla, O. Ambacher, M. Rakel, C. Cobet, N. Esser, H. Lu, W. J. Schaff
Detailed analysis of the dielectric function for wurtzite InN and In‐rich InAlN alloys
2006 Phys Status Solidi A, Band: 203, Nummer: 1, Seiten: 42 - 49
J. Pezoldt, Ch. Zgheib, V. Lebedev, P. Masri, O. Ambacher
Determination of strain and composition in SiC/Si and AlN/Si heterostructures by FTIR-ellipsometry
2006 Superlattice Microst, Band: 40, Nummer: 4-6, Seiten: 612 - 618
Bielawny A, Schweizer S, Miclea P, v. Rhein A, Wehrspohn R, van Riesen S, Glunz Stefan
Dispersive elements for spectrum splitting in solar cell applications
2006
KurzfassungPhotovoltaic tandem and triple solar cells are currently being developed and produced with reasonable efficiencies at high technological cost. The concept of spectrum splitting has been proposed with the advantage of compatibility to all types of cells. Although additional optical efforts are to be made, external photon management can be achieved to match different solar cell combinations no matter which band gaps involved or how the cells are connected. We present an experimental study comparing optical devices based on either interference or diffraction for tandem and triple cell configurations. Whereas diffractive media such as gratings suffer intrinsically from higher order diffraction losses, devices based on interference such as Bragg filter can yield a significant efficiency increase. For a triple cell configuration consisting of GaInP/GaInAs/GaSb, a net effciency gain of more than 30 % is shown in a solar cell simulator compared to the best cell in direct light.
V. Lebedev, F.M. Morales, H. Romanus, G. Ecke, V. Cimalla, M. Himmerlich, S. Krischok, J.A. Schaefer, O. Ambacher
Doping efficiency and segregation of Si in AlN grown by molecular beam epitaxy
2006 physica status solidi c, Band: 3, Nummer: 6
V. Lebedev, V. Cimalla, J. Pezoldt, M. Himmerlich, S. Krischok, J.A. Schäfer, O. Ambacher
Effect of dislocations on electrical and electron transport properties of InN thin films. I. Strain relief and formation of a dislocation network
2006 J Appl Phys, Band: 100, Nummer: 9
V. Lebedev, V. Cimalla, T. Baumann, O. Ambacher, F. M. Moralez, J. G. Lozano, G. Gonzales
Effect of dislocations on electrical and electron transport properties of InN thin films. II. Density and mobility of the carriers
2006 J Appl Phys, Band: 100, Nummer: 9
Ganzenmueller Georg, Koslowski Thorsten
Electronic conductivity in polyaromatic hydrocarbon glasses
2006 CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA JOURNAL OF CHEMICAL PHYSICS, AMER INST PHYSICS, Band: 125, Nummer: 1
KurzfassungBased upon Monte Carlo simulations of amorphous molecular glasses, we have computed the electronic structure of five prototypical polyaromatic hydrocarbons using an extended Su-Schrieffer-Heeger model [J. R. Schrieffer, W. P. Su, and A. J. Heeger, Phys. Rev. Lett. 42, 1698 (1979)]. In the presence of excess charges, the resulting potential energy surfaces have been analyzed using Marcus’ [Annu. Rev. Phys. Chem. 15, 155 (1964)] theory of charge transfer to yield reaction coefficients and-via the application of linear response theory-local conductivities. Applying Kirchhoff’s rules, the emerging random resistor network problem leads to global conductivities of the order of 10(-1)-1 S/cm, which correlate with the structural characteristics of the underlying geometry.
G. Cherkashinin, S. Krischok, M. Himmerlich, O. Ambacher, J. Schäfer
Electronic properties of C60/InP(001) heterostructures
2006 J Phys-condens Mat, Band: 18, Nummer: 43
S. Shokhovets, G. Gobsch, O. Ambacher
Excitonic contribution to the optical absorption in zinc-blende III-V semiconductors
2006 Phys Rev B, Band: 74, Nummer: 15
G. Ecke, M. Niebelschütz, R. Kosiba, U. Rossow, V. Cimalla, J. Liday, P. Worincic, J. Pezoldt, V. Lebedev, O. Ambacher
Fermi Level Analysis of Group III Nitride Semiconductor Device Structures by Auger Peak Position Measurements
2006 J Electr Eng-slovak, Band: 57, Nummer: 6
K. Tonisch, F. Niebelschuetz, V. Cimalla, H. Romanus, O. Ambacher
Fully Unstrained GaN on Thick AlN Layers for MEMS Application
2006 MRS Online Proceedings Library Archive, Band: 955
Cg. Zgheib, L. E. McNeil, P. Masri, Ch. Förster, F. M. Morales, Th. Stauden, O. Ambacher, J. Pezoldt
Ge-modified Si(100) substrates fort he growth of 3C-SiC(100)
2006 Appl Phys Lett, Band: 88, Nummer: 21
Ch. Förster, V. Cimalla, V. Lebedev, J. Pezoldt, K. Brueckner, R. Stephan, M. Hein, E. Aperathitis, O. Ambacher
Group III‐nitride and SiC based micro‐and nanoelectromechanical resonators for sensor applications
2006 Phys Status Solidi A, Band: 203, Nummer: 7, Seiten: 1829 - 1833
V. Cimalla, Ch. Förster, D. Cengher, K. Tonisch, O. Ambacher
Growth of AlN nanowires by metal organic chemical vapour deposition
2006 physica status solidi (b), Band: 243, Nummer: 7, Seiten: 1476 - 1480
Schultz O, Glunz Stefan, Riepe S, Willeke G
High-efficiency solar cells on phosphorus gettered multicrystalline silicon substrates
2006 Progress in Photovoltaics: Research and Applications, Band: 14, Nummer: 8, Seiten: 711 - 719
Hiermaier S
Hydrocodes - Simulation transienter VorgĂ¤nge mit expliziter Zeitintegration
2006
I. Cimalla, F. Will, K. Tonisch, M. Niebelschütz, V. Cimalla, V. Lebedev, G. Kittler, M. Himmerlich, S. Krischok, J. A. Schaefer, M. Gebinoga, A. Schober, T. Friedrich, O. Ambacher
Impact of device technology processes on the surface properties and biocompatibility of group III nitride based sensors
2006 Materialwiss Werkst, Band: 37, Nummer: 11, Seiten: 919 - 923
M. Hermann, F. Furtmayer, F. M. Morales, O. Ambacher, M. Stutzmann, M. Eickhoff
Impact of silicon incorporation on the formation of structural defects in AlN
2006 J Appl Phys, Band: 100, Nummer: 11
B. Pradarutti, G. Matthäus, C. Brückner, S. Riehemann, G. Notni, St. Nolte, V. Cimalla, V. Lebedev, O. Ambacher, A. Tünnermann
InN as THz emitter excited at 1060 nm and 800 nm
2006 Millimeter-Wave and Terahertz Photonics, Band: 6914
Kray D, Glunz Stefan
Investigation of laser-fired rear-side recombination properties using an analytical model
2006 Progress in Photovoltaics: Research and Applications, Band: 14, Nummer: 3, Seiten: 195 - 201
Thienelt, M., Eichhorn, A., Reiterer, A.
Kartenunabhängige Fußgängerortung – Prototyp eines wissensbasierten Kalman-Filters (WiKaF)
2006 Zeitschrift für Geodäsie, Geoinformation und Landmanagement (zfv), Seiten: 183 - 190

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Huberth F, Gerster T, Guth S, Hiermaier S
Kunststoffe in der Crashsimulation - Eine Betrachtung aus experimenteller Sicht unter BerĂźcksichtigung numerischer Problemstellungen
2006 , Seiten: 91 - 96
Reiterer, A.
Künstliche Intelligenz in der Ingenieurgeodäsie
2006 Zeitschrift für Geodäsie, Geoinformation und Landmanagement (zfv), Seiten: 141 - 147

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Meenken T, Hiermaier S
Large strain dynamic compression for soft materials using a direct impact experiment
2006 , Seiten: 653 - 659
L. H. Dmowski, K. Dybko, J. Plesiewics, T. Siski, H. Lu, W. Schaff, M. Kurouchi, Y. Nanishi, L. Konczewicz, V. Cimalla, O. Ambacher
Localized donor state above the conduction band minimum in
2006 Phys Status Solidi B, Band: 243, Nummer: 7, Seiten: 1537 - 1540
Ch. Förster, R. Kosiba, G. Ecke, V. Cimalla, O. Ambacher, J. Pezoldt
Low Energy Ion Modification of 3C-SiC Surfaces
2006 Materials science forum, Band: 527, Seiten: 685 - 688
E. Monroy, J. Zenneck, G. Cherkashinin, O. Ambacher, M. Hermann, M. Stutzmann, M. Eickhoff
Luminescence properties of highly Si-doped AlN
2006 Appl Phys Lett, Band: 88, Nummer: 7
Huberth F, Hiermaier S
Materialmodelle im Vergleich mit experimentell bestimmten Werkstoffverhalten
2006
Ch. Förster, V. Cimalla, M. Stubenrauch, C. Rockstuhl, K. Brueckner, M. A. Hein, J. Pezoldt, O. Ambacher
Micromachining of novel SiC on Si structures for device and sensor applications
2006 Materials Science Forum, Band: 527-529
G. Cherkashinien, O. Ambacher, T. Schiffer, G. Schmidt
Mobility edge in hydrogenated amorphous carbon
2006 Appl Phys Lett, Band: 88, Nummer: 17
V. Cimalla, V. Lebedev, F. M. Morlaes, R. Goldhahn, O. Ambacher
Model for the thickness dependence of electron concentration in InN films
2006 Appl Phys Lett, Band: 89, Nummer: 17
A. A. Schmidt, Yu. V. Trushin, K. L. Safonov, V. S. Kharlamov, D. V. Kulikov, O. Ambacher, J. Pezoldt
Multi-Scale Simulation of MBE-Grown SiC/Si Nanostructures
2006 Materials Science Forum, Band: 527, Nummer: 529
V. Lebedev, F. M. Morales, M. Fischer, M. Himmerlich, S. Krischok, J. A. Schäfer, O. Ambacher
Nanocrystalline AlN: Si field emission arrays for vacuum electronics
2006 Phys Status Solidi A, Band: 203, Nummer: 7
Glunz Stefan
New concepts for high-efficiency silicon solar cells
2006 Solar Energy Materials and Solar Cells, Band: 90, Nummer: 18-19, Seiten: 3276 - 3284
Hiermaier S, Gebbeken N
Numerische Berechnungsverfahren fĂźr dynamische Prozesse
2006
St. Voigt, U. Zhokhavets, H. Hoppe, G. Gobsch, M. Al-Ibrahim, O. Ambacher, St. Sensfuss
Optical investigation of P3HT/PCBM bulk heterojunction solar cells by photoinduced absorption spectroscopy
2006 Verhandlungen der Deutschen Physikalischen Gesellschaft, Band: 41, Nummer: 1
V. Cimalla, V. Lebedev, F. M. Morales, M. Niebelschütz, G. Ecke, R. Goldhahn, O. Ambacher
Origin of n‐type conductivity in nominally undoped InN
2006 Materialwiss Werkst, Band: 37, Nummer: 11, Seiten: 924 - 928
Ch. Wang, V. Cimalla, H. Romanus, T. Kups, G. Ecke, Th. Stauden, M. Ali, V. Lebedev, J. Pezoldt, O. Ambacher
Phase selective growth and properties of rhombohedral and cubic indium oxide
2006 Appl Phys Lett, Band: 89, Nummer: 1
Janz S, Riepe S, Hofmann M, Reber S, Glunz Stefan
Phosphorus-doped SiC as an excellent p-type Si surface passivation layer
2006 Applied Physics Letters, Band: 88, Nummer: 13
K. Tonisch, V. Cimalla, Ch. Foerster, H. Romanus, O. Ambacher, D. Dontsov
Piezoelectric properties of polycrystalline AlN thin films for MEMS application
2006 Sensor Actuat A-phys, Band: 132, Nummer: 2, Seiten: 658 - 663
K. Tonisch, V. Cimalla, Ch. Förster, D. Dontsov, O. Ambacher
Piezoelectric properties of thin AlN layers for MEMS application determined by piezoresponse force microscopy
2006 physica status solidi c, Band: 3, Nummer: 6, Seiten: 2274 - 2277
Schäfer M, Scholz J, Greiner M
Proactive robustness control of heterogeneously loaded networks.
2006 Phys Rev Lett, Band: 96, Nummer: 10, Seite: 108701
KurzfassungA proactive measure to increase the robustness of heterogeneously loaded networks against cascades of overload failures is proposed. It is based on load-dependent weights. Compared to simple hop weights, respective shortest flow paths turn a previously heterogeneous load distribution into a more homogeneous one for the nodes and links of the network. The use of these flow paths increases the networks robustness and at the same time reduces the investment costs into the networks capacity layout. These findings are of relevance for critical infrastructures like communication and transportation networks.
M. Ali, V. Cimalla, V. Lebedev, H. Romanus, V. Tilak, D. Merfeld, P. Sandvik, O. Ambacher
Pt/GaN Schottky diodes for hydrogen gas sensors
2006 Sensor Actuat B-chem, Band: 113, Nummer: 2, Seiten: 797 - 804
V. Cimalla, Ch. Foerster, F. Will, K, Tonisch, K. Brueckner, R. Stephan, M.E. Hein, E. Aperathidis, O. Ambacher
Pulsed mode operation of strained microelectromechanical resonators in air
2006 Appl Phys Lett, Band: 88, Nummer: 25
R. Kosiba, J. Liday, G. Ecke, O. Ambacher, J. Breza, P. Vogrincic
Quantitative Auger electron spectroscopy of SiC
2006 Vacuum, Band: 80, Nummer: 9, Seiten: 990 - 995
U. Zhokhavets, T. Erb, G. Gobsch, M. Al-Ibrahim, O. Ambacher
Relation between absorption and crystallinity of poly (3-hexylthiophene)/fullerene films for plastic solar cells
2006 Chem Phys Lett, Band: 418, Nummer: 4-5, Seiten: 347 - 350
M. Fischer, M. Stubenrauch, Th. Kups, H. Romanus, F. M. Morales, G. Ecke, M. Hoffmann, Ch. Knedlik, O. Ambacher, J. Pezoldt
Self organization and properties of Black Silicon
2006 Information technology and electrical engineering-devices and systems, materials and technologies for the future, Band: 51
Veit D, Weidlich A, Yao J, Oren S
Simulating the dynamics in two-settlement electricity markets via an agent-based approach
2006 International Journal of Management Science and Engineering Management, Band: 1, Seiten: 83 - 97
V. Cimalla, M. Niebelschütz, G. Ecke, V. Lebedev, O. Ambacher, M. Himmerlich, S. Krischik, J. A. Schäfer, H. Lu, W. J. Schaff
Surface band bending at nominally undoped and Mg‐doped InN by Auger Electron Spectroscopy
2006 Phys Status Solidi A, Band: 203, Nummer: 1, Seiten: 59 - 65
M. Himmerlich, St. Krischok, J. A. Schaefer, V. Lebedev, O. Ambacher
Surface characterization of InN grown by PIMBE
2006 Verhandlungen der Deutschen Physikalischen Gesellschaft, Band: 41, Nummer: 1
V. Cimalla, M. Niebelschütz, G. Ecke, O. Ambacher, R. Goldhahn, H. Lu, W. J. Schaff
The conductivity of Mg‐doped InN
2006 physica status solidi c, Band: 3, Nummer: 6, Seiten: 1721 - 1724
G. Cherkashinin, V. Lebedev, R. Wagner, I. Cimalla, O. Ambacher
The performance of AlGaN solar blind UV photodetectors: responsivity and decay time
2006 Phys Status Solidi B, Band: 243, Nummer: 7
P. Schley, R. Goldhahn, A. T. Winzer, G. Gobsch, V. Cimalla, O. Ambacher, M. Rakel, C. Cobet, N. Esser, H. Lu, W. J. Schaff
Transition energies and Stokes shift analysis for In‐rich InGaN alloys
2006 Phys Status Solidi B, Band: 243, Nummer: 7, Seiten: 1572 - 1576
Ch. Y. Wang, V. Cimalla, O. Ambacher
Tuning of electrical properties of In{sub x}O{sub y} thin films grown by MOCVD for different applications
2006 Materialwiss Werkst, Band: 37, Nummer: 11
C. Buchheim, G. Kittler, V. Cimalla, V. Lebedev, M. Fischer, S. Krischok, V. Yanev, M. Himmerlich, G. Ecke, J. A. Schaefer, O. Ambacher
Tuning of surface properties of AlGaN/GaN sensors for nanodroplets and picodroplets
2006 Ieee Sens J, Band: 6, Nummer: 4, Seiten: 881 - 886
Huberth F, Hiermaier S
Verrippte Bauteile - Kugelimpaktversuche und Simulationsergebnisse mit LS-DYNA
2006
I. Cimalla, Ch. Förster, V. Cimalla, V. Lebedev, D. Cengher, O. Ambacher
Wet chemical etching of AlN in KOH solution
2006 physica status solidi c, Band: 3, Nummer: 6, Seiten: 1767 - 1770
M. Niebelschütz, G. Ecke, V. Cimalla, K. Tonisch, O. Ambacher
Work function analysis of GaN-based lateral polarity structures by Auger electron energy measurements
2006 J Appl Phys, Band: 100, Nummer: 7

2005

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A. Schober, G. Kittler, C. Buchheim, A. Majdeddin, V. Cimalla, M. Fischer, V. Yanev, M. Himmerlich, S. Krischok, J. A. Schaefer, H. Romanus, T. Sändig, J. Burgold, F. Weise, H. Wurmus, K. H. Drüe, M. Hintz, H. Thust, M. Gebinoga, M. Kittler, A. Spitznas, E. Gottwald, K. F. Weibezahn, D. Wegener, A. Schwienhorst, O. Ambacher
A novel class of sensors for system integrative concepts in biotechnological applications
2005 Technical Proceedings of the 2005 NSTI Nanotechnology Conference and Trade Show
SchĂ¤fer F, Hiermaier S, Schneider E
Ballistic limit equation for the normal impact of unyawed ellipsoid-shaped projectiles on aluminium Whipple Shields
2005 Science and Technology Series, Band: 109, Seiten: 291 - 308
KurzfassungIn this study, an approach to cope with the impactor shape in ballistic limit assessment of Whipple shields is presented. A ballistic limit equation (BLE) for impacts of ellipsoid-shaped projectiles on Whipple Shields was derived from existing and thoroughly verified BLEs which were originally developed to yield the critical projectile diameter of spherical projectiles impacting on aluminium Whipple shields. The derived equation was validated by hypervelocity impact tests and numerical simulations. The Whipple Shields had a bumper thickness of 1.0 mm and backwall thicknesses of 3.0 mm and 4.0 mm, respectively, placed at a stand-off of 200 mm and 150 mm, respectively, from the bumper. The total number of impact tests on Whipple Shields performed was 39, covering shape factors of around 0.4, 1.0, and 1.53. Projectile masses amounted to between 0.18 g and 0.32 g. Impact velocities ranged between 0.85 km/s and 6.76 km/s. The numerical simulations of hypervelocity impacts on Whipple Shields with spherical and prolate shaped projectiles (f=1.53) covered the velocity range up to 13 km/s which is not accessible to experimental testing. 8 numerical simulation runs were performed. The BLE can be used to predict the critical projectile mass for a given projectile shape for normal and unyawed impact on aluminium Whipple Shields as a function of impact velocity.
Schaefer, F., Hiermaier, S., Schneider, E.
Ballistic limit equation for the normal impact of unyawed ellipsoid-shaped projectiles on aluminium Whipple Shields
2005 Science and Technology Series, Band: 109, Seiten: 291 - 308
KurzfassungIn this study, an approach to cope with the impactor shape in ballistic limit assessment of Whipple shields is presented. A ballistic limit equation (BLE) for impacts of ellipsoid-shaped projectiles on Whipple Shields was derived from existing and thoroughly verified BLEs which were originally developed to yield the critical projectile diameter of spherical projectiles impacting on aluminium Whipple shields. The derived equation was validated by hypervelocity impact tests and numerical simulations. The Whipple Shields had a bumper thickness of 1.0 mm and backwall thicknesses of 3.0 mm and 4.0 mm, respectively, placed at a stand-off of 200 mm and 150 mm, respectively, from the bumper. The total number of impact tests on Whipple Shields performed was 39, covering shape factors of around 0.4, 1.0, and 1.53. Projectile masses amounted to between 0.18 g and 0.32 g. Impact velocities ranged between 0.85 km/s and 6.76 km/s. The numerical simulations of hypervelocity impacts on Whipple Shields with spherical and prolate shaped projectiles (f=1.53) covered the velocity range up to 13 km/s which is not accessible to experimental testing. 8 numerical simulation runs were performed. The BLE can be used to predict the critical projectile mass for a given projectile shape for normal and unyawed impact on aluminium Whipple Shields as a function of impact velocity.
F.M. Morales, Ch. Förster, O. Ambacher, J. Pezoldt
Beta to alpha transition and defects on SiC on Si grown by CVD
2005 Microscopy of Semiconducting Materials, Seiten: 131 - 134
Ganzenmuller G, Berkaine N, Fouqueau A, Casida M, Reiher M
Comparison of density functionals for differences between the high-(T-5(2g)) and low-((1)A(1g)) spin states of iron(II) compounds. IV. Results for the ferrous complexes [Fe(L)(’NHS4’)]
2005 CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA JOURNAL OF CHEMICAL PHYSICS, AMER INST PHYSICS, Band: 122, Nummer: 23
KurzfassungPrevious work testing density functionals for use in calculating high-spin-low-spin energy differences, Delta E-HL, for iron(II) spin-crossover transitions has tended to conclude that only properly reparametrized hybrid functionals can predict Delta E-HL since it seems to depend critically on a correct description of the electron pairing energy governed by the exchange term. Exceptions to this rule are the previous three papers (I, II, and III in the present series of papers) where it was found that modern generalized gradient approximations (GGAs) and meta-GGAs could do as well as hybrid functionals, if not better, for this type of problem. In the present paper, we extend these previous studies to five more molecules which are too large to treat with high-quality ab initio calculations, namely, the series [Fe(L)(’NHS4’)], where NHS4=2.2(’)-bis(2-mercaptophenylthio)diethylamine dianion, and L=NH3, N2H4, PMe3, CO, and NO+. Since we know of no reliable experimental estimate of Delta E-HL, we content ourselves with a comparison against the experimentally determined ground-state spin symmetry including, in so far as possible, finite-temperature effects. Together with the results of Papers I, II, and III, this paper provides a test of a large number of functionals against the high-spin/low-spin properties of a diverse set of Fe(II) compounds, making it possible to draw some particulary interesting conclusions. Trends among different classes of functionals are discussed and it is pointed out that there is at least one functional, namely, the OLYP generalized gradient approximation, which is able to give a reasonably good description of the delicate spin energetics of Fe(II) coordination compounds without resorting to hybrid functionals which require the relatively more expensive calculation of a Hartree-Fock-type exchange term. (C) 2005 American Institute of Physics.
M. Al-Ibrahim, S. Sensfuss, J. Utziel, G. Ecke, O. Ambacher
Comparison of normal and inverse poly (3-hexylthiophene)/fullerene solar cell architectures
2005 Sol Energ Mat Sol C, Band: 85, Nummer: 2, Seiten: 277 - 283
K. L. Safonov, Y. V. Trushin, O. Ambacher, J. Pezoldt
Computer simulation of the early stages of nano scale SiC growth on Si
2005 Mater Sci Forum, Band: 483, Seiten: 169 - 172
V Lebedev, I Cimalla, V Cimalla, R Wagner, U Kaiser, O Ambacher
Defect related absorption and emission in AlGaN solar‐blind UV photodetectors
2005 physica status solidi (c), Band: 2, Nummer: 4, Seiten: 1360 - 1365
Ch. Zheib, M. Kazan, P. Weih, O. Ambacher, P. Masri, J. Pezoldt
Effect of Ge incorporation on stoichiometric composition of 3C‐SiC thin films grown on Si (111) substrates
2005 physica status solidi (c), Band: 2, Nummer: 4, Seiten: 1284 - 1287
V. Lebedev, V. Cimalla, U. Kaiser, Ch. Foerster, J. Pezoldt, J. Biskupek, O. Ambacher
Effect of nanoscale surface morphology on the phase stability of 3C-AlN films on Si (111)
2005 J Appl Phys, Band: 97, Nummer: 11
M. Al-Ibrahim, O. Ambacher, S. Sensfuss, G. Gobsch
Effects of solvent and annealing on the improved performance of solar cells based on poly (3-hexylthiophene): fullerene
2005 AIP, Band: 86, Nummer: 20, Seite: 201120
Reiterer, A.
Ein wissensbasiertes Entscheidungssystem für ein online Videotheodolit-basiertes Messsystem
2005 Zeitschrift für Geodäsie, Geoinformation und Landmanagement (zfv), Seiten: 218 - 225

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K. Brueckner, Ch. Forster, K. Tonisch, V. Cimalla, O. Ambacher, R. Stephan, K. Blau, M. A. Hein
Electromechanical resonances of SiC and AlN beams under ambient conditions
2005 European Microwave Conference, Band: 3
Rein S, Glunz Stefan
Electronic properties of interstitial iron and iron-boron pairs determined by means of advanced lifetime spectroscopy
2005 Journal of Applied Physics, Band: 98, Nummer: 11
Ch. Förster, V. Cimalla, E. Aperathitis, K. Brückner, R. Stephan, M. Hein, J. Pezoldt, O. Ambacher
Fabrication of 3C-SiC/Si MEMS and NEMS for sensor applications
2005 HeT-SiC-05
P. Weih, H. Romanus, Th. Stauden, L. Spieß, O. Ambacher, J. Pezoldt
Growth of 3C-(Si1-xC1-Y) Gex+ y layers on 4H-SiC by molecular beam epitaxy
2005 Mater Sci Forum, Band: 483, Seiten: 173 - 176
A. A. Schmidt, V. S. Kharlamov, K. L. Safonov, Y. V. Trushin, E. E. Zhurkin, V. Cimalla, O. Ambacher, J. Pezoldt
Growth of three-dimensional SiC clusters on Si modelled by KMC
2005 Comp Mater Sci, Band: 33, Nummer: 1-3
C. Rockstuhl, H.-P. Herzig, Ch. Förster, A. Leycuras, O. Ambacher, J. Pezoldt
Infrared gratings based on SiC/Si-heterostructures
2005 Mater Sci Forum, Band: 483-485, Seiten: 433 - 436
P. Weih, Th. Stauden, G. Ecke, S. Shokhovets, Ch. Zheib, M. Voelskow, W. Skorupa, O. Ambacher, J. Pezoldt
Ion beam synthesis of 3C–(Si1–xC1–y)Gex+y solid solutions
2005 Phys Status Solidi A, Band: 202, Nummer: 4, Seiten: 545 - 549
Thienelt, M., Eichhorn, A., Reiterer, A.
Konzept eines wissensbasierten KALMAN- Filters für die Fußgängerortung (WiKaF)
2005 Österreichische Zeitschrift für Vermessung und Geoinformation (VGI), Band: Nr. 93, Seiten: 96 - 104
Ch. Förster, V. Cimalla, O. Ambacher, J. Pezoldt
Low temperature chemical vapor deposition of 3C-SiC on Si substrates
2005 Mater Sci Forum, Band: 283, Seiten: 201 - 204
Huberth F, Hiermaier S, Neumann M
Material models for polymers under crash loads existing LS-DYNA models and perspectives
2005
Ch. Förster, V. Cimalla, K. Brückner, M. Hein, J. Pezoldt, O. Ambacher
Micro-electromechanical systems based on 3C-SiC/Si heterostructures
2005 Mat Sci Eng C-bio S, Band: 25, Nummer: 5-8, Seiten: 804 - 808
S. Shokhovets, G. Gobsch, O. Ambacher
Momentum matrix element and conduction band nonparabolicity in wurtzite GaN
2005 Appl Phys Lett, Band: 86, Nummer: 16
Teng X, Wierzbicki T, Hiermaier S, Rohr I
Numerical prediction of fracture in the Taylor test
2005 International Journal of Solids and Structures, Band: 42, Nummer: 9-10, Seiten: 2929 - 2948
Teng, X., Wierzbicki, T., Hiermaier, S., Rohr, I.
Numerical prediction of fracture in the Taylor test
2005 International Journal of Solids and Structures, Band: 42, Seiten: 2929 - 2948
V. Cimalla, V. Lebedev, U. Kaiser, R. Goldhahn, Ch. Förster, J. Pezoldt, O. Ambacher
Polytype control and properties of AlN on silicon
2005 physica status solidi (c), Band: 2, Nummer: 7, Seiten: 2199 - 2203
Ch. Förster, V. Cimalla, K. Brueckner, V. Lebedev, R. Stephan, M. Hein, O. Ambacher
Processing of novel SiC and group III‐nitride based micro‐and nanomechanical devices
2005 Phys Status Solidi A, Band: 202, Nummer: 4, Seiten: 671 - 676
Ch. Zgheib, L. E. McNeil, M. Kazan, P. Masri, F. M. Morales, O. Ambacher, J. Pezoldt
Raman studies of Ge-promoted stress modulation in 3C–SiC grown on Si (111)
2005 Appl Phys Lett, Band: 87, Nummer: 4
L. H. Dmowski, J. A. Piesiewicz, T. Suski, H. Lu, W. Schaff, L. Konczewicz, V. Cimalla, O. Ambacher
Resonant localized donor state above the conduction band minimum in InN
2005 Appl Phys Lett, Band: 86, Nummer: 26
P. Schley, R. Goldhahn, G. Gobsch, V. Cimalla, O. Ambacher, C. Cobet, N. Esser, J. Furthmueller, F. Bechstedt, H. Lu, W. J. Schaff
Selection rules for optical transitions of wurtzite InN
2005 Verhandlungen der Deutschen Physikalischen Gesellschaft, Band: 40, Nummer: 2
Nossek M, Sauer M, Riedel W, Hiermaier S
Simulation des EnergieaufnahmevermĂśgens von CFK-Strukturen bei Belastungen in der Laminatebene
2005 , Seiten: 53 - 66
Wicklein M, Hiermaier S, Thoma K
Simulation of cellular aluminium
2005 , Seiten: 111 - 114
Veit D, Weidlich A
Softwareagenten simulieren Handel mit Emissionszertifikaten
2005 Dow Jones TradeNews Emissions, Band: 10, Seiten: 10 - 11
F.M. Morales, P. Weih, Ch. Wang, Th. Stauden, O. Ambacher, J. Pezoldt
Strain relaxation and void reduction in SiC on Si by Ge predeposition
2005 Microscopy of Semiconducting Materials, Seiten: 135 - 138
J. Pezoldt, Ch. Zgheib, Ch. Förster, F.M. Morales, G. Cherkachinin, Ch. Wang, A. Leycuras, G. Ferro, Y. Monteil, I. Cimalla, O. Ambacher, P. Masri
Stress design in 3C-SiC/Si heteroepitaxial systems
2005 HeT-SiC-05
V. Cimalla, G. Ecke, M. Niebelschütz, O. Ambacher, R. Goldhahn, H. Lu, W. J. Schaff
Surface conductivity of epitaxial InN
2005 physica status solidi (c), Band: 2, Nummer: 7, Seiten: 2254 - 2257
V. Lebedev, F. M. Morales, H. Romanus, S. Krischok, G. Ecke, V. Cimalla, M. Himmerlich, T. Stauden, D. Cengher, O. Ambacher
The role of Si as surfactant and donor in molecular-beam epitaxy of AlN
2005 J Appl Phys, Band: 98, Nummer: 9
S. Shokhovets, G. Gobsch, O. Ambacher
kp parameters of Wurtzite GaN
2005 Verhandlungen der Deutschen Physikalischen Gesellschaft, Band: 40, Nummer: 2
F. M. Morales, Ch. Förtser, O. Ambacher, J. Pezoldt
α-SiC-β-SiC heteropolytype structures on Si (111)
2005 Appl Phys Lett, Band: 87, Nummer: 20

2004

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Thoma K, SchĂ¤fer F, Hiermaier S, Schneider E
An approach to achieve progress in spacecraft shielding
2004 Advances in Space Research, Band: 34, Nummer: 5, Seiten: 1063 - 1075
KurzfassungProgress in shield design against space debris can be achieved only when a combined approach based on several tools is used. This approach depends on the combined application of advanced numerical methods, specific material models and experimental determination of input parameters for these models. Examples of experimental methods for material characterization are given, covering the range from quasi static to very high strain rates for materials like Nextel and carbon fiber-reinforced materials. Mesh free numerical methods have extraordinary capabilities in the simulation of extreme material behaviour including complete failure with phase changes, combined with shock wave phenomena and the interaction with structural components. In this paper the benefits from combining numerical methods, material modelling and detailed experimental studies for shield design are demonstrated. The following examples are given: (1) Development of a material model for Nextel and Kevlar-Epoxy to enable numerical simulation of hypervelocity impacts on complex heavy protection shields for the International Space Station. (2) The influence of projectile shape on protection performance of Whipple Shields and how experimental problems in accelerating such shapes can be overcome by systematic numerical simulation. (3) The benefits of using metallic foams in "sandwich bumper shields" for spacecraft and how to approach systematic characterization of such materials.
Thoma, K., Schaefer, F., Hiermaier, S., Schneider, E.
An approach to achieve progress in spacecraft shielding
2004 Advances in Space Research, Band: 34, Seiten: 1063 - 1075
KurzfassungProgress in shield design against space debris can be achieved only when a combined approach based on several tools is used. This approach depends on the combined application of advanced numerical methods, specific material models and experimental determination of input parameters for these models. Examples of experimental methods for material characterization are given, covering the range from quasi static to very high strain rates for materials like Nextel and carbon fiber-reinforced materials. Mesh free numerical methods have extraordinary capabilities in the simulation of extreme material behaviour including complete failure with phase changes, combined with shock wave phenomena and the interaction with structural components. In this paper the benefits from combining numerical methods, material modelling and detailed experimental studies for shield design are demonstrated. The following examples are given: (1) Development of a material model for Nextel and Kevlar-Epoxy to enable numerical simulation of hypervelocity impacts on complex heavy protection shields for the International Space Station. (2) The influence of projectile shape on protection performance of Whipple Shields and how experimental problems in accelerating such shapes can be overcome by systematic numerical simulation. (3) The benefits of using metallic foams in "sandwich bumper shields" for spacecraft and how to approach systematic characterization of such materials.
SchĂ¤fer F, Hiermaier S, Schneider E
Ballistic limit equation for the normal impact of unyawed ellipsoid-shaped projectiles on aluminium whipple shields
2004 , Seiten: 291 - 308
F. Bechstedt, J. Furthmüller, O. Ambacher, R. Goldhahn
Comment on “Mie Resonances, Infrared Emission, and the Band Gap of InN”
2004 Phys Rev Lett, Band: 93, Nummer: 26
Sindelar R, Riedel W, Schaeuble R, Thielicke B, Hiermaier S
Failure mechanisms in layered composite materials for compressed hydrogen tanks
2004
KurzfassungStorage systems for compressed hydrogen used in automotive applications are internally sealed by a diffusion barrier made of polyethylene or aluminium reinforced by a layer of several millimetres thick carbon fiber composite. A layer of impact resistant glass fiber covers the pressure vessel against external impact damage on the carbon shell. For safety reasons tank systems are qualified by several standardized tests. The main reason for these tests is to ensure that nocatas trophic failure of the tank could occur. Investigation on catastrophic failure of high performance composite materials was undertaken by testing and numerical simulation. Here the influence of preload during penetration of the laminate was investigated. A report of the current research is given.
Schultz O, Glunz Stefan, Willeke G
SHORT COMMUNICATION: ACCELERATED PUBLICATION: Multicrystalline silicon solar cells exceeding 20% efficiency
2004 Progress in Photovoltaics: Research and Applications, Band: 12, Nummer: 7, Seiten: 553 - 558
Reiterer, A., Kahmen, H., Egly, U., Eiter, T.
Wissensbasierte Bildaufbereitung für ein videotheodolit-basiertes Multisensorsystem
2004 Allgemeine Vermessungs-Nachtrichten, Band: Nr. 6, Seiten: 202 - 208

2003

nach oben zur Jahresübersicht

Reiterer, A., Egly, U., Eiter, T., Kahmen, H.
3D-Messverfahren mit Videotheodoliten und automatisierte Zielpunkterfassung mit Hilfe von Interest Operatoren
2003 Allgemeine Vermessungs-Nachrichten, Band: Nr. 4, Seiten: 150 - 156
Hiermaier S, Sauer M
Adaptive FE-Meshfree-Modelling for Impacts of Liquid Filled Vessels on Thin Walled Structures
2003 , Seiten: 43 - 48
KurzfassungA principal approach to simulate the airplane impact and the collapse of World Trade Center North Tower has been shown by Quan and Birnbaum [4]. Using the general purpose hydrocode AUTODYN the impact damage, fire induced strength reduction and progressive collapse were investigated. Both for the fuel propagation after tank break up and the thermodynamic burn processes assumptions have been taken. It is the aim of this paper to focus on the numerical aspects of simulating the fluid propagation after vessel break up. The release of a fluid out of a broken vessel after impact is not easily represented in a numerical simulation as the fluid flow and its interaction with structures can not be modelled using Lagrangian type element formulations. These elements, typically applied for structural analyses, fail under massive deformation and usually need then to be taken out of the simulation. Typical fluid dynamic discretization methods, so called Eulerian grids, would have to cover the whole space potentially being reached by the fluid flow and are therefore inefficient in a large three dimensional simulation. As an alternative method a coupled discretization using Lagrange elements and Lagrange type meshfree methods is proposed here. Meshfree methods have been introduced to structural dynamics more then ten years ago specifically to simulate processes including large deformation [1]. Originally developed as pure meshfree code, the EMI SOPHIA [3] provides now a new form of adaptivity that allows for more efficiency and accuracy. This is achieved by the use of finite elements as long as deformation is capable for the elements. At definable strain or failure thresholds any element can be transformed into one or more meshfree particles. This way, mass and volume of the original elements are conserved. As the particles interact with each other as well as with the remaining elements, all physical processes can be modelled continuously. The purpose of this study was to contribute to numerical simulation of the airplane impacts into the World Trade Center. It includes impact simulations of cylindrical vessels filled with water against thin walled rectangular shaped bars. It shows that coupled discretizations and specifically an adaptive FE-meshfree discretization offer the flexibility needed to gain both accuracy and efficiency in the simulation.
Clegg R, White D, Hayhurst C, Riedel W, Harwick W, Hiermaier S
Advanced numerical models and material characterisation techniques for composite materials subject to impact and shock wave loading
2003 Journal de physique. 4, Colloque, Band: 110, Seiten: 311 - 316
KurzfassungThe development and validation of an advanced material model for orthotropic materials, such as fibre reinforced composites, is described. The model is specifically designed to facilitate the numerical simulation of impact and shock wave propagation through orthotropic materials and the prediction of subsequent material damage. Initial development of the model concentrated on correctly representing shock wave propagation in composite materials under high and hypervelocity impact conditions. This work has now been extended to further concentrate on the development of improved numerical models and material characterisation techniques for the prediction of damage, including residual strength, in fibre reinforced composite materials. The work is focussed on Kevlar-epoxy however materials such as CFRP are also being considered. The paper describes our most recent activities in relation to the implementation of advanced material modelling options in this area. These enable refined non-liner directional characteristics of composite materials to be modelled, in addition to the correct thermodynamic response under shock wave loading. The numerical work is backed by an extensive experimental programme covering a wide range of static and dynamic tests to facilitate derivation of model input data and to validate the predicted material response. Finally, the capability of the developing composite material model is discussed in relation to a hypervelocity impact problem.
Clegg, R.A., White, D.M., Hayhurst, C., Riedel, W., Harwick, W., Hiermaier, S.
Advanced numerical models and material characterisation techniques for composite materials subject to impact and shock wave loading
2003 Journal de physique. 4, Colloque, Band: 110, Seiten: 311 - 316
KurzfassungThe development and validation of an advanced material model for orthotropic materials, such as fibre reinforced composites, is described. The model is specifically designed to facilitate the numerical simulation of impact and shock wave propagation through orthotropic materials and the prediction of subsequent material damage. Initial development of the model concentrated on correctly representing shock wave propagation in composite materials under high and hypervelocity impact conditions. This work has now been extended to further concentrate on the development of improved numerical models and material characterisation techniques for the prediction of damage, including residual strength, in fibre reinforced composite materials. The work is focussed on Kevlar-epoxy however materials such as CFRP are also being considered. The paper describes our most recent activities in relation to the implementation of advanced material modelling options in this area. These enable refined non-liner directional characteristics of composite materials to be modelled, in addition to the correct thermodynamic response under shock wave loading. The numerical work is backed by an extensive experimental programme covering a wide range of static and dynamic tests to facilitate derivation of model input data and to validate the predicted material response. Finally, the capability of the developing composite material model is discussed in relation to a hypervelocity impact problem.
Rein S, Glunz Stefan
Electronic properties of the metastable defect in boron-doped Czochralski silicon: Unambiguous determination by advanced lifetime spectroscopy
2003 Applied Physics Letters, Band: 82, Nummer: 7
Isenberg J, Riepe S, Glunz Stefan, Warta W
Imaging method for laterally resolved measurement of minority carrier densities and lifetimes: Measurement principle and first applications
2003 Journal of Applied Physics, Band: 93, Nummer: 7, Seiten: 4268 - 4275
Wicklein M, Sauer M, Klomfass A, Hiermaier S, Thoma K
Mesomechanical simulation of cellular aluminium
2003 , Seiten: 369 - 374
Hiermaier S
Numerik und Werkstoffdynamik der Crash- und ImpaktvorgĂ¤nge
2003 Fraunhofer IRB Verlag, Stuttgart, Fraunhofer IRB Verlag, Stuttgart
KurzfassungTheorie und Experiment der Werkstoffcharakterisierung fĂźr dynamisches Materialverhalten sind zwei Welten, die sich vielfach getrennt voneinander entfalten. Zusammen mit der numerischen Methodenentwicklung sind dies die drei obligatorischen Bausteine einer physikalisch sinnvollen Simulation von Crash- und ImpaktvorgĂ¤ngen. Im Automobilcrash, beim Impakt von FlugkĂśrpern auf harte oder gepanzerte Strukturen wie auch beim Einschlag von Mikrometeoriten in Raumfahrzeugen treten kurzzeitige Belastungen der jeweiligen Werkstoffe auf, die mit groĂen zeitlichen Ănderungen der Druck-, Dichte- und VerformungszustĂ¤nde einhergehen. Ziel der vorliegenden Arbeit ist es, fĂźr diese drei Anwendungsbereiche die theoretischen Grundlagen sowohl fĂźr die Formulierung mathematischer Modelle als auch fĂźr die Definition und DurchfĂźhrung von Experimenten zur Ermittlung von Materialparametern zusammenzustellen. Die Arbeit spiegelt eine wesentliche Bestrebung des Autors in seiner TĂ¤tigkeit am Ernst-Mach-Institut wider, die bestehenden Forschungsteams zur dynamischen MaterialprĂźfung und zur numerischen Methodenentwicklung zusammenzufĂźhren. Grundlagen und ausgewĂ¤hlte Ergebnisse der gleichzeitigen experimentellen und numerischen Untersuchung der Strukturdynamik bei Crash und Impakt werden dargestellt.
Hiermaier S, SchĂ¤fer F
Simulation of ellipsoidal projectile impact on whipple shields
2003 International Journal of Impact Engineering, Band: 29, Nummer: 1-10, Seiten: 333 - 343
Hiermaier, S.J., Schaefer, F.K.
Simulation of ellipsoidal projectile impact on whipple shields
2003 International Journal of Impact Engineering, Band: 29, Seiten: 333 - 343

2002

nach oben zur Jahresübersicht

Corley J, Riedel W, Hiermaier S, Weidemaier P, Thoma K
A combined experimental/computational approach for assessing the high strain rate response of high explosive simulants and other viscoelastic particulate composite materials
2002 , Seiten: 705 - 708
Dicker J, Schumacher J, Warta W, Glunz Stefan
Analysis of one-sun monocrystalline rear-contacted silicon solar cells with efficiencies of 22.1%
2002 Journal of Applied Physics, Band: 91, Nummer: 7
Fiorentini Vincenzo, Bernardini Fabio, Ambacher Oliver
Evidence for nonlinear macroscopic polarization in III–V nitride alloy heterostructures
2002 AIP, Band: 80, Nummer: 7, Seiten: 1204 - 1206
Schneiderlöchner E, Preu R, Lüdemann R, Glunz Stefan
Laser-fired rear contacts for crystalline silicon solar cells
2002 Progress in Photovoltaics: Research and Applications, Band: 10, Seiten: 29 - 34
Rein S, Rehrl T, Warta W, Glunz Stefan
Lifetime spectroscopy for defect characterization: Systematic analysis of the possibilities and restrictions
2002 Journal of Applied Physics, Band: 91, Nummer: 4, Seiten: 2059 - 2070
Hiermaier S, Sauer M, Peter J, Thoma K
Modeling the continuum/discrete transition using adaptive meshfree methods
2002
Altermatt P, Schumacher J, Cuevas A, Kerr M, Glunz Stefan, King R, Heiser G, Schenk A
Numerical modeling of highly doped Si:P emitters based on Fermi–Dirac statistics and self-consistent material parameters: P emitters based on Fermi-Dirac statistics and self-consistent material parameters
2002 Journal of Applied Physics, Band: 92, Nummer: 6
Hiermaier S, Sauer M, Thoma K
Predictive crash simulation using adaptive finite methods
2002 , Seiten: 27 - 38
Ambacher O, Majewski J, Miskys C, Link Al, Hermann M, Eickhoff M, Stutzmann M, Bernardini Fabio, Fiorentini Vincenzo, Tilak V
Pyroelectric properties of Al (In) GaN/GaN hetero-and quantum well structures
2002 IOP Publishing, Band: 14, Nummer: 13, Seite: 3399
Rohr I, Hiermaier S, Thoma K
The erosion process during KE-Penetration
2002 , Seiten: 1175 - 1181

2001

nach oben zur Jahresübersicht

Glunz Stefan, Rein S, Warta W, Knobloch J, Wettling W
Degradation of carrier lifetime in Cz silicon solar cells
2001 Solar Energy Materials and Solar Cells, Band: 65, Nummer: 1-4, Seiten: 219 - 229
Thoma K, Riedel W, SchĂ¤fer F, Hiermaier S
Hypervelocity impacts and protection
2001 , Seiten: 555 - 568
Schmidt J, Cuevas A, Rein S, Glunz Stefan
Impact of light-induced recombination centres on the current-voltage characteristic of Czochralski silicon solar cells
2001 Progress in Photovoltaics: Research and Applications, Band: 9, Nummer: 4, Seiten: 249 - 255
Youn Lee J, Peters S, Rein S, Glunz Stefan
Improvement of charge minority-carrier lifetime in p(Boron)-type Czochralski silicon by rapid thermal annealing
2001 Progress in Photovoltaics: Research and Applications, Band: 9, Nummer: 6, Seiten: 417 - 424
Kress A, Breitenstein O, Glunz Stefan, Fath P, Willeke G, Bucher E
Investigations on low-cost back-contact silicon solar cells
2001 Solar Energy Materials and Solar Cells, Band: 65, Nummer: 1-4, Seiten: 555 - 560
Glunz Stefan, Rein S, Lee J, Warta W
Minority carrier lifetime degradation in boron-doped Czochralski silicon
2001 Journal of Applied Physics, Band: 90, Nummer: 5
Palmieri D, SchĂ¤fer F, Hiermaier S, Lambert M
Numerical simulation of non-perforating impacts on shielded gas-filled pressure vessels
2001 , Seiten: 591 - 602
Heider N, Hiermaier S
Numerical simulation of the performance of tandem warheads
2001 , Seiten: 1493 - 1499
SchĂ¤fer F, Herrwerth M, Hiermaier S, Schneider E
Shape effects in hypervelocity impact on semi-infinite metallic targets
2001 , Seiten: 699 - 712
Eastman Lester F, Tilak Vinayak, Smart J, Green Bruce M, Chumbes Eduardo M, Dimitrov Roman, Kim Hyungtak, Ambacher Oliver S, Weimann N, Prunty T
Undoped AlGaN/GaN HEMTs for microwave power amplification
2001 IEEE, Band: 48, Nummer: 3, Seiten: 479 - 485

2000

nach oben zur Jahresübersicht

Glunz Stefan, Köster B, Leimenstoll T, Rein S, Schäffer E, Knobloch J, Abe T
100 cm2 solar cells on Czochralski silicon with an efficiency of 20.2%
2000 Progress in Photovoltaics: Research and Applications, Band: 8, Nummer: 2, Seiten: 237 - 240
Warta W, Glunz Stefan, Dicker J, Knobloch J
Highly efficient 115-µm-thick solar cells on industrial Czochralski silicon
2000 Progress in Photovoltaics: Research and Applications, Band: 8, Nummer: 5, Seiten: 465 - 471
Pfleging W, Ludwig A, Seemann K, Preu R, Mäckel H, Glunz Stefan
Laser micromachining for applications in thin film technology
2000 Applied Surface Science, Band: 154-155, Seiten: 633 - 639
Saitoh T, Hashigami H, Rein S, Glunz Stefan
Overview of light degradation research on crystalline silicon solar cells
2000 Progress in Photovoltaics: Research and Applications, Band: 8, Nummer: 5, Seiten: 537 - 547
Thoma K, Riedel W, SchĂ¤fer F, Hiermaier S
Status and perspectives in protective design
2000 Space debris, Band: 2, Nummer: 4, Seiten: 201 - 224
KurzfassungStarting with an introduction into the field of hypervelocity impacts, an overview over current research in the area of protection against space debris is given. Trends and strategies to further develop know-how in protection technology are then discussed. One purpose is to demonstrate that improvements in shield efficiency can be expected. To achieve this aim, a strategy is outlined which tries to avoid the adjustment of numerical and material parameters by fits to penetration experiments. Instead, it is suggested to determine material parameters from carefully selected laboratory tests, covering a broad range of strains, strain rates and stress states. Knowledge of the dynamic material behaviour can then be used for the development of new shield concepts by means of numerical simulation.
Thoma, K., Riedel, W., Schaefer, F., Hiermaier, S.
Status and perspectives in protective design
2000 Space debris, Band: 2, Seiten: 201 - 224
KurzfassungStarting with an introduction into the field of hypervelocity impacts, an overview over current research in the area of protection against space debris is given. Trends and strategies to further develop know-how in protection technology are then discussed. One purpose is to demonstrate that improvements in shield efficiency can be expected. To achieve this aim, a strategy is outlined which tries to avoid the adjustment of numerical and material parameters by fits to penetration experiments. Instead, it is suggested to determine material parameters from carefully selected laboratory tests, covering a broad range of strains, strain rates and stress states. Knowledge of the dynamic material behaviour can then be used for the development of new shield concepts by means of numerical simulation.
Ambacher O, Foutz B, Smart J, Shealy JR, Weimann NG, Chu K, Murphy M, Sierakowski AJ, Schaff WJ, Eastman LF
Two dimensional electron gases induced by spontaneous and piezoelectric polarization in undoped and doped AlGaN/GaN heterostructures
2000 AIP, Band: 87, Nummer: 1, Seiten: 334 - 344

1999

nach oben zur Jahresübersicht

Glunz Stefan, Rein S, Knobloch J, Wettling W, Abe T
Comparison of boron- and gallium-doped p-type Czochralski silicon for photovoltaic application
1999 Progress in Photovoltaics: Research and Applications, Band: 7, Nummer: 6, Seiten: 463 - 469
Hayhurst C, Hiermaier S, Clegg R, Riedel W, Lambert M
Development of material models for Nextel and Kevlar-epoxy for high pressures and strain rates
1999 International Journal of Impact Engineering, Band: 23, Nummer: 1, Part 1, Seiten: 365 - 376
Hayhurst, C.J., Hiermaier, S.J., Clegg, R.A., Riedel, W., Lambert, M.
Development of material models for Nextel and Kevlar-epoxy for high pressures and strain rates
1999 International Journal of Impact Engineering, Band: 23, Seiten: 365 - 376
Glunz Stefan, Biro D, Rein S, Warta W
Field-effect passivation of the SiO2Si interface
1999 Journal of Applied Physics, Band: 86, Nummer: 1, Seiten: 683 - 691
Hiermaier, S., Schaefer, F.
Hypervelocity impact fragment clogh-pressure gas numerical and experimental investigations
1999 International Journal of Impact Engineering, Band: 23, Seiten: 391 - 400
Hiermaier S, Schäfer F
Hypervelocity impact fragment clouds in high-pressure gas numerical and experimental investigations
1999 International Journal of Impact Engineering, Band: 23, Seiten: 391 - 400
Kelly Michael K, Vaudo Robert P, Phanse Vivek M, Görgens Lutz, Ambacher Oliver, Stutzmann Martin
Large free-standing GaN substrates by hydride vapor phase epitaxy and laser-induced liftoff
1999 IOP Publishing, Band: 38, Nummer: 3A, Seite: L217
Schaefer S, Lüdemann R, Glunz Stefan
Self-aligned metallization and reactive ion etched buried base contact solar cells
1999 Progress in Photovoltaics: Research and Applications, Band: 7, Nummer: 5, Seiten: 387 - 392
Ambacher O., Smart J., Shealy J. R., Weimann N.G., Chu K., Murphy M.
Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N-and Ga-face AlGaN/GaN heterostructures
1999 J Appl Phys, Band: 85, Nummer: 6, Seiten: 3222 - 3233

1998

nach oben zur Jahresübersicht

Thoma K, Hiermaier S, Riedel W
Beton unter dynamischer Beanspruchung
1998
KurzfassungZur Berechnung von kurzzeitdynamischen VorgĂ¤ngen wie Impakt und explosiver Belastung werden Finite-Element-Programm vom Typ ’Hydrocodes’ verwendet. Durch inkrementelle Stoffgesetze bei expliziter Zeitintegration sind sie zur Modellierung von komplexen Materialverhalten geeignet. Die mechanischen Eigenschaften von Beton sind von InhomogenitĂ¤t und PorositĂ¤t geprĂ¤gt. In dem Beitrag werden nichtlineare Materialmodelle der Kontinuumsmechanik unter BerĂźcksichtigung von SchĂ¤digung mit mikromechanischen AnsĂ¤tzen verglichen. Die nĂśtigen Materialparameter werden am Ernst-Mach-Institut in verschiedenen statischen und dynamischen Tests bestimmt. Im Labor kĂśnnen Geschwindigkeiten bis zu 10 km/s erreicht werden. Die Koppelung von Ergebnissen aus Planar-Impakt-Experimenten mit Materialmodellen und Rechnungen wird an Beton und seinen Komponenten aufgezeigt.
Metzger T, Höpler R, Born E, Ambacher O, Stutzmann M, Stömmer R, Schuster M, Göbel H, Christiansen S, Albrecht M
Defect structure of epitaxial GaN films determined by transmission electron microscopy and triple-axis X-ray diffractometry
1998 Taylor & Francis, Band: 77, Nummer: 4, Seiten: 1013 - 1025
Ambacher Oliver
Growth and applications of group III-nitrides
1998 IOP Publishing, Band: 31, Nummer: 20, Seite: 2653

1997

nach oben zur Jahresübersicht

Schmidt J, Schuurmans F, Sinke W, Glunz Stefan, Aberle A
Observation of multiple defect states at silicon–silicon nitride interfaces fabricated by low-frequency plasma-enhanced chemical vapor deposition
1997 Applied Physics Letters, Band: 71, Nummer: 2, Seiten: 252 - 254
Brunner D, Angerer H, Bustarret E, Freudenberg F, Höpler R, Dimitrov R, Ambacher O, Stutzmann M
Optical constants of epitaxial AlGaN films and their temperature dependence
1997 AIP, Band: 82, Nummer: 10, Seiten: 5090 - 5096
Hebling C, Glunz Stefan, Schetter C, Knobloch J, Räuber A
Silicon thin-film solar cells on insulating intermediate layers
1997 Solar Energy Materials and Solar Cells, Band: 48, Nummer: 1-4, Seiten: 335 - 342

1996

nach oben zur Jahresübersicht

Füssel W, Glunz Stefan, Warta W
Innovative Charakterisierungsverfahren zur Unterstützung der Solarzellentechnologie
1996 Forschungsverbund Sonnenenergie Themen 95/96, Seiten: 37 - 43
Glunz Stefan, Hebling C, Warta W
Lifetime and material characteristics of multicrystalline silicon measured with high spatial resolution
1996 Solid State Phenomena, Band: 51-52, Seiten: 69 - 74
Glunz Stefan, Schumacher J, Warta W, Knobloch J, Wettling W
Solar cells with mesh-structured emitter
1996 Progress in Photovoltaics: Research and Applications, Band: 4, Nummer: 6, Seiten: 415 - 424

1995

nach oben zur Jahresübersicht

Glunz Stefan, Warta W
High-resolution lifetime mapping using modulated free-carrier absorption
1995 Journal of Applied Physics, Band: 77, Nummer: 7, Seiten: 3243 - 3247

1994

nach oben zur Jahresübersicht

Aberle A, Glunz Stefan, Stephens A, Green M
High-eficiency silicon solar cells: Si/SiO2, interface parameters and their impact on device performance: Si/SiO2 interface parameters and their impact on device performance
1994 Progress in Photovoltaics: Research and Applications, Band: 2, Nummer: 4, Seiten: 265 - 273
Glunz Stefan, Sproul A, Warta W, Wettling W
Injection-level-dependent recombination velocities at the Si-SiO2 interface for various dopant concentrations
1994 Journal of Applied Physics, Band: 75, Nummer: 3, Seiten: 1611 - 1615

1993

nach oben zur Jahresübersicht

Aberle A, Glunz Stefan, Warta W
Field effect passivation of high efficiency silicon solar cells
1993 Solar Energy Materials and Solar Cells, Band: 29, Nummer: 2, Seiten: 175 - 182

1992

nach oben zur Jahresübersicht

Aberle A, Glunz Stefan, Warta W
Impact of illumination level and oxide parameters on Shockley–Read–Hall recombination at the Si-SiO2 interface
1992 Journal of Applied Physics, Band: 71, Nummer: 9

Reviews/Übersichtsartikel in wissenschaftlichen Fachzeitschriften

Jahre: 2008

zurück zur Übersicht aller Publikationen

2008

nach oben zur Jahresübersicht

Weidlich A, Veit D
A critical survey of agent-based wholesale electricity market models
2008 Energy Economics, Band: 30, Seiten: 1728 - 1759

Datei herunterladen

Monographien

Jahre: 2015 | 2014 | 2012 | 2011 | 2010 | 2009 | 2008

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2015

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Reiner-Lemoine-Stiftung
Low-Concentrating, Stationary Solar Thermal Collectors for Process Heat Generation
Hess, S
G Stryi-Hipp, Woodhead, Cambridge
Solar Thermal Technologies for Process Heating
ISBN: 978-1-78242-213-6
Hess S

2014

nach oben zur Jahresübersicht

Numerical sensitivity studies of a UHMWPE composite for ballistic protection
Numerical sensitivity studies of a UHMWPE composite for ballistic protection
LĂ¤ssig T, Riedel W, Heisserer U, Werff H, May M, Hiermaier S
KurzfassungUltra-high molecular weight polyethylene (UHMWPE) has a high potential for ballistic armor applications due to the excellent weight specific strength inherent to this type of material. In this paper, a non-linear orthotropic material model for the UHMWPE, based on the product DYNEEMAÂŽ HB26, is used for assessing the influence of the material properties on the ballistic performance. The model, implemented in the commercial hydrocode ANSYS AUTODYN uses initially linear-orthotropic elasticity, subsequent non-linear strain hardening, multiple stress-based composite failure criteria and post-failure softening. The strength model is coupled with a polynomial equation of state. An experimentally supported material data set for UHMWPE, presented before, is used as a baseline for the numerical studies on high velocity impact. Parameter sensitivities are studied for these impact situations. The numerical predictions are compared to available experimental data over a wide range of impact velocities (1 km/s up to 6 km/s). The objective of this paper is to assess the influence of different material parameters on the predictive capability of high velocity impact simulations and subsequently provide guidelines for the required experimental characterization of UHMWPE under shock loading.

2012

nach oben zur Jahresübersicht

Springer-Verlag
Future Energy Grid: Migrationspfade ins Internet der Energie
Dänekas C, König A, Mayer C, Rohjans S, Bischoff S, Breuer A, Drzisga T, Hecht J, Holtermann M, Luhmann T, Maerten M, Stadler M, Terzidis O, Plöger W, Theisen T, Wortmann F, Weidlich A, Weinmann J, Winter R, Wissing C

2011

nach oben zur Jahresübersicht

Crashverhalten von Polymerwerkstoffen
Crashverhalten von Polymerwerkstoffen
Hiermaier Stefan

2010

nach oben zur Jahresübersicht

Selbstheilende Polymere
Selbstheilende Polymere
Haase T, Thoma K, Hiermaier S

2009

nach oben zur Jahresübersicht

Hypervelocity impact induced shockwaves and related equations of state
Hypervelocity impact induced shockwaves and related equations of state
Hiermaier S
KurzfassungPrecondition for stable shock wave propagation is a convex Equation of State (EoS) in terms of pressure and volume. The first mathematical proof for the existence and dependence of shock waves on that non-linearity was derived by Bethe [1]. In this introductory chapter, a more phenomenological approach to derive conditions for shock wave formation will be given along with some examples for Equations of State used in hydrocodes.
Introduction
Introduction
Hiermaier S
Springer, Berlin
Predictive modeling of dynamic processes : A tribute to Professor Klaus Thoma
ISBN: 978-1-4419-0726-4
Hiermaier, S

2008

nach oben zur Jahresübersicht

Physica-Verlag Springer, Seite: 174
Engineering interrelated electricity markets: an agent-based computational approach
Weidlich A
Springer US, Berlin
Structures under crash and impact : Continuum mechanics, discretization and experimental characterization
ISBN: 978-0-387-73862-8
Hiermaier, S.J.

Buchbeiträge

Jahre: 2020 | 2019 | 2018 | 2017 | 2016 | 2015 | 2014 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2004 | 1998

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2020

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Becker, Denise;, Stemmler, Simon;, Reiterer, Alexander
Entwicklung und Evaluierung eines kompakten Multisensorsystems für den Einsatz auf Drohnen
In: Ingenieurvermessung 20 Beiträge zum 19. Internationalen Ingenieurvermessungskurs München, 2020
2020, Wichmann, Thomas A. Wunderlich, Seiten: 99 - 108, Thomas A. Wunderlich, ISBN: 978-3-87907-672-7
Schäfer M, Tranberg B, Greiner M
Power flows in complex renewable energy networks
In: Discoveries at the Frontiers of Science
2020, Springer, Seiten: 239 - 251,
Reiterer, Alexander;, Störk, Dominik;, Wäschle, Katharina;, Leydecker, Achim
Vollautomatisierte Auswertung von Mobile-Mapping-Daten mithilfe von Machine Learning
In: Ingenieurvermessung 20 Beiträge zum 19. Internationalen Ingenieurvermessungskurs München, 2020
2020, Wichmann, Thomas A. Wunderlich, Seiten: 141 - 147, Thomas A. Wunderlich, ISBN: 978-3-87907-672-7

2019

nach oben zur Jahresübersicht

Hiermaier, Stefan, Scharte, Benjamin, Fischer, Kai
Resilience Engineering: Chances and challenges for a comprehensive concept
In: Handbook on resilience of socio-technical systems
2019, Cheltenham: Elgar, 2019, Ruth, Matthias, Seiten: 155 - 166, Ruth, Matthias, ISBN: 978-1-78643-936-9
KurzfassungEver more complex socio-technical systems enable modern societies to profit from most technological developments in everyday life. New means of communication and transport, cheap energy and supply goods as well as stable global business opportunities are the basis for the comfortable environment many modern civilizations have to offer. The related technological innovations involve manifold interdependencies and complexities in the system behavior never known before. As a consequence, safe operation of critical infrastructure and secure environment for societies have to face a new quality of challenges demanding for new approaches in safety and security research.

2018

nach oben zur Jahresübersicht

F. Balle, D. Backe
Very High Cycle Fatigue of Carbon Fiber Reinforced Polyphenylene Sulfide at Ultrasonic Frequencies
In: Fatigue of Materials at Very High Numbers of Loading Cycles
2018, Springer Spektrum, H.-J. Christ, Seiten: 441 - 461, H.-J. Christ,

2017

nach oben zur Jahresübersicht

Reiterer, A., Predehl, K., Leidinger, M.
Die Entwicklung von Laserscannern - Herausforderungen bei neuartigen Anwendungen
In: Terrestrisches Laserscanning 2017 (TLS 2017) Beiträge zum 165. DVW-Seminar am 11. und 12. Dezember 2017 in Fulda
2017, Wißner-Verlag, DVW - Gesellschaft für Geodäsie, Geoinformation und Landmanagement e.V., Seiten: 9 - 21, DVW - Gesellschaft für Geodäsie, Geoinformation und Landmanagement e.V., ISBN: 9783957861450
Schäfer M, Hempel S, Tranberg B, Hörsch J, Schramm S, Greiner M
Power Flow Tracing in Complex Networks
In: New Horizons in Fundamental Physics
2017, Springer International Publishing, Seiten: 357 - 373,
KurzfassungThe increasing share of decentralized renewable power generation represents a challenge to the current and future energy system. Providing a geographical smoothing effect, long-range power transmission plays a key role for the system integration of these fluctuating resources. However, the build-up and operation of the necessary network infrastructure incur costs which have to be allocated to the users of the system. Flow tracing techniques, which attribute the power flow on a transmission line to the geographical location of its generation and consumption, represent a valuable tool set to design fair usage and thus cost allocation schemes for transmission investments. In this article, we introduce a general formulation of the flow tracing method and apply it to a simplified model of a highly renewable European electricity system. We review a statistical usage measure which allows to integrate network usage information for longer time series, and illustrate this measure using an analytical test case.

2016

nach oben zur Jahresübersicht

Haering, Ivo, Scharte, Benjamin, Stolz, Alexander, Leismann, Tobias, Hiermaier, Stefan
Resilience engineering and quantification for sustainable systems development and assessment: Socio-technical systems and critical infrastructure
In: IRGC Resource Guide on Resilience. Online resource
2016, IRGC Resource Guide on Resilience. Online resource, Online im WWW, Seite: 9, Online im WWW,

2015

nach oben zur Jahresübersicht

Helmke, A, Hess, S
Classification of Solar Process Heat System Concepts
In: Integration Guideline - Guideline for Solar Planners, Energy Consultants and Process Engineers
2015, B Mus-ter, Seiten: 61 - 76,

2014

nach oben zur Jahresübersicht

Glunz S
Crystalline silicon solar cells with high efficiency
In: Advanced concepts in photovoltaics
2014, Cambridge and United Kingdom The Royal Society of Chemistry, Band: 11, Seiten: 1 - 29,
Reiterer, A.
Erfassung großer Bereiche mit 3D-Laserscanning
In: Leitfaden zur optischen 3D-Messtechnik (Fraunhofer Vision Leitfaden-Reihe Band 14)
2014, Fraunhofer,
Laessig, T., Riedel, W., Heisserer, U., Werff, H. van der, May, M., Hiermaier, S.
Numerical sensitivity studies of a UHMWPE composite for ballistic protection
In: Structures under shock and impact
2014, Structures under shock and impact, WIT Press, Southampton, Seiten: 371 - 381, WIT Press, Southampton, ISBN: 978-1-84564-796-4
KurzfassungUltra-high molecular weight polyethylene (UHMWPE) has a high potential for ballistic armor applications due to the excellent weight specific strength inherent to this type of material. In this paper, a non-linear orthotropic material model for the UHMWPE, based on the product DYNEEMA� HB26, is used for assessing the influence of the material properties on the ballistic performance. The model, implemented in the commercial hydrocode ANSYS AUTODYN uses initially linear-orthotropic elasticity, subsequent non-linear strain hardening, multiple stress-based composite failure criteria and post-failure softening. The strength model is coupled with a polynomial equation of state. An experimentally supported material data set for UHMWPE, presented before, is used as a baseline for the numerical studies on high velocity impact. Parameter sensitivities are studied for these impact situations. The numerical predictions are compared to available experimental data over a wide range of impact velocities (1 km/s up to 6 km/s). The objective of this paper is to assess the influence of different material parameters on the predictive capability of high velocity impact simulations and subsequently provide guidelines for the required experimental characterization of UHMWPE under shock loading.

2012

nach oben zur Jahresübersicht

Glunz, SW, Preu, R., Biro, D.
Crystalline silicon solar cells: state-of-the-art and future developments
In: Comprehensive renewable energy, Vol. 1
2012, Elsevier, Sayigh, A., Seiten: 353 - 387, Sayigh, A.,
Weidlich A, Vogt H, Krauss W, Spiess P, Jawurek M, Johns M, Karnouskos S
Decentralized intelligence in energy efficient power systems
In: Handbook of Networks in Power Systems I
2012, Handbook of Networks in Power Systems I, Seiten: 467 - 486,
Hess, S, Lauterbach, C, Schmitt, B
Solare Prozesswärme
In: Solarthermische Anlagen: Leit-faden für das SHK-, Elektro- und Dachdeckerhandwerk, Fachplaner, Architekten, Bauherren und Weiterbildungsinstitutionen
2012, Kasper, B-R & Weyers-Borchert B,, Deutsche Gesellschaft für Sonnenenergie, Deutsche Gesellschaft für Sonnenenergie,

2011

nach oben zur Jahresübersicht

Hiermaier, Stefan
Crashverhalten von Polymerwerkstoffen
In: Handbuch Leichtbau
2011, Handbuch Leichtbau, Hanser, Muenchen, Hanser, Muenchen, ISBN: 978-3-446-42267-4
Karnouskos S, Weidlich A, Ringelstein J, Dimeas A, Kok K, Warmer C, Selzam, Patrick, Drenkard, Stefan, Hatziargyriou, Nikos, Lioliou, Vally
Monitoring and control for energy efficiency in the smart house
In: Energy Efficient Computing and Networking, Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering 54(3)
2011, Springer, Seiten: 197 - 207,

2010

nach oben zur Jahresübersicht

Haase, T., Thoma, K., Hiermaier, S.
Selbstheilende Polymere
In: Festschrift zum 60. Geburtstag von Univ.-Prof. Dr.-Ing. Ingbert Mangerig
2010, Festschrift zum 60. Geburtstag von Univ.-Prof. Dr.-Ing. Ingbert Mangerig, Universit�t der Bundeswehr Muenchen, Institut fuer Mechanik und Statik, Neubiberg, Universit�t der Bundeswehr Muenchen, Institut fuer Mechanik und Statik, Neubiberg,

2009

nach oben zur Jahresübersicht

Hiermaier, S.
Hypervelocity impact induced shockwaves and related equations of state
In: Predictive modeling of dynamic processes
2009, Predictive modeling of dynamic processes, Springer, Berlin, Seiten: 333 - 348, Springer, Berlin, ISBN: 978-1-4419-0726-4
KurzfassungPrecondition for stable shock wave propagation is a convex Equation of State (EoS) in terms of pressure and volume. The first mathematical proof for the existence and dependence of shock waves on that non-linearity was derived by Bethe [1]. In this introductory chapter,
Hiermaier S
Predictive modeling of dynamic processes
2009, Springer, Berlin, ISBN: 978-1-4419-0726-4 and 978-1-4419-0727-1

2008

nach oben zur Jahresübersicht

Hiermaier S
Structures under crash and impact
2008, Springer US, Berlin, ISBN: 978-0-387-73862-8 and 0-387-73862-2
Weidlich A, Sensfuß F, Genoese M, Veit D
Studying the effects of CO2 emissions trading on the electricity market: A multi-agent-based approach
In: Emissions Trading - Institutional Design, Decision Making and Corporate Strategies
2008, Physica-Verlag Springer, Seiten: 91 - 101,

2007

nach oben zur Jahresübersicht

Veit D, Weidlich A
Preissegmentierung im deutschen Strommarkt -- Ein interaktives Pricing-Konzept im Retail-Markt
In: Interactive Marketing im Web 2.0+
2007, Vahlen, Seiten: 165 - 180,

2004

nach oben zur Jahresübersicht

Paar, G., Huber, N. B., Bauer, A., Avian, M., Reiterer, A
Vision-Based Terrestrial Surface Monitoring
In: Terrigenous Mass Movements
2004, Springer Verlag, Springer Berlin Heidelberg, Seiten: 283 - 348, Springer Berlin Heidelberg, ISBN: 978-3-642-25494-9

1998

nach oben zur Jahresübersicht

Rein S, Diez S, Falster R, Glunz Stefan
Quantitative correlation of the metastable defect in Cz-silicon with different impurities
In: Scanning electron microscopy - physics of image formation and microanalysis
1998, Berlin Heidelberg New York Tokyo Springer-Verlag GmbH, Seiten: 1048 - 1052,

Vorträge

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2019

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M. Becker, F. Balle
Multi-spot ultrasonic welding of Al/Steel-joints for automotive applications
2019 International Congress on Ultrasonics, Brügge
F. Staab, F. Balle
Ultrasonic welding of ageing resistant hybrid transition structures for future aircraft applications
2019 International Congress on Ultrasonics, Brügge
S. Backe, T. Beck, F. Balle
SHORT-TIME APPROACH FOR FATIGUE LIFE ESTIMATION OF MULTIFUNCTIONAL COMPOSITES
2019 ICCM22, Melbourne Australia

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F. Staab, F. Balle
Mikrostruktur- und Eigenschaftsanalyse ultraschalltorsionsgeschweißter Al/CFK-Verbunde
2019 Symposium Verbundwerkstoffe und Werkstoffverbunde, Kaiserslautern
M. Becker
Serielles Ultraschallpunktschweißen von Aluminium/Stahl-Verbunden
2019 Symposium Verbundwerkstoffe und Werkstoffverbunde, Kaiserslautern
M. Becker, F. Balle
Serielles Ultraschallpunktschweißen von Aluminium/Stahl-Verbunden
2019 22. Symposiums für Verbundwerkstoffe und Werkstoffverbunde

2018

nach oben zur Jahresübersicht

M. Becker
Untersuchungen zum seriellen Ultraschallpunktschweißen von Aluminium/Stahl-Verbunden
2018 DGM Fachausschuss Hybride Werkstoffe und Strukturen zusammen mit dem Arbeitskreis Mischverbindungen mit Aluminium des Fachausschusses Aluminium, Kaiserslautern
Unnewehr J, Waldl H-P, Pahlke P, Herráez I
Reducing operational costs of offshore HVDC energy export systems through optimized maintenance
2018 17th Wind Integration Workshop
F. Staab, F. Balle
Ultraschalltorsionsschweißen von alterungsbeständigen Al/CFK-Verbunden – Konzepte, Prozess und Eigenschaften
2018 3. Hybrid Materials and Structures, Bremen
F. Staab, F. Balle
Prozessuntersuchungen zum Ultraschallschweißen von alterungsbeständigen Al/CFK-Übergangsstrukturen
2018 DGM-Fachausschuss „Hybride Werkstoffe und Strukturen", Dortmund
Laessig, Torsten, Bagusat, Frank, Pfändler, Siegfried, May, Michael, Riedel, Werner, Heisserer, Ulrich, Werff, Harm van der, Sauer, Martin, Hiermaier, Stefan
Influence of the consolidation pressure on the shock wave propagation in UHMWPE composites
2018 1st World Conference on Advanced Materials for Defense (AuxDefense 2018), Lisbon, Portugal, September 3 and 4, 2018

2017

nach oben zur Jahresübersicht

F. Staab, F. Balle, J. Born
Ultraschalltorsionsschweißen von alterungsbeständigen Al/CFK-Verbunden – Prozess-, Mikrostruktur- und Eigenschaftsanalyse
2017 21. Symposium Verbundwerkstoffe und Werkstoffverbunde, Bremen
F. Staab, F. Balle
Ultraschalltorsionsschweißen von alterungsbeständigen Al/CFK-Verbunden: Konzepte, Herstellung und Eigenschaften
2017 DGM-Fachausschuss „Hybride Werkstoffe und Strukturen", Clausthal-Zellerfeld

2016

nach oben zur Jahresübersicht

F. Staab, F. Balle, J. Born
Joining of Light Metals to Fiber Reinforced Thermoplastic Composites by Power Ultrasonics for the Application in Hybrid Aircraft Structures
2016 3rd International Conference and Exhibition on Thermoplastic Composites (ITHEC), Bremen
Künzel T, Klumpp F, Weidlich A, Stuible A
Flexibility Options for Integrating Renewable Energy and Grid Stability
2016 10th International Renewable Energy Storage Conference IRES, Düsseldorf

2015

nach oben zur Jahresübersicht

Reiterer, A.
Mobiles Laserscanning – Aktuelle Trends
2015 TLS 2015, Fulda
Künzel T, Weidlich A
ÖkoFlex - Flexibility as an economic commodity in the intelligent energy system for the efficient integration of renewable energies
2015 Science Technology Conference, Karlsruhe

2014

nach oben zur Jahresübersicht

Reiterer, A.
Development and Evaluation of a Lightweight Laser Scanning System for Small UAVs
2014 SPAR, Amsterdam
Reiterer, A.
Laserscanning – Ein Überblick
2014 AKG User Conference, Köln

2013

nach oben zur Jahresübersicht

Reiterer, A.
Ein neuartiges Konzept auf der Basis von Laser Scanning Technologie zur Querebenheitsmessung von Straßenoberflächen
2013 BAUSCAN, Magdeburg
Reiterer, A.
Fast and Reliable Pavement Profile Scanning
2013 SPAR, Amsterdam

2012

nach oben zur Jahresübersicht

Weidlich A
Challenges for the Market Integration of Renewables with Smart Grids
2012 IEEE PES Innovative Smart Grid Technologies (ISGT) Europe Conference, Berlin

2011

nach oben zur Jahresübersicht

Reiterer, A.
Aufgaben, Trend und Perspektiven in der Ingenieurgeodäsie und geodätischen Messtechnik
2011 Interne Seminarreihe, Technische Universität Graz
Reiterer, A.
Issues, Trends and Perspectives in Engineering Geodesy
2011 Geosensorics and Engineering Geodesy, ETH-Zürich
Reiterer, A.
Monitoring von natürlichen Objekten – Strategien und Techniken zur Automatisierung. Hangbewegungen – Moderne Fernerkundungs- und Datenanalysemethoden
2011 Workshop am Lehrstuhl für Ingenieurgeologie der Technischen Universität München

2010

nach oben zur Jahresübersicht

Reiterer, A.
Anwendungen bildgebender Tachymeter
2010 Gesellschaft zur Kalibrierung geodätischer Messmittel, Leica Geosystems, Heerbrugg
Reiterer, A.
Image-Based Total Stations – A Novel Sensor for Geosciences
2010 ESF Topo- Europe Summer School on Detecting Landscape Change, Loen, Norwegen
Reiterer, A.
Intelligentes Geo-Monitoring in der Ingenieurgeodäsie
2010 DVW-Vortrag, TU-München

2009

nach oben zur Jahresübersicht

Reiterer, A.
Bildgestützte / intelligente Erfassung von Deformationen in der Ingenieurgeodäsie
2009 Interner Seminarvortrag, Hannover
Reiterer, A.
Intelligente bildgebende Sensorik im Anwendungsbereich der Ingenieurgeodäsie
2009 DVW-Vortrag, Darmstadt
Reiterer, A.
i-MeaS – Konzept und Realisierung eines intelligenten bildgestützten Monitoring Systems
2009 DVW-Vortrag, Braunschweig

2008

nach oben zur Jahresübersicht

Reiterer, A.
Deformation Measurement by Image-Assisted Total Station – State of the Art and Future Developments
2008 Technologieforum Leica Geosystems, Heerbrugg

2007

nach oben zur Jahresübersicht

Reiterer, A.
Intelligente Steuerung bildgebender Sensoren in der Ingenieurgeodäsie
2007 Verleihung des Karl-Rinner-Preises, Graz

2006

nach oben zur Jahresübersicht

Reiterer, A.
Anwendungen der Künstlichen Intelligenz für die Ingenieurgeodäsie
2006 9. Österreichischer Geodätentag, Krems an der Donau
Reiterer, A.
Smart Image-Based Sensors – Overview and Outlook
2006 Technologieforum Leica Geosystems, Heerbrugg

2005

nach oben zur Jahresübersicht

Reiterer, A.
New Methods for Image-Based Point Detection
2005 Institute of Geodesy and Photogrammetry, ETH-Zürich

2004

nach oben zur Jahresübersicht

Reiterer, A.
Ein wissensbasiertes Entscheidungssystem für ein online Multisensor System
2004 BRIMOS-Workshop, Universität für Bodenkultur, Wien

Konferenzbeiträge

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2020

nach oben zur Jahresübersicht

D. Merkle;, A. Schmitt;, A. Reiterer
SENSOR EVALUATION FOR CRACK DETECTION IN CONCRETE BRIDGES
2020 Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., Seiten: 1107 - 1114
KurzfassungBridges are one of the most critical traffic infrastructure objects, therefore it is necessary to monitor them at regular intervals. Nowadays, this monitoring is made manually by visual inspection. In recent projects, the authors are developing automated crack detection systems to support the inspector. In this pre-study, different sensors, like different camera systems for photogrammetry, a laser scanner, and a laser triangulation system are evaluated for crack detection based on a defined required minimum crack width of 0.2 mm. The used test object is a blasted concrete plate, sized 70 cm × 70 cm × 5 cm and placed in an outdoor environment. The results of the data acquisition with the different sensors are point clouds, which make the results comparable. The point cloud from the chosen laser scanner is not sufficient for the required crack width even at a low speed of 1 m/s. The RGB or intensity information of the photogrammetric point clouds, even based on a low-cost smartphone camera, contain the targeted cracks. The authors advise against using only the 3D information of the photogrammetric point clouds for crack detection due to noise. The laser triangulation system delivers the best results in both intensity and 3D information. The low weight of camera systems makes photogrammetry to the preferred method for an unmanned aerial vehicle (UAV). In the future, the authors aim for crack detection based on the 2D images, automated by using machine learning, and crack localisation by using structure from motion (SfM) or a positioning system.

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Negassi M.,, Parupalli U.,, Suarez-Ibarrola R.,, Schmitt A.,, Hein S.,, Miernik A.,, Reiterer A.
3D-Reconstruction and Semantic Segmentation of Cystoscopic Images
2020 MICAD2020; Oxford, UK

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Heimsath A, Sutardhio C, Schöttl P, Nitz P
Soiling of Solar Mirrors - Impact of Incidence Angles on CSP Plant Performance
2020 25th Solar Power And Chemical Energy Systems International Symposium SolarPACES 2019 25th Solar Power And Chemical Energy Systems International Symposium SolarPACES, Band: 1

2019

nach oben zur Jahresübersicht

D. Weibel, T. Beck, F. Balle
Fatigue properties and damage of CF-PPS from high to very high cycles
2019 ICCM22, Melbourne Australia

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A. Reiterer,, D. Störk,, K. Wäschle,, A. Leydecker,, M. Leidinger
Automatisierte Interpretation von 3D-Daten - Stand der Technik und zukünftige Entwicklungen
2019 1. Kolloquium Straßenbau in der Praxis; Ostfildern TAE Technische Akademie Esslingen, Technische Akademie Esslingen; F. Schäfer, Seiten: 453 - 456
M. Leidinger,, A. Reiterer,, D. Steiger
Pavement Profile Scanner PPS-Plus - Unerreichte Präzision bei hohen Geschwindigkeiten
2019 1. Kolloquium Straßenbau in der Praxis; Ostfildern TAE Tagungshandbuch 2019, TAE Technische Akademie Esslingen; F. Schäfer, Seiten: 327 - 331
Ujwala P.,, Pentek Q.,, Hein S.,, Miernik A.,, Reiterer A.
Image based 3D reconstruction of the bladder using structure-from-motion – Proof of principle in a phantom model
2019 European Association of Urology
Kurzfassung#AM19-1411
Vierhub-Lorenz Valentin Predehl Katharina, Wolf Sebastian Christoph S. Werner Christoph S., Kühnemann, Frank, Reiterer, Alexander
A multispectral tunnel inspection system for simultaneous moisture and shape detection
2019 SPIE Remote Sensing, 2019, Strasbourg, France , Band: Vol. 11157, 111570T
KurzfassungIn this paper, we present the implementation of a differential-absorption measurement-technique for surface moisture detection into a laser scanner aiding modern tunnel inspections. The use of laser scanners for tunnel inspections can reduce costly tunnel closures and provide digital data, compliant with modern building information modeling (BIM). Unfortunately, available systems are typically limited to pure 3D mapping. The Fraunhofer Institute for Physical Measurement Techniques IPM is developing a novel multi-parameter laser scanning system. For the first time, this system allows the simultaneous measurement of 3D-geometry, remission and surface moisture. The scanner measures simultaneously with two collinear laser beams with distinct wavelengths. One is centered at the absorption band of water at 1450 nm wavelength, while the other, with 1320 nm wavelength, is used as an intensity reference. The intensity ratio gives a good estimate of the surface water content. Additionally, the power of both lasers is modulated with a high frequency. This enables simultaneous measurement of the distance by comparing the phase difference of the backscattered light with a local reference. With this approach, we are able to record up to two million points per second containing distance, intensity and moisture information. Besides the technical implementation, we present point clouds from multiple test objects and surfaces. The presented data nicely demonstrates the ability to differentiate between absolute intensity variations, e.g. caused by dirt, and actual water contamination.
Luderer C., Messmer C., Bivour M., Hermle M.
Contact Resistivity of the TCO/a-Si:H/c-Si Heterojunction
2019 , Seite: 538–540
Kurzfassungsiehe pdf!
Klaas Björn, Baulig Claudia, Predehl,Katharina, Schwarzer, Stefan
Development of a multispectral scanning lidar system for measuring wind velocity, air temperature and moisture
2019 SPIE Remote Sensing, 2019, Strasbourg, France
KurzfassungMeasurements of atmospheric parameters, such as wind velocity, air temperature and moisture, provide important information for a diverse set of ﬁelds, ranging from estimating energy output of wind farms to predicting extreme weather events to understanding urban climatology. Performing these measurements quickly, reliably and with high accuracy presents a yet unsolved challenge. Especially when working in or close to complex terrain, such as forests, hillsides or urban landscapes, no available system can properly perform such measurements. The Fraunhofer Institute for Physical Measurement Techniques IPM is developing a novel multispectral scanning LiDAR system. The goal is to simultaneously and accurately measure wind speed, air temperature and moisture over complex terrain for the ﬁrst time. We present the current state of a scanner system for synchronized steering of multiple laser beams from diﬀerent LiDAR units towards positions in the commonly visible intersection volume, subtending up to 7/8th of the full solid angle. We also present the state of an in-house developed Doppler Wind LiDAR and our current proposal for a combined wind, air temperature and water vapor LiDAR.
Stemmler, Simon, Werner, Christoph S., Reiterer, Alexander
Development of a time-of-ﬂight laser scanning system for underwater applications
2019 SPIE Remote Sensing, 2019, Strasbourg, France , Band: 111500M, 11150 (1-6)
KurzfassungAn increasing number of underwater construction projects demand a solution for precise and highly resolved infrastructure monitoring which cannot be addressed by conventional sonar systems. We present an optical ranging system based on the pulsed time-of-ﬂight method incorporating a signal-processing toolchain especially equipped for mapping technical infrastructure. This allows us to handle multiple returns from objects which are only separated by a 15 cm gap. A high lateral resolution of 4 mm in combination with a high measurement rate of 50 000 measurements per second allows the reconstruction of ﬁne details. The measurement range can reach several 10 m, depending on the water quality. Further, we present the system design of our scanner and discuss ﬁrst results obtained in an underwater measurement range.
Qussous R, Künzel T, Weidlich A
Effects of a Coal Phase-Out on Market Dynamics: Results from a Simulation Model for Germany
2019 16th International Conference on the European Energy Market

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Dlugosch, Michael, Fritsch, Jens, Hiermaier, Stefan, Lukaszewicz, Dirk
Efficiency-driven model simplifications in crash simulations of FRP-metal hybrid material systems in automotive body structures
2019 International Conference on Simulation Process and Data Management (SPDM) 2019, Quebec A world of engineering simulation. NWC 2019, NAFEMS World Congress : 17-20 June, Quebec City, Canada : incorporating SPDM, International Conference Simulation Process & Data Management : summary of pr, International Association for the Engineering Analysis Community -NAFEMS-:, Seite: 21
KurzfassungGrowingly stringent CO2-emission regulations lead to increased efforts to explore novel multi-material systems for effective lightweight design solutions. These often exhibit a complex internal architecture including interfaces between the discrete material phases. Particularly in highly nonlinear crash simulations of complex structures, model fidelity is a key aspect in the trade-off considerations between accurate predictive capabilities of a modeling technique and the resources needed for model development as well as computationally producing and processing solutions. The present study investigates various model simplification strategies for Finite Element (FE)-simulations of automotive crash structural concepts composed of fiber-reinforced plastics (FRP)-metal hybrid material systems in view of the conflicts invoked by strict model efficiency requirements. This particularly implies the modeling resolution of the FRP phase and different modeling techniques for the adhesive interface between the material phases and the respective implications on the predictive qualities of the simulation results. All results are compared to hardware experiments of hybrid generic structural components under crash loading conducted by the authors. The results show, that the model fidelity in the FRP phase does generally have a strong correlation with the predictive capabilities of the overall simulation. Comparing the simulation and the experimental data of generic components shows that explicitly modeling the cohesive behavior at the adhesive interface is not only more complex, it is also not necessarily bound to produce more accurate results than a simple modeling approach using rigid tie connections. In terms of computational efficiency however, the tie modeling approach does not decrease the computational time solving the model, which limits potential efficiency benefits to the reduced modeling complexity and the omission of the adhesive’s characterization process.

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Maus S., Lohmüller S., Mu D., Schön J., Niewelt T., Wolf A., Preu R.
Impact of POCl3 Diffusion Process Parameters on Oxygen Precipitation in Czochralski-Grown Silicon
2019 , Seite: 151–156
Kurzfassungsiehe pdf!
Bett Alexander, Schulze Patricia, Winkler Kristina, Kabakli Özde, Bivour Martin, Cojocaru Ludmila, Ketterer Ines, Mundt Laura, Tutsch Leonard, Hermle Martin, Glunz Stefan, Goldschmidt Jan, Kamat Prashant, Angelis Filippo, Di Carlo Aldo
Monolithic perovskite silicon tandem solar cells with high-bandgap perovskite absorber exceeding 1.8 V open-circuit voltage
2019 Fundació Scito
Schäfer M, Hofmann F, Abdel-Khalek H, Weidlich A
Principal Cross-Border Flow Patterns in the European Electricity Markets
2019 16th International Conference on the European Energy Market

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Wanapinit N, Weidlich A, Thomsen J
Promoting flexibility from prosumers through a generic characteristic flexibility model
2019 11. Internationale Energiewirtschaftstagung an der TU Wien
KurzfassungEnergy systems require flexibility - an ability to respond to changes - to integrate higher shares of variable renewable energy. On the whole, flexibility potential from prosumers is significant and stems from various processes. As each flexibility option is unique, before utilization, its potential first must be assessed. This paper presents a universal flexibility model, so called generic characteristic flexibility model (GCM), as tool to characterize and assess most, if not all, flexibility options from prosumers. GCM establishes a generic flexible process with components representing physical parts, e.g. machine and storage, and various administrative decisions, e.g. changes in output delivery or operating hours. Each component is described with essential characteristics and constraints. As demonstrations, three flexible systems representing various sectors – a district heating system, a household appliance, and a production process - are characterized and modelled using GCM. Flexibility in these systems is utilized to minimize costs under time-varying electricity prices and subject to operational constraints. This in turn proves the concept of a universal flexibility model. GCM eases burdens of actors - flexibility providers and users - to develop assessment tools for each flexibility options. Its pre-defined structure and characteristics also support identification of flexible processes and communication between actors. Thus, it helps promoting the utilization of flexibility from prosumers.

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Fischer, Kai, Hiermaier, Stefan, Riedel, Werner, Häring, Ivo
Statistical driven vulnerability assessment for the resilience quantification of urban areas
2019 13th International Conference on Applications of Statistics and Probability in Civil Engineering (ICASP), ICASP 2019, Seoul Online resource : Seoul, South Korea, May 26-30, 2019 Seoul, 2019 http://s-space.snu.ac.kr/handle/10371/142934 Paper 26, 8 S., Band: 26, Seite: 8
KurzfassungThe formation of new threats and the increasing complexity of infrastructure elements underline the need for more robust and sustainable systems, which are able to cope with adverse events. Achieving sustainability requires the increase of resilience. Currently, a comprehensive approach for the quantification of resilience is missing. Within this paper, a new generalized mathematical framework is presented to assess the resilience of complex systems, like urban areas. A clear definition of terms and their interaction builds the basis of this assessment scheme. Risk-based approaches are extended with the dimension of time, to quantify the susceptibility, the vulnerability and the recovery behavior of complex systems for multiple threat scenarios. Engineering approaches are applied to assess expected damage effects and are combined with statistical methods to weight the probability of occurrence and the exposition of the investigated system to the source of disruptive events. Resilience is covered by indicators for preparation, prevention, protection, response and recovery. The presented approach is able to determine these indicators and provides decision support, which enhancement measures are more effective. Hence, the framework quantifies, if it is better to avoid a hazardous event or to tolerate an event with an increased robustness, for example. An application example assesses urban areas with consideration of multiple adverse events, like terrorist attacks or earthquakes, and multiple buildings. Each urban object includes a certain number of attributes, like the object use, the construction type, the time-dependent number of persons and the value to derive different performance targets. The assessment results in the identification of weak-spots through the evaluation of single resilience indicators.
Messmer C., Fell A., Feldmann F., Schön J., Hermle M.
Upgrade PERC with TOPCon: Efficiency Potential by Taking into Account the Electrical Gains and Optical Losses
2019
Kurzfassungsiehe pdf!

2018

nach oben zur Jahresübersicht

Ledford, Noah, Paul, Hanna, Isakov, Matti, Hiermaier, Stefan
High rate loading of hybrid joints in a Split Hopkinson Tension Bar
2018 International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading (DYMAT)/Arcachon EPJ Web of Conferences, Band: 183
KurzfassungBonded joints are nowadays seen as one of the preferred joining methods in aerospace applications. However, the difficulty in certifying bond strength and the relatively low energy absorption capability of the joint are barriers to widespread adoption. The use of a hybrid joint, that is, the combination of a mechanical and a bonded joint, allows for a fail-safe design and offers improved performance of the joint. The quasi-static properties of hybrid joints have been investigated by a number of researchers. In contrast, the high rate loading regime has been only sparsely investigated. In this work, hybrid joints are tested in quasi-static and high rate loading in order to analyze their loading rate dependence. The hybrid joint studied is a composite-aluminum double lap shear joint with Sikaforce 7752 adhesive and Hi-Lite-315 countersunk titanium bolts. In order to quantitatively analyze the high rate behavior of the hybrid joints and their respective sub-components, additional tests are carried out on simply bonded and simply bolted specimens. The high rate characterization was performed with a Split Hopkinson Tension Bar. The main challenges for these tests are the relatively large specimen size and complex specimen geometry needed to properly characterize the joint behavior, which both are in contradiction with the assumptions of the classical Split Hopkinson Bar-analysis. In this paper we describe an approach to solve these challenges based on an elastic wave analysis of the system.
Weidlich A, Künzel T, Klumpp F
Bidding Strategies for Flexible and Inflexible Generation in a Power Market Simulation Model
2018 1st International Workshop on Energy Market Engineering ACM e-Energy 2018, Band: 1, Nummer: 1, Seiten: 532 - 537
KurzfassungThis paper presents an electricity market simulation model that focuses on the distinction between flexible and inflexible generation, and formulates bidding strategies for capacities of either type. Bid formulation for flexible power plants, storage and demand response units at a balancing power market and an energy exchange market are described, and exemplary results from the simulation model are presented. It is shown that the simulation model can realistically reproduce market outcomes for the example of the German market zone, and that it can also simulate negative market prices. Results reveal that power plants could be deployed in a more flexible manner than they are currently done in actual market operation, where larger variations of output are avoided especially for nuclear and lignite-fired power plants. The model can be used for analyzing future energy scenarios of high shares of variable renewable energy (VRE), and help answering research questions related to the required system flexibility for balancing out VRE fluctuations.
Watson, Erkai, Maas, Hans-Gerd, Schaefer, Frank, Hiermaier, Stefan
Trajectory based 3D fragment tracking in hypervelocity impact experiments
2018 Symposium "Towards Photogrammetry 2020"/Riva del Garda ISPRS, 2018 (The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2, Band: XLII-2
KurzfassungCollisions between space debris and satellites in Earth’s orbits are not only catastrophic to the satellite, but also create thousands of newfragments, exacerbating the space debris problem. One challenge in understanding the space debris environment is the lack of data onfragmentation and breakup caused by hypervelocity impacts. In this paper, we present an experimental measurement technique capableof recording 3D position and velocity data of fragments produced by hypervelocity impact experiments in the lab. The experimentalsetup uses stereo high-speed cameras to record debris fragments generated by a hypervelocity impact. Fragments are identified andtracked by searching along trajectory lines and outliers are filtered in 4D space (3D + time) with RANSAC. The method is demonstratedon a hypervelocity impact experiment at 3.2 km/s and fragment velocities and positions are measured. The results demonstrate thatthe method is very robust in its ability to identify and track fragments from the low resolution and noisy images typical of high-speedrecording.
Tucher Nico, Höhn Oliver, Bläsi Benedikt, Goldschmidt Jan Christoph
Advanced module optics of textured perovskite silicon tandem solar cells
2018 SPIE Photonics Europe, 2018, Strasbourg, France Photonics for Solar Energy Systems VII,, Band: 10688, Seiten: 1068805-1 - 1068805-5
KurzfassungPerovskite silicon tandem solar cells can overcome the efficiency limit of single junction silicon solar cells. Optical modeling plays a crucial role for the device optimization but it becomes complex if optically thin and thick layers as well as interface textures, such as random pyramids, are involved. Within this work, the OPTOS simulation formalism is applied in order to compare perovskite silicon tandem solar cells with planar and textured front side. Modeling the configuration with planar front side and textured rear exhibits a matched photocurrent density of 18.2 mA/cm2. For the system with textured front and planar rear side the reduced reflectance leads to a photocurrent density of 19.6 mA/cm2 although parasitic absorption in the Spiro-OMeTAD and ITO layers increases. Taking into account the full module stack in the OPTOS simulation shows an increased front side reflectance and parasitic absorption in the EVA. The difference between the resulting photocurrent densities (17.8 mA/cm2 and 18.9 mA/cm2) demonstrates the optical superiority of the investigated system with textured front side not only at cell level but also in the full module stack.

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Stevens L, Hauser H, Höhn O, Tucher N, Wellens C, Jahn R, Glaubitt W, Müller C, Bläsi B
Nanoimprinted sol-gel materials for antireflective structures on silicon solar cells
2018 SPIE Photonics Europe, 2018, Strasbourg, France
KurzfassungSilicon solar cells are typically textured by means of wet chemical etching in order to enhance absorption. Within this work, we apply an optically functional layer onto a planar silicon surface. This layer is made of a high refractive index sol-gel material and can be patterned by nanoimprint lithography (NIL). In first experiments, we investigated various sol-gel based TiO2 precursors and evaluated their refractive index as well as the possibility to apply them in NIL. The refractive index was determined to be up to 2.25 using ellipsometry. This result was achieved with a solution composed of amorphous TiO2 precursors mixed with ethanol and 1,5-pentanediol. The topography of the patterned TiO2 layers were investigated using an atomic force microscope (AFM) and a scanning electron microscope (SEM) revealing a period of 1 μm and a pattern depth of 60 nm after sintering. Furthermore, optical modeling was used to optimize the structure parameters in order to minimize the weighted reflectance of an encapsulated silicon solar cell

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Hoschke, Klaus, Pfaff, Aron, Fleig, Luisa, Bierdel, Marius, Jaecklein, Martin, Riedel, Werner, Hiermaier, Stefan
A parametric mesostructural approach for robust design of additive manufacturing parts
2018 Fraunhofer Direct Digital Manufacturing Conference (DDMC)/Berlin Fraunhofer Direct Digital Manufacturing Conference DDMC 2018, Band: 1
KurzfassungAdditive Manufacturing (AM) allows for production of potentially complex design solutions and motivates the use of Structural Optimization tools in product development to chase the structural limit of a design problem and its solution concept. Scratching on the limits of the material strength, design solutions can lack robustness concerning simplifications in model assumptions and uncertainties. However, the design freedom with AM can also actively be used to enhance robustness and reliability of solutions. To this end, an approach is presented that introduces Parametric Mesostructures into selective areas of the Additive Design. Structural members and coherent mechanical characteristics of these mesostructures can significantly reduce local stress peaks and can account for uncertainties, e.g. direction of load application. Their design is motivated by Structural Optimization and analysis results. Implementation of the approach is demonstrated and discussed on the example of a structural aircraft component.
Ganzenmüller, Georg, Langhof, Timo, Hiermaier, Stefan
A constant acoustic impedance mount for sheet-type specimens in the tensile Split-Hopkinson Bar
2018 International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading (DYMAT) <12, 2018, Arcachon> Les Ulis: EDP Sciences, 2018 (EPJ Web of Conferences 183) ISBN: 978-2-7598-9053-8 Art. 02064, 4 S., Seite: 4
KurzfassungThis paper addresses a problem well-known amongst practitioners of the Split-Hopkinson Tension Bar method: attaching a flat test specimen made from sheet material to the cylindrical input-and output bars. To date, slotting the bar ends and gluing the specimens into these ends with high-strength adhesives is the gold standard. However, this approach is not universally applicable because some materials are difficult to bond, and the adhesion surface is limited by the bar diameter, meaning that only small width specimens can be tested. In contrast, the hitherto published mechanical clamping mechanisms typically introduce excessive additional mass into the Split-Hopkinson system which detrimentally affects wave propagation and thus causes errors in the stress-strain signals. We circumvent this problem by designing a mechanical clamping device which has the same acoustic impedance as the bar material and is suitable to securely attach specimens with a width larger than the bar diameter. The benefits of our new clamping device are demonstrated by reporting tensile stress-strain data for Polycarbonate at high strain rates. The data is free from unwanted oscillations and enables accurate determination of dynamic strength and stiffness.
Hoschke, Klaus, Pfaff, Aron, Fleig, Luisa, Bierdel, Marius, Jaecklein, Martin, Riedel, Werner, Hiermaier, Stefan
A parametric mesostructural approach for robust design of additive manufacturing parts
2018 Fraunhofer Direct Digital Manufacturing Conference, DDMC 2018, Fraunhofer Verlag, Stuttgart, Seite: 6
KurzfassungAdditive Manufacturing (AM) allows for production of potentially complex design solutions and motivates the use of Structural Optimization tools in product development to chase the structural limit of a design problem and its solution concept. Scratching on the limits of the material strength, design solutions can lack robustness concerning simplifications in model assumptions and uncertainties. However, the design freedom with AM can also actively be used to enhance robustness and reliability of solutions. To this end, an approach is presented that introduces Parametric Mesostructures into selective areas of the Additive Design. Structural members and coherent mechanical characteristics of these mesostructures can significantly reduce local stress peaks and can account for uncertainties, e.g. direction of load application. Their design is motivated by Structural Optimization and analysis results. Implementation of the approach is demonstrated and discussed on the example of a structural aircraft component.
Tranberg B, Schäfer M, Brown T, Hörsch J, Greiner M
Flow-based analysis of storage usage in a low-carbon European electricity scenario
2018 15th International Conference on the European Energy Market (EEM), 2018

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Bläsi Benedikt, Höhn Oliver, Hauser Hubert, Cariou Romain, Benick Jan, Feldmann Frank, Beutel Paul, Lackner David, Hermle Martin, Siefer Gerald, Glunz Stefan, Bett Andreas, Dimroth Frank, Tucher Nico, Wehrspohn Ralf, Sprafke Alexander
Photonic structures for III-V//Si multijunction solar cells with efficiency >33%
2018 SPIE, Seite: 2
KurzfassungSilicon based multi-junction solar cells are a promising option to overcome the theoretical efficiency limit of a silicon solar cell (29.4%). With III-V semiconductors, high bandgap materials applicable for top cells are available. For the application of such silicon based multi-junction devices, a full integration of all solar cell layers in one 2-terminal device is of great advantage. We realized a triple-junction device by wafer-bonding two III-V-based top cells onto the silicon bottom cell. However, in such a series connected solar cell system, the currents of all sub-cells need to be matched in order to achieve highest efficiencies. To fulfil the current matching condition and maximise the power output, photonic structures were investigated. The reference system without photonic structures, a triple-junction cell with identical GaInP/GaAs top cells, suffered from a current limitation by the weakly absorbing indirect semiconductor silicon bottom cell. Therefore rear side diffraction gratings manufactured by nanoimprint lithography were implemented to trap the infrared light and boost the solar cell current by more than 1 mA/cm2. Since planar passivated surfaces with an additional photonic structure (i.e. electrically planar but optically structured) were used, the optical gain could be realized without deterioration of the electrical cell properties, leading to a strong efficiency increase of 1.9% absolute. With this technology, an efficiency of 33.3% could be achieved.

2017

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Watson, Erkai, Gulde, Max, Schaefer, Frank, Hiermaier, Stefan
Optical fragment tracking in hypervelocity impact experiments
2017 International Astronautical Congress (IAC)/Adelaide 68th International Astronautical Congress (IAC 2017): Unlocking Imagination, Fostering Innovation and Strengthening Security, Band: 6, Seiten: 3585 - 3592
KurzfassungIn-orbit impacts between satellites and space debris lead to varying degrees of fragmentation, ranging anywhere from minor damage to complete breakups. In this paper, we describe an experimental measurement approach for studying the fragmentation effects of hypervelocity impact in the laboratory. We investigate hypervelocity impacts on a thin aluminum bumper plates and track individual fragments in the debris clouds with an innovative algorithm that bases matches on trajectories instead of features. The experimental setup involves recording the debris cloud fragments illuminated by a thin laser plane with a high-speed video camera. The image sequence is analyzed, yielding spatio-temporal information about each fragment in the debris cloud. This allows individual fragment size and velocity information, to directly measured.
F. Staab, F. Balle
Ultrasonic Torsion Welding of Aging Resistant Al/CFRP Joints - Concepts, Mechanical and Microstructural Properties
2017 21st Symposium on Composites, Bremen Key Engineering Materials, Trans Tech Publications, Band: 742, Seiten: 395 - 400
Schäfer M, Schwenk-Nebbe LJ, Hörsch J, Tranberg B, Greiner M
Allocation of nodal costs in heterogeneous highly renewable European electricity networks
2017 14th International Conference on the European Energy Market (EEM), 2017, Seiten: 1 - 6
KurzfassungWe consider a simplified model of a future European electricity network with a high share of renewable generation. In a cost optimal design of such a system, most of the renewable generation capacity is placed at locations with favorable weather conditions, that is for instance onshore wind in countries bordering the North Sea and solar PV in South European countries. Countries with less favorable renewable generation conditions benefit from this capacity by importing the respective electricity as power flows through the transmission grid. Using flow tracing techniques, we disentangle the emerging pattern of imports and exports and assign shares of the distributed generation capacity in the European system to the countries which actually make use of them. This procedure yields nodal levelized costs, which incorporate both internal and external generation costs associated with the electricity consumption in a country.
Künzel T, Klumpp F, Weidlich A
Modellgestützte Analyse der Bereitstellung von Flexibilität auf dem Strom- und Regelleistungsmarkt in Deutschland
2017 Optimierung in der Energiewirtschaft VDI-Berichte, Band: 2303, Seiten: 31 - 46
Kökbudak Gamze, Müller Ralph, Feldmann Frank, Fell Andreas, Turan Raşit, Glunz Stefan, Kökbudak G., Müller R., Feldmann F., Fell A., Turan R., Glunz S.
On the Determination of the Contact Resistivity for Passivating Contacts Using 3D Simulations
2017
KurzfassungBesides surface passivation, a low contact resistivity is one of the most important requirements of passivating contacts in order to achieve good carrier selectivity. In this work, different methods to determine the contact resistivity were performed and compared using a passivating contact structure consisting of poly silicon on a thin silicon oxide. As the traditional 1D Transmission Line Model (TLM) includes many assumptions that are not valid for complicated structures and even the application of the analytical 2D TLM is limited, especially for very low contact resistivity values, 3D numerical simulations with Quokka3 were carried out to accurately model passivating contact structures and determine the contact resistivity by comparison to electrical measurements. The investigated sample showed both, good passivation quality with implied open-circuit voltage iVoc of 716 mV together with a low specific contact resistivity of 0.21 mΩ·cm2 as extracted from the numerical simulations. Using our method, it is possible to distinguish the sources of the contact resistivity. A fraction of 0.11 mΩ·cm2 could be attributed to the interface between metal & poly-Si layer and 0.10 mΩ·cm2 results from the interface between poly-Si layer & bulk.
Dlugosch, Michael, Spiegelhalter, Bastian, Soot, Thomas, Lukaszewicz, Dirk, Fritsch, Jens, Hiermaier, Stefan
Potentials of optical damage assessment techniques in automotive crash-concepts composed of FRP-steel hybrid material systems
2017 12th International Conference on Damage Assessment of Structures, DAMAS 2017. Proceedings, IOP, London, Seite: Art. 012044, 13
KurzfassungWith car manufacturers simultaneously facing increasing passive safety and efficiency requirements, FRP-metal hybrid material systems are one way to design lightweight and crashworthy vehicle structures. Generic automotive hybrid structural concepts have been tested under crash loading conditions. In order to assess the state of overall damage and structural integrity, and primarily to validate simulation data, several NDT techniques have been assessed regarding their potential to detect common damage mechanisms in such hybrid systems. Significant potentials were found particularly in combining 3D-topography laser scanning and X-Ray imaging results. Ultrasonic testing proved to be limited by the signal coupling quality on damaged or curved surfaces.
Niewelt T., Schindler F., Kwapil W., Eberle R., Schön J., Schubert M.
Understanding the Light-Induced Degradation at Elevated Temperatures: Similarities between Multicrystalline and Floatzone p-Type Silicon.8 pages / 33rd European Photovoltaic Solar Energy Conference and Exhibition; 218-225
2017
KurzfassungThis paper discusses degradation phenomena in crystalline silicon. We present new investigations of the light‐ and elevated temperature‐induced degradation of multicrystalline silicon. The investigations provide insights into the defect parameters as well as the diffusivity and solubility of impurity species contributing to the defect. We discuss possible defect precursor species and can rule out several metallic impurities. We find that an involvement of hydrogen in the defect could explain the characteristic observations for light‐ and elevated temperature‐induced degradation. Furthermore, we demonstrate analogies to the light‐induced degradation mechanisms at elevated temperatures observed in floatzone silicon, where several experimental results also indicate an involvement of hydrogen in the defect. Based on the similarities between multicrystalline and floatzone silicon, we suggest that both degradation phenomena might be caused by the same or similar defects. As we do not expect large concentrations of metals in floatzone silicon, we suggest that complexes of hydrogen and a species introduced during crystal growth might cause both degradation phenomena.

2016

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Ilchmann, C, Hess, S, Klatt, M
Open Source Modeling of Solar Process Heat Systems
2016 4th South African Solar Energy Conference
Hess, S, Beukes, H, Smith, G, Dinter, F
Solar Process Heat for South African Sugar Mills
2016 Proceedings of EuroSun 2016 / Palma de Mallorca
Nagel H, Kamp M, Eberlein D, Kraft A, Bartsch J, Glatthaar M, Glunz S
Enabling solderability of PVD Al rear contacts on high-efficiency crystalline silicon solar cells by wet chemical treatment
2016 32nd EU PVSEC, Seiten: 48 - 52
Dlugosch, M., Ihle, J., Lukaszewicz, D., Fritsch, J., Hiermaier, S.
Experimental investigation of automotive components consisting of hybrid FRP-metal material systems under crash loading
2016 2. Internationale Konferenz Euro Hybrid - Materials and Structures 2016. Proceedings, Institut fuer Verbundwerkstoffe -IVW-, Kaiserslautern, Kaiserslautern, Seiten: 63 - 68
KurzfassungIn the course of a strong trend towards automotive material diversification, hybrid material systems could offer solutions to design lightweight body-in-white structures particularly subject to crash loads in order to meet the demands of both ambitious efficiency goals and increasingly strict vehicle safety requirements. Hybrid material systems consisting of glass- and carbon fiber reinforced plastics and sheet steel are tested under axial impact loading and analyzed regarding their qualitative behavior and relevant crash metrics. The study shows the complex behavior of those material systems and the interaction between the material phases resulting in a complex system of parameter effects and interdependencies. Generally, the hybrid specimens studied indicated their applicability in automotive crash structures by exhibiting comparable results to pure FRP materials while simultaneously being potentially more compatible and cost efficient.
Bivour Martin, Temmler Jan, Zähringer Florian, Glunz Stefan, Hermle Martin
High work function metal oxides for the hole contact of silicon solar cells
2016 43rd IEEE Photovoltaic Specialists Conference (PVSC), Seiten: 215 - 220
Klomfass, A., Stolz, A., Hiermaier, S.
Improved explosion consequence analysis with combined CFD and damage models
2016 15th International Symposium on Loss Prevention and Safety Promotion in the Process Industries 2016. Proceedings, AIDIC, Mailand, Seiten: 109 - 114
KurzfassungThe most-widely used approach to explosion consequence analysis is the classical engineering method based on the combination of TNT equivalence, scaled distances and overpressure-based damage levels. This approach rests on established and easily comprehensible elements and permits a fast assessment of explosion consequences. There are however several limitations inherent in this approach. In contrast, a simulation-based approach using computational fluid dynamics (CFD) and structural dynamics (CSD) methods permits an analysis with a high level of detail regarding both the prediction of the explosive loads and the caused damage. This comes at the cost of complex simulation models which require expert knowledge, intense validation and a high computational effort. To bridge the gap between the classical simplified approach and the CFD/CSD based methods, we have developed a specialized CFD tool, the APOLLO Blastsimulator, with a built-in library of experimentally validated damage models and blast-injury models suitable for an improved explosion consequence analysis. The high resolution CFD tool uses globally and locally adaptive Cartesian grids and includes models for TNT detonations as well as gas detonations. The built-in damage models are based on experimentally validated single-degree-of-freedom (SDOF) representations of structural components. This paper gives a brief review on the classical approaches and their limitations and an overview on the concepts used in the APOLLO Blastsimulator and the SDOF damage models. For an exemplary explosion scenario the results obtained with different explosive source and damage models are compared.
Klomfass, A., Stolz, A., Hiermaier, S.
Improved explosion consequence analysis with combined CFD and damage models
2016 15th International Symposium on Loss Prevention and Safety Promotion in the Process Industries 2016. Proceedings, AIDIC, Mailand, Seiten: 109 - 114
KurzfassungThe most-widely used approach to explosion consequence analysis is the classical engineering method based on the combination of TNT equivalence, scaled distances and overpressure-based damage levels. This approach rests on established and easily comprehensible elements and permits a fast assessment of explosion consequences. There are however several limitations inherent in this approach. In contrast, a simulation-based approach using computational fluid dynamics (CFD) and structural dynamics (CSD) methods permits an analysis with a high level of detail regarding both the prediction of the explosive loads and the caused damage. This comes at the cost of complex simulation models which require expert knowledge, intense validation and a high computational effort. To bridge the gap between the classical simplified approach and the CFD/CSD based methods, we have developed a specialized CFD tool, the APOLLO Blastsimulator, with a built-in library of experimentally validated damage models and blast-injury models suitable for an improved explosion consequence analysis. The high resolution CFD tool uses globally and locally adaptive Cartesian grids and includes models for TNT detonations as well as gas detonations. The built-in damage models are based on experimentally validated single-degree-of-freedom (SDOF) representations of structural components. This paper gives a brief review on the classical approaches and their limitations and an overview on the concepts used in the APOLLO Blastsimulator and the SDOF damage models. For an exemplary explosion scenario the results obtained with different explosive source and damage models are compared.
Künzel T, Weidlich A
Methodik zur Quantifizierung der Grenzkosten flexibler Systemkomponenten
2016 3. Konferenz Zukünftige Stromnetze für Erneuerbare Energien, Berlin , Seiten: 110 - 114
Goldschmidt Jan, Bett Alexander, Bivour Martin, Bläsi Benedikt, Eisenlohr Johannes, Kohlstädt Markus, Lee Seunghun, Mastroianni Simone, Mundt Laura, Mundus Markus, Ndione Paul, Reichel Christian, Schubert Martin, Schulze Patricia, Tucher Nico, Veit Clemens, Veurman Welmoed, Wienands Karl, Winkler Kristina, Würfel Uli, Glunz Stefan, Hermle Martin
Monolithic perovskite silicon tandem solar cells with advanced optics
2016 Washington, D.C. Light, Energy and the Environment. Optical Nanostructures and Advanced Materials for Photovoltaics 2016, OSA
Haering, Ivo, Scharte, Benjamin, Hiermaier, Stefan
Towards a novel and applicable approach for Resilience Engineering
2016 6th International Disaster and Risk Conference, IDRC 2016. Extended Abstracts, GRF, Davos, Seiten: 272 - 276
KurzfassungResilience Engineering can provide society and its critical infrastructure and systems with means, methods and technologies to overcome disruptions with as less harm as possible. In this context it is of utmost importance to identify ways to strengthen the adaptive capacity of up to complex socio technical systems. We try to establish Resilience Engineering as away of thinking that enables engineers to use their scientific expertise, creative ingenuity and help society to develop tools to handle all kinds of adverse events properly - from critical system disruptions, natural disasters, global terrorism to large-scale infrastructure failure. For that purpose, we suggest to deliberately limit the scope of Resilience Engineering towards engineering, i.e. mainly technological solutions, in contrast to the main body of Resilience Engineering literature. By that we try to pave the way for the next generation of engineers dealing with the extension from risk analysis and management towards resilience thinking. In short, Resilience Engineering means preserving critical functionality, ensuring graceful degradation and enabling fast recovery of systems with the help of engineered generic capabilities as well as customized technological solutions when the systems witness problems, unexpected disruptions or unexampled events. One central aspect of Resilience Engineering is the ability to quantify and measure resilience. Only adequate and valid indicators will give us the chance for comparatively and absolutely analyzing various systems with respect to their specific resilience. Finally, we need to be able to develop advanced methods for modelling and simulating, in particular for complex systems and their resilience towards adverse events. The presentation will hint at opportunities and research necessities for developing a new and integrated approach to model, simulate and improve the resilience of complex, interdependent, sociotechnical systems.

2015

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Hess, S
Technologies and Perspectives for Solar Water Heating and Solar Process Heat in Southern Af-rica
2015 1st International Renewable Energy Symposium IRES / Windhoek
Hess, S
Stationary Booster Reflectors for Solar Thermal Process Heat Generation
2015 3rd South African Solar Energy Conference /Skukuza
Cadoni E, Couque H, Hiermaier S
DYMAT 2015, 11th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading
2015 EDP Sciences, Les UlisEPJ Web of Conferences 94.2015, EDP Sciences, Les Ulis
Hiermaier, S.
Foreword. DYMAT 2015 - 11th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading
2015 DYMAT 2015, 11th International Conference on the Mechanical and Physical Behaviour of Materials under Dynamic Loading, EDP Sciences, Les Ulis, Seite: Art. 00001, 1
Ganzenmueller, G., Hiermaier, S., May, M.
Improvements to the prototype micro-brittle model of peridynamics
2015 Meshfree Methods for Partial Differential Equations VII, Springer International Publishing, Cham, Seiten: 163 - 183
KurzfassungThis paper assesses the accuracy and convergence of the bond-based Peridynamic model with brittle failure, known as the prototype micro-brittle (PMB) model. We investigate the discrete equations of this model, suitable for numerical implementation. It is shown that the widely used discretization approach incurs rather large errors. Motivated by this observation, a correction is proposed, which significantly increases the accuracy by cancelling errors associated with the discretization. As an additional result, we derive equations to treat the interactions between differently sized particles, i.e., a non-homogeneous discretization spacing. This presents an important step forward for the applicability of the PMB model to complex geometries, where it is desired to model interesting parts with a fine resolution (small particle spacings) and other parts with a coarse resolution in order to gain numerical efficiency. Validation of the corrected Peridynamic model is performed by comparing longitudinal sound wave propagation velocities with exact theoretical results. We find that the corrected approach correctly reproduces the sound wave velocity, while the original approach severely overestimates this quantity. Additionally, we present simulations for a crack growth problem which can be analytically solved within the framework of Linear Elastic Fracture Mechanics Theory. We find that the corrected Peridynamics model is capable of quantitatively reproducing crack initiation and propagation.
Ledford Noah, Paul Hanna, Ganzenmueller Georg, May Michael, Hoefemann Matthias, Otto Manuel, Petrinic Nikica
Investigations on specimen design and mounting for Split Hopkinson Tension Bar (SHTB) experiments
2015 17 AVE DU HOGGAR PARC D ACTIVITES COUTABOEUF BP 112, F-91944 CEDEX A, FRANCE DYMAT 2015 - 11TH INTERNATIONAL CONFERENCE ON THE MECHANICAL AND PHYSICAL BEHAVIOUR OF MATERIALS UNDER DYNAMIC LOADING, E D P SCIENCES, Band: 94
KurzfassungSplit Hopkinson Tension Bar (SHTB) experiments can be used to test the material behavior with high strain rates in tension loading. The influence of the specimen mounting and the specimen design on the test results was investigated. Three mounting methods were tested. The best signal is achieve using a mounting based on form fit. The three tested specimen designs all lead to a valid fracture behavior, but result in a different local strain rate.
Dlugosch, M., Lukaszewicz, D., Fritsch, J., Hiermaier, S.
Mechanical characterization of hybrid material systems consisting of sheet metal and advanced composites
2015 20th International Conference on Composite Materials, ICCM 2015. Proceedings. Online resource, Seiten: Paper 4213 - 5, 16
KurzfassungStrip-shaped hybrid coupon specimens comprised of steel and glass/carbon fiber reinforced plastics are tested under quasistatic tension and 3-point-bending. The effects of major material and design parameters (steel and fiber type, laminate thickness and layup) on the stiffness, strength and the specific energy absorption are assessed. Furthermore, hybrid mechanisms resulting from the mutual interaction of both constituent materials are presented. Although anticipated effects on the hybrid specimens' stiffness and strength are widely confirmed, the fiber type for example exhibits a distinctly smaller impact than expected. The specimens' loading and failure behavior is rather dominated by the type of steel and its characteristics. Thus, glass fiber reinforced hybrid variants generally keep up with carbon fiber reinforced hybrid variants in terms of mechanical properties. Considering the difference in price, this is of particular interest for hybrid mid or high volume crash structural applications. As hybrid mechanism, a distinct extension of the maximum strain is observed for both composites (up to 48 %) and steel (up to 23 %) when joined in a hybrid specimen and tested under tensile loads. Furthermore, having composites on the rather pressure loaded side in 3-point-bending results in a 26 %-increase in mass specific energy absorption (compared to reverse loading) due to an enhanced composite failure mode and the stabilizing effect of the steel strip.
Dlugosch, M., Fritsch, J., Lukaszewicz, D., Hiermaier, S.
New method to analyze numerical crash simulation data to assess the suitability of hybrid composite structures in automotive applications
2015 30. American Society for Composites 2015. Proceedings. CD-ROM, DEStech Publications, Lancaster, Pa., Seite: Paper 1554, 15
KurzfassungIn order to enhance development processes for multi material vehicle architecture concepts involving composites or hybrid composite-metal material systems a method is presented that aims to rationalize engineering judgements by means of quantifiable criteria for the suitability of a certain hybrid material system for a particular structural application. A number of significant crash load cases for a structure is considered simultaneously by superimposing the output data of several numerical crash simulations and defining criteria to qualify the suitability of a particular hybrid material system. The work introduced here focusses on the analysis of the global anisotropy of the crash loading situation as an indicator for a rather composite- or metal-intensive hybrid material system. The definition of the anisotropy criterion and the implementation of the method into the development infrastructure of automotive engineering is presented. A first step validation using simple flat coupon specimen simulations shows reasonable results and proves the applicability of the method.
Nagel H, Glatthaar M, Glunz S
Quantitative assessment of the local leakage current in PV modules for degradation prediction
2015 31st EU PVSEC, Seiten: 1825 - 1829
Glunz S, Feldmann F, Richter A, Bivour M, Reichel C, Steinkemper H, Benick J, Hermle M
The irresistible charm of a simple current flow pattern – 25% with a solar cell featuring a full-area back contact
2015 31st EU PVSEC, Seiten: 259 - 263
Hackel, T., Stein, D., Maindorfer, I., Lauer, M., Reiterer, A.
Track Detection in 3D Laser Scanning Data of Railway Infrastructure
2015 IEEE International Instrumentation and Measurement Technology Conference

2014

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Platzer, W, Helmke A, Hess, S
Climate Relevance in Solar Process Heat System Optimization - Case Studies with Different Temperatures and Load Profiles
2014 Proceedings of the 2nd South African Solar Energy Conference / Port Elizabeth
Benick J, Steinhauser B, Müller R, Bartsch J, Kamp M, Mondon A, Richter A, Hermle M, Glunz S
High efficiency n-type PERT and PERL solar cells
2014 40th IEEE Photovoltaic Specialists Conference (PVSC) 2014, Seiten: 3637 - 3640
Hiermaier S
Hopkinson Centenary Conference 2014
2014 Omniprint, Gundelfingen, Omniprint, Gundelfingen
Nagel H, Saint-Cast P, Glatthaar M, Glunz S
Inline processes for the stabilization of p-type crystalline Si solar cells against potential-induced degradation
2014 29th EU PVSEC, Seiten: 2351 - 2355
Reichel C, Feldmann F, Müller R, Moldovan A, Hermle M, Glunz S
Interdigitated back contact silicon solar cells with tunnel oxide passivated contacts formed by ion implantation
2014 29th EU PVSEC, Seiten: 487 - 491
Gautrein A, Schmiga C, Glatthaar M, Tremel W, Glunz S
Nanometallic silver inks for metallization of ITO-coated silicon solar cells: Influence of organic components
2014 29th EU PVSEC, Seiten: 1277 - 1281
Binder S, Schmiga C, Glatthaar M, Glunz S
Optimized aerosol jet printed silver contacts on lowly doped phosphorus and boron emitters
2014 29th EU PVSEC, Seiten: 1363 - 1367
Mondon A, Bartsch J, Kamp M, Brand A, Steinhauser B, Bay N, Horzel J, Glatthaar M, Glunz S
Plated nickel-copper contacts on c-Si: From microelectronic processing to cost effective silicon solar cell production
2014 29th EU PVSEC, Seiten: 1286 - 1291
Rauer M, Steinkemper H, Schmiga C, Glatthaar M, Glunz S
Recombination characteristics of p+ regions alloyed from screen-printed aluminum pastes containing boron additives
2014 29th EU PVSEC, Seiten: 1420 - 1423

2013

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Feldmann F, Bivour M, Reichel C, Hermle M, Glunz Stefan
A passivated rear contact for high-efficiency n-type silicon solar cells enabling high VocS and FF\textgreater82%: Proceedings of the 29th EUPVSEC, Paris, France
2013 28th EU PVSEC
Hiermaier, S.
Integrated experimental-numerical characterization of geological materials under shock and impact
2013 Rock Dynamics and Applications. State of the Art, CRC Press, Hoboken, Seiten: 71 - 76
KurzfassungScientific investigation of transient processes and engineering design of structures for dynamic loading conditions are still a great challenge. Other than quasi-static loading conditions a dynamic application of loads by impact or blast leads to additional effects that enhance the complexity of the thermo-mechanical material behavior. They can be reduced to two basic phenomena: first, the strain rate dependent change of mechanical behavior and, secondly, the evolution and propagation of shock waves. In order to understand the structural behavior under transient loading conditions, the involved materials need to be characterized by material tests. Mathematical formulations are needed for the description of both the strain rate dependent deviatoric behavior and the non-linear Equation of State responsible for the shock wave formation. Implemented into numerical codes these constitutive equations allow for a predictive simulation of the structural behavior. Sometimes nume rical simulation itself can be used to derive material properties. This is the case when for example the material is composed of two or more constituents for which the individual thermo-mechanical properties are known. Modeling the composite material as specimens and application of loads that may be outside the load types applicable in experiments leads to additional results not achievable in a pure experimental approach. Therefore, an integrated experimental-numerical approach for the characterization of materials under transient loading conditions is more and more preferred if predictive capabilities are needed for the highly complex phenomena observed in the related structural applications of interest.
Durr, N., Sauer, M., Gueldemeister, N., Wuennemann, K., Hiermaier, S.
Mesoscale Investigation of Shock Wave Effects in Dry and Water-saturated Sandstone
2013 12th Hypervelocity Impact Symposium, HVIS 2012. Proceedings, Elsevier, Amsterdam
KurzfassungIn this paper, the behavior of natural sandstone under hypervelocity impact is investigated numerically. Sandstone essentially consists of cemented quartz grains, it can be generally considered as a polygranular structure with air or water-filled pores. In order to study the influence of pores and water filling on the behavior of sandstone under shock loading, a numerical investigation at the mesoscale is performed. We explicitly resolve pores and the closure of pores in a homogeneous and isotropic quartz matrix. The quartz matrix is described with an equation of state and a strength model; the pore geometry is simplified. Two-dimensional planar shock simulations are conducted in order to analyze effects of quartz strength and water-saturation on pore crushing. Averaging is used to perform a macroscale analysis of the dependencies of pressure and shock velocity on particle velocity. The simulation results shall enhance the basis for the development of accurate macroscale sandstone models that take the water content into account.
Durr, N., Sauer, M., Gueldemeister, N., Wuennemann, K., Hiermaier, S.
Mesoscale Investigation of Shock Wave Effects in Dry and Water-saturated Sandstone
2013 12th Hypervelocity Impact Symposium, HVIS 2012. Proceedings, Elsevier, Amsterdam
KurzfassungIn this paper, the behavior of natural sandstone under hypervelocity impact is investigated numerically. Sandstone essentially consists of cemented quartz grains, it can be generally considered as a polygranular structure with air or water-filled pores. In order to study the influence of pores and water filling on the behavior of sandstone under shock loading, a numerical investigation at the mesoscale is performed. We explicitly resolve pores and the closure of pores in a homogeneous and isotropic quartz matrix. The quartz matrix is described with an equation of state and a strength model; the pore geometry is simplified. Two-dimensional planar shock simulations are conducted in order to analyze effects of quartz strength and water-saturation on pore crushing. Averaging is used to perform a macroscale analysis of the dependencies of pressure and shock velocity on particle velocity. The simulation results shall enhance the basis for the development of accurate macroscale sandstone models that take the water content into account.
Saint-Cast P, Nagel H, Wagenmann D, Schön J, Schmitt P, Reichel C, Glunz Stefan, Hofmann M, Rentsch J, Preu R
Potential induced degradation: Understand and avoid PID on the cell level
2013 28th EU PVSEC
Janz S, Schnabel M, Löper P, Summonte C, Canino M, López-Vidrier J, Hernández S, Garrido B, Glunz Stefan
Processing and characterisation of tandem solar cells from crystalline silicon materials
2013 28th EU PVSEC
Glunz Stefan, Lee J, Rein S
Strategies for improving the efficiency of Cz-silicon solar cells
2013 28th EU PVSEC, Seiten: 201 - 204

2012

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Fahr, S, Kramer, K, Mehnert, S, Hess, S
Solar Keymark certification for concentrating collectors - Comparing the quasi-dynamic and the steady-state method of EN 12975-2:2006-A1:2010
2012 Proceedings of Solar PACES /Marrakesh
Hess, S, Oliva, A, Hermann, M, Stryi-Hipp, G, Hanby, V
Solar Process Heat – System Design for Selected Low-temperature Applications in the Industry
2012 proceedings of the ISES Solar World Congress /Kassel.
Hess, S, Oliva, A, Helmke, A, Stryi-Hipp, G, Platzer, W
Solar Process Heat – System Design for Selected Low-temperature Applications in the Industry
2012 Proceedings of the 22. OTTI-Symposium Thermische Solarenergie / Bad Staffelstein.
Helmke, A, Kumar, DS, Hess, S, Stryi-Hipp, G
Solare Prozesswärme in Indien – Markterschließung und Systemtechnik
2012 Proceedings of the 23. OTTI-Symposium Thermische Solarenergie / Bad Staffelstein
Hiermaier, S., Kilchert, S., May, M.
Modellierung des Einflusses von Unregelmaessigkeiten in der Mikrostruktur auf das Versagen von UD-Composites
2012 Berechnung und Simulation - Anwendungen, Entwicklungen, Trends, NAFEMS Deutschland, Bernau am Chiemsee
Steinhauser, M., Ganzenmueller, G., Hiermaier, S.
Multiscale modeling and simulation of shock-wave impact failure in hard and soft matter
2012 28th International Symposium on Shock Waves 2011. Vol.1, Springer, Berlin, Seiten: 803 - 808
KurzfassungUnderstanding the mechanisms of failure in materials on various length- and time scales is a prerequisite for the design of new materials with desired superior properties such as high toughness or strength. On the macroscopic scale, many materials such as concrete or ceramics may be viewed as being homogeneous; however, on the scale of a few microns these materials often exhibit an inhomogeneous polyhedral granular structure which is known to influence its macroscopic mechanical and optical properties, see e.g. Steinhauser [1].
Bartsch J, Mondon A, Kamp M, Kraft A, Wendling M, Wehkamp N, Jawaid M, Lorenz A, Clement F, Schetter C, Glatthaar M, Glunz Stefan
Progress with multi-step metallization processes featuring copper as conducting layer at Fraunhofer ISE
2012 27th EU PVSEC, Seiten: 604 - 607
Schröer S, Bivour M, Schön J, Hermle M, Glunz Stefan
Reduction of absorption losses and efficiency gains by investigating amorphous/crystalline SHJ rear emitter solar cells
2012 27th EU PVSEC, Seiten: 759 - 762
Schmiga C, Rauer M, Rüdiger M, Glatthaar M, Glunz Stefan
Status and perspectives on n-type silicon solar cells with aluminium-alloyed rear emitter
2012 27th EU PVSEC, Seiten: 915 - 918
Mayer C, Dänekas C, Rohjans S, Breuer A, Theisen T, Drzisga T, König A, Luhmann T, Stadler M, Maerten M, Weidlich A
Technologische Migrationspfade in das Smart Grid
2012 VDE Kongress
Terheiden B, Horbelt R, Schiele Y, Seren S, Ebser J, Hahn G, Morrison D, Heasman K, Devenport S, Holman Z, Descoeudres A, de Wolf S, Baliff C, Saint-Cast P, Michl B, Schmiga C, Weber B, Glunz Stefan, Koentopp M
The european project 20plµS: 20 percent efficiency on less than 100µm thick industrially feasible crystalline-Si solar cells
2012 27th EU PVSEC, Seiten: 1586 - 1590
Richter A, Souren F, Schuldis D, Görtzen R, Benick J, Hermle M, Glunz Stefan
Thermal stability of spatial ALD deposited Al2O3 capped by PECVD SiNx for the passivation of lowly- and highly-doped p-type silicon surfaces
2012 27th EU PVSEC, Seiten: 1133 - 1137

2011

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Hess, S, Klemke, M, Oliva, A, Di Lauro, P, Hermann, M, Stryi-Hipp, G, Kramp, G, von Bodungen, O, Eisenmann, W, Hanby, V
Pilotanlage mit RefleC-Kollektoren: Anlagenkonzept und Monitoring-Ergebnisse
2011 Proceedings of the 21. OTTI-Symposium Thermische Solarenergie /Bad Staffelstein
Hess, S
Designing Solar Thermal Systems for Selected Industrial Applications
2011 Proceedings of the World Sustainable Energy Days, Conference Solar Process Heat / Wels.
SchĂ¤fer F, Hiermaier S
11th Hypervelocity Impact Symposium 2010. Proceedings
2011 Fraunhofer Verlag, StuttgartEpsilon. Forschungsergebnisse aus der Kurzzeitdynamik 20, Fraunhofer Verlag, Stuttgart
KurzfassungThe Hypervelocity Impact Symposium (HVIS) is a biennial event that serves as the principal forum for the discussion, interchange, and presentation of the basic physics of high- and hypervelocity impact and related scientific and technical areas. Hypervelocity impact is defined as the impact regime in which shock effects are important. The 11th HVIS was held from April 11 to 15, 2010, in Freiburg, Germany. Topics comprised: //1. Hypervelocity Phenomenology Studies //2. High-Velocity Launchers and Diagnostics //3. Spacecraft Meteoroid/Debris Shielding and Failure Analyses //4. Material Response (including EOS) //5. Fracture and Fragmentation //6. High-Velocity Penetration Mechanics and Target Response //7. Armor/Anti-Armor and Ballistic Technology //8. Analytical and Numerical Methodologies //9. Asteroid and Meteoroid Impacts, Planetary Defense Technology //The 11th HVIS attracted 150 scientists, engineers, and technical managers of academia, industry and government agencies from 15 countries. 55 presentations were given and 20 posters were presented. The related double-blind reviewed papers are all published in the Symposium’s proceedings, which are the major archival source of papers published in this field.
Peters M, Battaglia C, Aberle A, Bläsi B, Luther J, Glunz Stefan
3D optical simulation of scattering in thin film silicon solar cells
2011 26th EU PVSEC: Proceedings, Seiten: 2764 - 2767
May, M., Nossek, M., Hiermaier, S.
A multi-scale methodology for the evaluation of different fiber-matrix combinations using the generalized method of cells
2011 Seminar Progress in Simulating Composites 2011, NAFEMS Deutschland, Bernau am Chiemsee
May, M., Nossek, M., Petrinic, N., Hiermaier, S.
A new rate dependent cohesive zone model for impact applications
2011 Composites 2011, 3rd ECCOMAS Thematic Conference on the Mechanical Response of Composites. Proceedings, Leibniz Universit�t, Institut fuer Statik und Dynamik, Hannover
Jötten G, Weidlich A, Filipova-Neumann L, Schuller A
Assessment of flexible demand response business cases in the smart grid
2011 Proceedings of the 21st International Conference on Electricity Distribution CIRED, Frankfurt
Reiterer, A.
Automatisiertes Geo-Monitoring in der Ingenieurgeodäsie. Geo-Monitoring 2011 – Ein Paradigmenwechsel zur Beherrschung von Georisiken
2011 Clausthal-Zellerfeld
Müller R, Löper P, Hiller D, Gutsch S, Keding R, Reichel C, Bivour M, Hermle M, Janz S, Goldschmidt J, Zacharias M, Glunz Stefan
Calculation of the quasi fermi-level splitting in an ideal superlattice of silicon nanocrystals
2011 26th EU PVSEC: Proceedings, Seiten: 465 - 469
Kok K, Karnouskos S, Ringelstein J, Dimeas A, Weidlich A, Warmer C, Drenkard S, Hatziargyriou N, Lioliou V
Field-testing smart houses for a smart grid
2011 21st International Conference and Exhibition on Electricity Distribution CIRED, Frankfurt, Germany, Seiten: 6 - 9
Hermle M, Benick J, Bateman N, Glunz Stefan
N-type silicon solar cells with implanted emitter
2011 26th EU PVSEC: Proceedings, Seiten: 875 - 878
Eisenlohr J, Benick J, Peters M, Höhn O, Janz S, Goldschmidt J, Bläsi B, Hermle M, Glunz Stefan
Nanostructured back side reflectors for silicon solar cells
2011 26th EU PVSEC: Proceedings, Seiten: 344 - 348
Granek F, Hopman S, Kluska S, Fell A, Breitwieser M, Fleischmann C, Glatthaar M, Glunz Stefan
Progress in laser chemical processing for silicon solar cells
2011 26th EU PVSEC: Proceedings, Seiten: 1300 - 1304

2010

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Heimsath, A, Nitz, P, Hess, S
Concentrating solar collectors for process heat up to 250 °C and small scale CSP – Integrated optical design for improved performance
2010 Proceedings of EuroSun 2010 / Graz
Hess, S, Oliva, A, Di Lauro, P, Klemke, M, Hermann, M, Kramp, G, Eisenmann, W, Hanby, V
Solar Heat for Industrial Processes: RefleC-Collector Development and System Design
2010 Proceedings of EuroSun 2010 /Graz.
Hess, S, Oliva, A, Di Lauro, P, Klemke, M, Hermann, M, Stryi-Hipp, G, Kallwellis V, Kramp, G, Eisenmann, W, Hanby, V
Flachkollektor mit externen Reflektoren (RefleC): Entwicklungserfahrungen
2010 Proceedings of the 20. OTTI-Symposium Thermische Solarenergie. /, Bad Staffelstein
Jäger U, Suwito D, Benick J, Janz S, Hermle M, Glunz Stefan, Preu R
A simple laser based process for the formation of a LBSF for n-type silicon solar cells
2010 25th EU PVSEC, Seiten: 1386 - 1390
Bartsch J, Mondon A, Godejohann B.-J., Hörteis M, Glunz Stefan
Advanced front side metallization for crystalline silicon solar cells based on a fully plated contact
2010 25th EU PVSEC, Seiten: 1978 - 1983
Schmiga C, Rauer M, Rüdiger M, Meyer K, Lossen J, Krokoszinski H.-J., Hermle M, Glunz Stefan
Aluminium-doped p+ silicon for rear emitters and back surface fields: results and potentials of industrial n- and p-type solar cells
2010 25th EU PVSEC, Seiten: 1163 - 1168
Kluska S, Rodofili A, Mayer K, Fleischmann C, Granek F, Glunz Stefan
Analysis of local boron dopings formed with LCP
2010 25th EU PVSEC, Seiten: 1405 - 1409
Mayer K, Orellana Pérez T, Rostas M, Schumann M, Granek F, Glunz Stefan, Rosenfeld E, Kray D, Antoniadis H
Aromatic compounds as substitutes for 2-propanol as texturing additive in aqueous alkaline solutions
2010 25th EU PVSEC, Seiten: 2511 - 2515
Fischer S, Goldschmidt J, Krämer K, Biner D, Hermle M, Glunz Stefan
Calibrated photoluminescence measurements of the upconverter NaYF4: 20% ER3+ for silicon solar cells
2010 25th EU PVSEC, Seiten: 657 - 661
Löper P, Hiller D, Künle M, Gradmann R, Rothfelder M, Janz S, Hermle M, Zacharias M, Glunz Stefan
Carrier confinement and transport in high band gap materials with embedded Si quantum dots
2010 25th EU PVSEC, Seiten: 269 - 273
Walther S, Markovic I, Schuller A, Weidlich A
Classification of business models in the e-mobility domain
2010 Proceedings of 2nd European Conference Smart Grids and EMobility, Seiten: 20 - 21
Pysch D, Meinhardt C, Ritzau K.-U., Bivour M, Zimmermann K, Schetter C, Hermle M, Glunz Stefan
Comparison of intrinsic amorphous silicon buffer layers for silicon heterojunction solar cells deposited with different PECVD techniques
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 3570 - 3576
Bartsch J, Mondon A, Schetter C, Horteis M, Glunz Stefan
Copper as conducting layer in advanced front side metallization processes for crystalline silicon solar cells, exceeding 20% on printed seed layers
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 1299 - 1303
Reichel C, Reusch M, Granek F, Hermle M, Glunz Stefan
Decoupling charge carrier collection and metallization geometry of back-contacted back-junction silicon solar cells by using insulating thin films
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 1034 - 1038
Pysch D, Meinhardt C, Hermle M, Glunz Stefan
Development and understanding of the intrinsic and doped amorphous emitter-layer stacks for silicon heterojunction solar cells
2010 25th EU PVSEC, Seiten: 1820 - 1824
Benick J, Richter A, Li T.-T., Grant N, McIntosh K, Ren Y, Weber K, Hermle M, Glunz Stefan
Effect of a post-deposition anneal on Al\textlessinf\textgreater2\textless/inf\textgreaterO\textlessinf\textgreater3\textless/inf\textgreater/Si interface properties
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 000891 - 000896
Karnouskos S, Weidlich A, Kok K, Warmer C, Ringelstein J, Selzam P, Dimeas A, Drenkard S
Field trials towards integrating smart houses with the smart grid
2010 International Conference on Energy-Efficient Computing and Networking, Athens, Greece, Seiten: 114 - 123
Richter A, Henneck S, Benick J, Hörteis M, Hermle M, Glunz Stefan
Firing stable Al2O3/SiNx layer stack passivation for the front side boron emitter of n-type silicon solar cells
2010 25th EU PVSEC, Seiten: 1453 - 1459
Hörteis M, Benick J, Nekarda J, Richter A, Preu R, Glunz Stefan
Fundamental reactions during the formation of fired silver contacts and solar cell results
2010 2nd Workshop on Metallization Constance, Seiten: 6 - 11
Horteis M, Benick J, Nekarda J, Richter A, Preu R, Glunz Stefan
Fundamental studies on the front contact formation resulting in a 21% efficiency silicon solar cell with printed rear and front contacts
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 672 - 677
Ebong A, Rounsaville B, Cooper I, Tate K, Rohatgi A, Glunz Stefan, Horteis M, Met A, Gundermann M
High efficiency silicon solar cells with ink jetted seed and plated grid on high sheet resistance emitter
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 1363 - 1367
Saint-Cast P, Benick J, Kania D, Billot E, Richter A, Hermle M, Hofmann M, Rentsch J, Preu R, Glunz Stefan
High-efficiency p-type PERC solar cells applying PECVD ALOx layers
2010 25th EU PVSEC, Seiten: 1488 - 1491
Thomas I, Weidlich A, Johns M
IT-Gestützte Geschaftsprozesse in zukünftigen E-Mobility Szenarien
2010 VDE-Kongress 2010
Suwito D, Jäger U, Benick J, Janz S, Hermle M, Preu R, Glunz Stefan
Industtrially feasible rear side concept for n-type silicon solar cells approaching 700 mV of Voc
2010 25th EU PVSEC, Seiten: 1443 - 1445
Hopman S, Fell A, Mesec M, Kluska S, Fleischmann C, Granek F, Glunz Stefan
Influence of concentration of phosphorus dopant liquid and pulse distance on parameters of LCP selective emitters for silicon solar cells
2010 25th EU PVSEC, Seiten: 1727 - 1731
Ebong A, Renshaw J, Rounsaville B, Cooper I, Tate K, Rohatgi A, Glunz Stefan, Horteis M, Mette A, Gundemann M, Dovrat M, Kritchman E, Brusilovsky D, Benichou A
Ink jetted seed and plated grid solar cells with homogeneous high sheet resistance emitters
2010 25th EU PVSEC, Seiten: 2390 - 2394
Glunz S, Benick J, Biro D, Bivour M, Hermle M, Pysch D, Rauer M, Reichel C, Richter A, Rüdiger M, Schmiga C, Suwito D, Wolf A, Preu R
N-type silicon - enabling efficiencies \textgreater 20% in industrial production
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 50 - 56
Glunz Stefan, Benick J, Biro D, Bivour M, Hermle M, Pysch D, Rauer M, Reichel C, Richter A, Rüdiger M, Schmiga C, Suwito D, Wolf A, Preu R
N-type silicon - enabling efficiencies \textgreater 20% in industrial production
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 000050 - 000056
Bivour M, Meinhardt C, Pysch D, Reichel C, Ritzau K.-U., Hermle M, Glunz Stefan
N-type silicon solar cells with amorphous/crystalline silicon heterojunction rear emitter
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 001304 - 001308
Rüdiger M, Schmiga C, Rauer M, Hermle M, Glunz Stefan
Optimisation of industrial n-type silicon solar cells with aluminium-alloyed rear emitter by means of 2D numerical simulation
2010 25th EU PVSEC, Seiten: 2280 - 2286
Meinhardt C, Pysch D, Bivour M, Zimmermann K, Schetter C, Hermle M, Glunz Stefan
Optimization and analysis of deposition processes of amorphous silicon for silicon heterojunction solar cells
2010 25th EU PVSEC, Seiten: 1810 - 1815
Richter A, Hörteis M, Benick J, Hermle M, Glunz Stefan
Seed layer printed contact formation for highly doped boron emitters of n-type silicon solar cells with front side junction
2010 2nd Workshop on Metallization Constance, Seiten: 26 - 31
Gradmann R, Löper P, Künle M, Rothfelder M, Janz S, Hermle M, Glunz Stefan
Silicon nanocrystals in SiC: The influence of doping on crystallisation and electrical properties
2010 25th EU PVSEC, Seiten: 199 - 202
Löper P, Hiller D, Künle M, Gradmann R, Janz S, Hermle M, Zacharias M, Glunz Stefan
Silicon quantum dot superstructures for all-silicon tandem solar cells: Electrical and optical characterization
2010 22nd Workshop on Quantum Solar Energy Conversion Brigels
Rauer M, Schmiga C, Meyer K, Lossen J, Krokoszinski H.-J., Hermle M, Glunz Stefan
Simplifying the manufacturing of n-type silicon solar cells with screen-printed aluminium-alloyed rear emitter
2010 25th EU PVSEC, Seiten: 1460 - 1464
Richter A, Hoteis M, Benick J, Henneck S, Hermle M, Glunz Stefan
Towards industrially feasible high-efficiency n-type Si solar cells with boron-diffused front side emitter - combining firing stable Al2O3 passivation and fine-line printing
2010 35th IEEE Photovoltaic Specialists Conference Honolulu, Seiten: 3587 - 3592
Hiermaier, S., Riedel, W., Thoma, K.
Tragwerke unter Anprall und Explosion - Experimentelle und numerische Methoden zur Auslegung
2010 Zuverlaessigkeit und Robustheit von Tragwerken. 14. Dresdner Baustatik-Seminar 2010, Technische Universitaet Dresden, Dresden
Riedel, W., Hiermaier, S., Thoma, K.
Transient stress and failure analysis of impact experiments with ceramics
2010 3rd International Conference on Science and Technology of Advanced Ceramics, STAC 2009, Elsevier, Amsterdam, Seiten: 139 - 147
KurzfassungAt Ernst-Mach-Institut (EMI), ductile and brittle materials are studied both experimentally and numerically with the focus on shock and impact loading and associated damage effects. Experimental investigations using plate impact, edge-on impact, penetration and perforation on light gas accelerators provide input for numerical studies and allow verification of constitutive models. Hydrocodes are the standard numerical tool for the simulation of transient processes and basis of the modelling in the present paper. Besides use of commercial codes with mesh-based Lagrangean and Eulerian spatial discretization, an own meshfree SPH code has been developed at EMI. Edge-on impact experiments, plate impact tests and deep penetration in confined targets are simulated to study different loading histories and failure conditions. Significantly different material models based on continuum damage approaches as well as microstatistical modelling of inhomogeneities have been implemented. Their performances in reproducing damage fracture patterns and continued fragment loading in different ceramic types are analysed and compared to edge-on impact experiments.
Riedel, W., Hiermaier, S., Thoma, K.
Transient stress and failure analysis of impact experiments with ceramics
2010 3rd International Conference on Science and Technology of Advanced Ceramics, STAC 2009, Elsevier, Amsterdam, Seiten: 139 - 147
KurzfassungAt Ernst-Mach-Institut (EMI), ductile and brittle materials are studied both experimentally and numerically with the focus on shock and impact loading and associated damage effects. Experimental investigations using plate impact, edge-on impact, penetration and perforation on light gas accelerators provide input for numerical studies and allow verification of constitutive models. Hydrocodes are the standard numerical tool for the simulation of transient processes and basis of the modelling in the present paper. Besides use of commercial codes with mesh-based Lagrangean and Eulerian spatial discretization, an own meshfree SPH code has been developed at EMI. Edge-on impact experiments, plate impact tests and deep penetration in confined targets are simulated to study different loading histories and failure conditions. Significantly different material models based on continuum damage approaches as well as microstatistical modelling of inhomogeneities have been implemented. Their performances in reproducing damage fracture patterns and continued fragment loading in different ceramic types are analysed and compared to edge-on impact experiments.
Goldschmidt J, Fischer S, Löper P, Krämer K, Biner D, Hermle M, Glunz Stefan
Upconversion to enhance silicon solar cell efficiency - detailed experimental analysis with both coherent monochromatic irradiation and white light illumination
2010 25th EU PVSEC, Seiten: 229 - 233

2009

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Hess, S, Di Lauro, P, Oliva, A, Hanby, V
RefleC – A new Collector for Solar Cooling Applications with Operating Temperatures up to 150 °C
2009 Proceedings of the 3rd International OTTI-Conference on Solar Air-Conditioning /Palermo
Hess, S, Di Lauro,P, Oliva, A, Hanby, V
RefleC – Ein verbesserter Flachkollektor mit externen Reflektoren zur Erzeugung von Prozess-wärme bis 150 °C
2009 Proceedings of the 19. OTTI-Symposium Thermische Solarenergie / Bad Staffelstein
Hess, S, Heimsath, A
Raytracing-Untersuchungen zur Entwicklung und Optimierung von Prozesswärmekollektoren
2009 Erste Solarthermie-Technologiekonferenz / Berlin.
Reiterer, A., Hassan, T., El-Sheimy, N.
A Mobile Mapping System for the Automated Extraction of Relevant Image Data
2009 6th International Symposium on Mobile Mapping Technology, Sao Paulo, Brazil
Alemán M, Bay N, Barucha D, Knorz A, Biro D, Preu R, Glunz Stefan
Advances in electroless nickel plating for the metallization of silicon solar cells using different structuring techniques for the ARC
2009 24th EU PVSEC, Seiten: 1414 - 1418
Richter A, Benick J, Hermle M, Glunz Stefan
Amorphous silicon passivation applied to the front side boron emitter of n-type silicon solar cells
2009 24th EU PVSEC, Seiten: 1534 - 1538
Kluska S, Granek F, Rüdiger M, Hermle M, Glunz Stefan
Characterization and modeling of back-contact back-junction silicon solar cells
2009 24th EU PVSEC, Seiten: 950 - 954
Rodofili A, Hopman S, Fell A, Mayer K, Mesec M, Granek F, Glunz Stefan
Characterization of doping via laser chemical processing (LCP)
2009 24th EU PVSEC, Seiten: 1727 - 1731
Fritsch, J., Hiermaier, S., Strobl, G.
Characterizing and modeling the non-linear visco-elastoplastic tensile deformation properties of a glass fiber reinforced polypropylene
2009 DYFP 2009, the 14th International Conference on Deformation, Yield and Fracture of Polymers. Book of abstracts, Technische Universiteit Eindhoven, Eindhoven, Seiten: 187 - 190
Fritsch, J., Hiermaier, S., Strobl, G.
Characterizing and modeling the non-linear viscoelastic tensile deformation of a glass fiber reinforced polypropylene
2009 Sixteenth International Conference on Composite Materials with Regular Papers, ICCM 2007, Elsevier, Amsterdam, Seiten: 2460 - 2466
KurzfassungOn the basis of comprehensive experimental investigations on a long glass fiber reinforced polypropylene (PP-LGF) a novel rheological material model is developed. It features a decomposition of the stress into a time independent quasi-static and a time and strain dependent viscous contribution. Furthermore it allows for plastic deformations starting from the very beginning of straining and is thereby able to reproduce the absence of a purely linear elastic domain going along with the nonexistence of a defined yield point, characteristic for many fiber reinforced thermoplastic polymers. In order to approach the true quasi-static material behavior, various tensile tests were carried out. The viscous material behavior was deduced from a series of stress relaxation experiments and is described by Eyring's equation with strain dependent viscosity parameters.
Fritsch, J., Hiermaier, S., Strobl, G.
Characterizing and modeling the non-linear viscoelastic tensile deformation of a glass fiber reinforced polypropylene
2009 Sixteenth International Conference on Composite Materials with Regular Papers, ICCM 2007, Elsevier, Amsterdam, Seiten: 2460 - 2466
KurzfassungOn the basis of comprehensive experimental investigations on a long glass fiber reinforced polypropylene (PP-LGF) a novel rheological material model is developed. It features a decomposition of the stress into a time independent quasi-static and a time and strain dependent viscous contribution. Furthermore it allows for plastic deformations starting from the very beginning of straining and is thereby able to reproduce the absence of a purely linear elastic domain going along with the nonexistence of a defined yield point, characteristic for many fiber reinforced thermoplastic polymers. In order to approach the true quasi-static material behavior, various tensile tests were carried out. The viscous material behavior was deduced from a series of stress relaxation experiments and is described by Eyring's equation with strain dependent viscosity parameters.
Pysch D, Bivour M, Zimmermann K, Schetter C, Hermle M, Glunz Stefan
Comprehensive study of different PECVD-deposition methods for deposition of thin intrinsic amorphous silicon for heterojunction solar cells
2009 24th EU PVSEC, Seiten: 1580 - 1585
Goldschmidt J, Peters M, Dimroth F, Bett A, Steidl L, Zentel R, Hermle M, Glunz Stefan, Willeke G
Developing large and efficient fluorescent concentrator systems
2009 24th EU PVSEC, Seiten: 207 - 212
Hörteis M, Bartsch J, RAdtke V, Filipovic A, Glunz Stefan
Different aspects of seed layer-printed and light-induced plated front side contacts
2009 24th EU PVSEC, Seiten: 985 - 988
Filipovic A, Binder S, Hörteis M, Schmidt D, Merkel J, Glunz Stefan
Electrical properties of aerosol printed contacts
2009 24th EU PVSEC, Seiten: 1475 - 1478
Bay N, RAdtke V, Alemán M, Bartsch J, Glunz Stefan
Electrolytic nickel deposition for the front side metallization of silicon solar cells
2009 24th EU PVSEC, Seiten: 1434 - 1436
Schmich E, Kiefer F, Hörteis M, Alemán M, Glunz Stefan, Reber S
Emitter epitaxy for crystalline silicon thin film solar cells with new contact methods
2009 24th EU PVSEC, Seiten: 2570 - 2574
Horteis M, Grote D, Binder S, Filipovic A, Schmidt D, Glunz Stefan
Fine line printed and plated contacts on high ohmic emitters enabling 20% cell efficiency
2009 34th IEEE Photovoltaic Specialists Conference Philadelphia, Seiten: 000060 - 000065
Benick J, Hoex B, Dingemans G, Richter A, Hermle M, Glunz Stefan
High-efficiency n-type silicon solar cells with front side boron emitter
2009 24th EU PVSEC, Seiten: 863 - 870
Suwito D, Janz S, Hermle M, Glunz Stefan
High-efficiency silicon solar cells with intrinsic and doped A-SiCx rear side passivation
2009 24th EU PVSEC, Seiten: 2197 - 2202
Hauser H, Voisin P, Guttowski A, Mick J, Pfeifer M, Müller C, Hermle M, Glunz Stefan, Bläsi B
Honeycomb textured multicrystalline silicon via nanoimprint lithography
2009 24th EU PVSEC, Seiten: 1118 - 1122
Weidlich A, Karnouskos S, Kok K, Warmer C
Integrating smart houses with the smart grid through web services for increasing energy efficiency
2009 10th IAEE European Conference, Vienna, Austria
Schmiga C, Hörteis M, Rauer M, Meyer K, Lossen J, Krokoszinski H.-J., Hermle M, Glunz Stefan
Large-area n-type silicon solar cells with printed contacts and aluminium-alloyed rear emitter
2009 24th EU PVSEC, Seiten: 1167 - 1170
Knorz A, Aleman M, Grohe A, Preu R, Glunz Stefan
Laser ablation of antireflection coatings for plated contacts yielding solar cell efficiencies above 20 %
2009 24th EU PVSEC, Seiten: 1002 - 1005
Voisin P, Peters M, Hauser H, Helgert C, Kley E.-B., Pertsch T, Bläsi B, Hermle M, Glunz Stefan
Nanostructured back side silicon solar cells
2009 24th EU PVSEC, Seiten: 1997 - 2000
Hofmann M, Saint-Cast P, Suwito D, Seiffe J, Schmidt C, Kambor S, Gautero L, Kohn N, Nekarda J.-F., Leimenstoll A, Wagenmann D, Erath D, Catoir J, Wolke W, Janz S, Biro D, Grohe A, Rentsch J, Glunz Stefan, Preu R
Overview on crystalline silicon solar cells using PECVD rear passivation and laser-fired contacts
2009 24th EU PVSEC, Seiten: 1517 - 1522
Rauer M, Schmiga C, Hermle M, Glunz Stefan
Passivation of screen-printed aluminium-alloyed emitters for back junction n-type silicon solar cells
2009 24th EU PVSEC, Seiten: 1059 - 1062
Roth T, Rosenits P, Warta W, Glunz Stefan
Photoconductance-based excess carrier lifetime measurements on unpassivated silicon samples
2009 24th EU PVSEC, Seiten: 2004 - 2007
Goldschmidt J, Fischer S, Löper P, Peters M, Steidl L, Hermle M, Glunz Stefan
Photon management with luminescent materials
2009 21st Workshop on Quantum Solar Energy Conversion Rauris
Janz S, Voisin P, Suwito D, Peters M, Hermle M, Glunz Stefan
Photonic crystals as rear-side diffusers and reflectors for high efficiency silicon solar cells
2009 24th EU PVSEC, Seiten: 1529 - 1533
Pysch D, Ziegler J, Becker J.-P., Suwito D, Janz S, Glunz Stefan, Hermle M
Potentials and development of amorphous silicon carbide heterojunction solar cells
2009 34th IEEE Photovoltaic Specialists Conference Philadelphia, Seiten: 794 - 799
Bartsch J, RAdtke V, Savio C, Glunz Stefan
Progress in understanding the current paths and deposition mechanisms of light-induced plating and implications for the process
2009 24th EU PVSEC, Seiten: 1469 - 1474
Rosenits P, Kopp F, Roth T, Warta W, Reber S, Glunz Stefan
Quasi-steady-state photoconductance measurements on crystalline silicon thin-film material
2009 24th EU PVSEC, Seiten: 2103 - 2106
Löper P, Hartel A, Künle M, Hiller D, Janz S, Hermle M, Zacharias M, Glunz Stefan
Silicon quantum dot absorber layers for all-silicon tandem solar cells: Optical and electrical characterisation
2009 24th EU PVSEC, Seiten: 434 - 438
Löper P, Künle M, Hartel A, Goldschmidt J, Peters M, Janz S, Hermle M, Glunz Stefan, Zacharias M
Silicon quantum dot superstructures for all-silicon tandem solar cells
2009 21st Workshop on Quantum Solar Energy Conversion Rauris
Kok K, Karnouskos S, Nestle D, Dimeas A, Weidlich A, Warmer C, Strauss P, Buchholz B, Drenkard S, Hatziargyriou N
Smart houses for a smart grid
2009 20th International Conference and Exhibition on Electricity Distribution CIRED, Seiten: 1 - 4
Granek F, Reichel C, Glunz Stefan
Stability of front surface passivation of back-contact back-junction silicon solar cells under UV illumination
2009 24th EU PVSEC, Seiten: 1047 - 1050
Suwito D, Fernandez J, Janz S, Dimroth F, Glunz Stefan
The influence of annealing on the passivation quality of A-SiCX:H on crystalline silicon and germanium surfaces: H on crystalline silicon and germanium surfaces
2009 34th IEEE Photovoltaic Specialists Conference Philadelphia, Seiten: 000700 - 000704
Reiterer, A.
Traffic Sign Detection from Geo-Referenced Mobile Mapping Images
2009 GPS World Tech Talk
Warmer C, Kok K, Karnouskos S, Weidlich A, Nestle D, Selzam P, Ringelstein J, Dimeas A, Drenkard S
Web services for integration of smart houses in the smart grid
2009 Denver Grid-Interop Conference
Pysch D, Leimenstoll A, Hermle M, Glunz Stefan
Wet-chemical pre-treatment of c-Si substrates enhancing the performance of a-SiC: H/c-Si heterojunction solar cells
2009 24th EU PVSEC, Seiten: 1123 - 1127

2008

nach oben zur Jahresübersicht

Hess, S, Di Lauro, P, Rose, S, Rommel, M
Comparison of Medium Temperature Collectors for the Generation of Process Heat
2008 proceedings of EuroSun 2008. Solar Collector Technology / Lisbon.
Hess, S, Di Lauro, P, Rose, S, Rommel, M
Raytracing-Untersuchungen für die Entwicklung von Prozesswärmekollektoren
2008 Proceedings of the 18. OTTI-Symposium Thermische Solarenergie / Bad Staffelstein
Goldschmidt J, Loper P, Fischer S, Janz S, Peters M, Glunz Stefan, Willeke G, Lifshitz E, Kramer K, Biner D
Advanced upconverter systems with spectral and geometric concentration for high upconversion efficiencies
2008 2008 Conference on Optoelectronic and Microelectronic Materials and Devices, Seiten: 307 - 311
Peters C, Engelhart P, Hlusiak M, Wade R, Jesswein R, Rychtarik D, Müller J, Ulzhöfer C, Spätlich S, Neubert T, Schmiga C, Kray D, Grohe A, Glunz Stefan
Alba-development of high-effciency multi-crystalline si ewt solar cells for industrial fabrication at q-cells
2008 23rd EU PVSEC, Seiten: 1010 - 1013
Janz S, Ziegler J, Pysch D, Suwito D, Glunz Stefan
Amorphous silicon carbide hetero-emitters for high efficiency silicon solar cells
2008 23rd EU PVSEC, Seiten: 1720 - 1723
Weidlich A, Veit D
Analyzing interrelated markets in the electricity sector -- The case of wholesale power trading in Germany
2008 IEEE Power and Energy Society General Meeting, Pittsburgh, Seiten: 1 - 8
Ryan, S., Schaefer, F., Guyot, M., Hiermaier, S., Lambert, M.
Characterizing the transient response of CFRP/Al HC spacecraft structures induced by space debris impact at hypervelocity
2008 Hypervelocity impact. Proceedings of the 2007 symposium, Elsevier, Amsterdam, Seiten: 1756 - 1763
KurzfassungTo quantify the disturbance induced by the impact of micrometeoroid and space debris particles at hypervelocity on vibration-sensitive CFRP/Al HC SP satellite platforms a method is presented which uses experimentally validated hydrocode models to characterize the impact-induced transient wave in the local structure. Key features of the transient waveform are simplified by a mathematical function which is expressed in terms of impactor momentum. Evolution of the transient waveform is characterized using multiple measurement gauges located on the sandwich panel facesheets outside the area of mechanical damage. The characterization is then used to extrapolate the elastic waveform back to the impact location. The elastic-equivalent excitation of a CFRP/Al HC SP is defined in terms of force with respect to time for application in finite element: structural codes for propagation of the local disturbance to vibration-sensitive locations (i.e. measurement devices).
Ryan, S., Schaefer, F., Guyot, M., Hiermaier, S., Lambert, M.
Characterizing the transient response of CFRP/Al HC spacecraft structures induced by space debris impact at hypervelocity
2008 Hypervelocity impact. Proceedings of the 2007 symposium, Elsevier, Amsterdam, Seiten: 1756 - 1763
KurzfassungTo quantify the disturbance induced by the impact of micrometeoroid and space debris particles at hypervelocity on vibration-sensitive CFRP/Al HC SP satellite platforms a method is presented which uses experimentally validated hydrocode models to characterize the impact-induced transient wave in the local structure. Key features of the transient waveform are simplified by a mathematical function which is expressed in terms of impactor momentum. Evolution of the transient waveform is characterized using multiple measurement gauges located on the sandwich panel facesheets outside the area of mechanical damage. The characterization is then used to extrapolate the elastic waveform back to the impact location. The elastic-equivalent excitation of a CFRP/Al HC SP is defined in terms of force with respect to time for application in finite element: structural codes for propagation of the local disturbance to vibration-sensitive locations (i.e. measurement devices).
Reichel C, Granek F, Benick J, Schultz-Wittmann O, Glunz Stefan
Comparison of emitter saturation current densities determined by quasi-steady-state photoconductance measurements of effective carrier lifetimes at high and low injections
2008 23rd EU PVSEC, Seiten: 1664 - 1669
Roth T, Rosenits P, Rüdiger M, Warta W, Glunz Stefan
Comparison of photoconductance- and photo-luminescence-based lifetime measurement techniques
2008 2008 Conference on Optoelectronic and Microelectronic Materials and Devices, Seiten: 249 - 252
Reiterer, A., Lehmann, M., Miljanovic, M., Ali, H., Paar, G., Egly, U., Eiter, T., Kahmen, H.
Deformation Monitoring Using a New Kind of Optical 3D Measurement: Components and Perspectives
2008 13th FIG International Symposium on Deformation Measurements and Analysis / 4th IAG Symposium on Geodesy for Geotechnical and Structural Engineering, Lissabon
Suwito D, Roth T, Pysch D, Korte L, Richter A, Janz S, Glunz Stefan
Detailed study on the passivation mechanism of a-SixC1-x for the solar cell rear side
2008 23rd EU PVSEC, Seiten: 1023 - 1028
Woehl R, Hörteis M, Glunz Stefan
Determination of the effective optical width of screen-printed and aerosol-printed and plated fingers
2008 23rd EU PVSEC, Seiten: 1377 - 1382
Goldschmidt J, Peters M, Dimroth F, Glunz Stefan, Willeke G
Efficiency enhancement of fluorescent concentrators with photonic structures and material combinations
2008 23rd EU PVSEC, Seiten: 193 - 197
Reiterer, A., Lehmann, M., Miljanovic, M., Ali, H., Paar, G., Egly, U., Eiter, T., Kahmen, H.
Ein lernendes 3D Deformations-Messsystem
2008 Pangeo Austria, Wien
Rublack T, Alemán M, Glunz Stefan
Evaluation of the laser melting process of different materials for the front-side metallisation of silicon solar cells
2008 23rd EU PVSEC, Seiten: 1419 - 1421
Granek F, Hermle M, Reichel C, Schultz-Wittmann O, Glunz Stefan
High- efficiency back-contact back-junction silicon solar cell research at Fraunhofer ISE
2008 23rd EU PVSEC, Seiten: 991 - 995
Hiermaier, S.
Hydrocodes - Simulation tool of choice for transient processes
2008 3. Workshop "Bau-Protect" Buildings and Utilities Protection, Universit�t der Bundeswehr Muenchen, Institut fuer Mechanik und Statik, Neubiberg, Seiten: 21 - 22
Hörteis M, Richter P, Glunz Stefan
Improved front side metallization by aerosol jet printing of hotmelt INKS
2008 23rd EU PVSEC, Seiten: 1402 - 1405
Roth T, Hohl-Ebinger J, Schmich E, Warta W, Glunz Stefan, Sinton R
Improving the accuracy of Suns-VOC measurements using spectral mismatch correction
2008 33rd IEEE Photovoltaic Specialists Conference San Diego, Seiten: 1 - 5
Alemán M, Bay N, Gautero J, Specht J, Stüwe D, Neubauer R, Baurcha D, Biro D, Rentsch J, Glunz Stefan, Preu R
Industrially feasible front-side metallization based on ink-jet masking and nickel plating
2008 23rd EU PVSEC, Seiten: 1953 - 1956
Eichhorn, A., Fabiankowitsch, J., Haberler-Weber, M., Reiterer, A.
Investigation of Dynamic Thermal Effects with Non-Parametric and 'Parametric' Deformation Models
2008 13th FIG International Symposium on Deformation Measurements and Analysis / 4th IAG Symposium on Geodesy for Geotechnical and Structural Engineering, Lissabon
Kray D, Aleman M, Fell A, Hopman S, Mayer K, Mesec M, Muller R, Willeke G, Glunz Stefan, Bitnar B, Neuhaus D.-H., Ludemann R, Schlenker T, Manz D, Bentzen A, Sauar E, Pauchard A, Richerzhagen B
Laser-doped silicon solar cells by laser chemical processing (LCP) exceeding 20% efficiency
2008 33rd IEEE Photovoltaic Specialists Conference San Diego, Seiten: 1 - 3
Rudolph D, Alemán M, Bay N, Mayer K, Glunz Stefan
Laser-induced nickel deposition from an aqueous electrolyte for the front-side metallization of silicon solar cells
2008 23rd EU PVSEC, Seiten: 1427 - 1430
Rosenits P, Roth T, Reber S, Warta W, Glunz Stefan
Lifetime studies on crystalline silicon thin-films by photoluminescence measurements
2008 23rd EU PVSEC, Seiten: 2224 - 2227
Rodofili A, Fell A, Hopman S, Mayer K, Willeke G, Kray D, Glunz Stefan
Local p-type back surface fields via laser chemical processing (LCP): First experiments
2008 23rd EU PVSEC, Seiten: 1808 - 1811
Kluska S, Granek F, Hermle M, Glunz Stefan
Loss analysis of high-efficiency back-contact back-junction silicon solar cells
2008 23rd EU PVSEC, Seiten: 1590 - 1595
Fischer S, Goldschmidt J, Löper P, Janz S, Peters M, Glunz Stefan, Kigel A, Lifshitz E, Krämer K
Material characterization for advanced upconverter systems
2008 23rd EU PVSEC, Seiten: 620 - 623
Mayer K, Kray D, Pérez T, Schuhmann M, Glunz Stefan
New surfactants for combined cleaning and texturing of mono-crystalline silicon wafers after wire-sawing
2008 23rd EU PVSEC, Seiten: 1109 - 1113
Hiermaier, S., Gebbeken, N.
Numerical methods for dynamic processes
2008 3. Workshop "Bau-Protect" Buildings and Utilities Protection, Universit�t der Bundeswehr Muenchen, Institut fuer Mechanik und Statik, Neubiberg, Seiten: 17 - 18
Benick J, Schultz-Wittmann O, Schön J, Glunz Stefan
Passivation of boron emitters by local overcompensation with phosphorus
2008 23rd EU PVSEC, Seiten: 1550 - 1552
Mingirulli N, Trittler S, Bui M, Grohe A, Biro D, Preu R, Glunz Stefan
Passivation of laser-drilled via holes for emitter-wrap-through-cells
2008 23rd EU PVSEC, Seiten: 996 - 999
Peters M, Goldschmidt J, Löper P, Ulbrich C, Kirchartz T, Fahr S, Bläsi B, Glunz Stefan, Gombert A
Photonic structures for the application on solar cells
2008 20th Workshop on Quantum Solar Energy Conversion
Borden P, Xu L, McDougall B, Chang C, Pysch D, Voisin P, Glunz Stefan
Polysilicon tunnel junctions as alternates to diffused junctions
2008 23rd EU PVSEC, Seiten: 1149 - 1152
Granek F, Hermle M, Reichel C, Grohe A, Schultz-Wittmann O, Glunz Stefan
Positive effects of front surface field in high-efficiency back-contact back-junction n-type silicon solar cells
2008 33rd IEEE Photovoltaic Specialists Conference San Diego, Seiten: 1 - 5
Weidlich A, Veit D
PowerACE: Ein agentenbasiertes Tool zur Simulation von Strom- und Emissionsmärkten
2008 IT in der Energiewirtschaft: Track Proceedings der MKWI 2008, Seite: 15
Suwito D, Janz S, Schetter C, Glunz Stefan, Roth K
Process transfer of a-SixC1-x passivation layers from a laboratorytype to an industrial in-line PECVD reactor
2008 33rd IEEE Photovoltaic Specialists Conference San Diego, Seiten: 1 - 4
Glunz Stefan, Aleman M, Bartsch J, Bay N, Bayer K, Bergander R, Filipovic A, Greil S, Grohe A, Horteis M, Knorz A, Menko M, Mette A, Pysch D, RAdtke V, Richter P, Rudolph D, Rublack T, Schetter C, Schmidt D, Schultz O, Woehl R
Progress in advanced metallization technology at Fraunhofer ISE
2008 33rd IEEE Photovoltaic Specialists Conference San Diego, Seiten: 1 - 4
Goldschmidt J, Peters M, Löper P, Schultz O, Dimroth F, Bett A, Gombert A, Glunz Stefan, Willeke G
Progress in photon management for full spectrum utilization with luminescent materials
2008 20th Workshop on Quantum Solar Energy Conversion
Kasemann M, Kwapil W, Walter B, Giesecke J, Michl B, The M, Wagner J.-M., Bauer J, Schütt A, Carstensen J, Kampwerth H, Gundel P, Schubert M, Bardos R, Föll H, Nagel H, Würfel P, Trupke T, Breitenstein O, Warta W, Glunz Stefan
Progress in silicon solar cell characterization with infrared imaging methods
2008 23rd EU PVSEC, Seiten: 965 - 973
Hermle M, Granek F, Schultz-Wittmann O, Glunz Stefan
Shading effects in back-junction back-contacted silicon solar cells
2008 33rd IEEE Photovoltaic Specialists Conference San Diego, Seiten: 1 - 4
Fell A, Kray D, Wütherich T, Müller R, Willeke G, Glunz Stefan
Simulation of phase changes and dopant diffusion in silicon for the manufacturing of selective phosphorous emitters via laser chemical processing
2008 23rd EU PVSEC, Seiten: 272 - 274
Kasemann M, Kwapil W, Schubert M, Habenicht H, Walter B, The M, Kontermann S, Rein S, Breitenstein O, Bauer J, Lotnyk A, Michl B, Nagel H, Schutt A, Carstensen J, Foll H, Trupke T, Augarten Y, Kampwerth H, Bardos R, Pingel S, Berghold J, Warta W, Glunz Stefan
Spatially resolved silicon solar cell characterization using infrared imaging methods
2008 33rd IEEE Photovoltaic Specialists Conference San Diego, Seiten: 1 - 7
Richter A, Benick J, Glunz Stefan
Spectral ellipsometry analysis of ultrathin amorphous silicon layers
2008 23rd EU PVSEC, Seiten: 1724 - 1727
Vergniaud, J.B., Guyot, M., Lambert, M., Schaefer, F., Ryan, S., Hiermaier, S., Taylor, E.
Structural vibrations induced by HVI - Application to the Gaia spacecraft
2008 Hypervelocity impact. Proceedings of the 2007 symposium, Elsevier, Amsterdam, Seiten: 1836 - 1843
KurzfassungGiven the growing stability needed for spacecraft in operation to ensure functioning of future instruments whose sensitivity requires an important technological step, perturbations encounter in orbital conditions that used to be negligible, become today an issue. This is the case of micrometeorite impacts whose energy could induce modal response of the flexible structure and imply a dynamic response of the spacecraft which could probably be disturbing for the instrument functioning. The impact environment that could be encountered by the spacecraft is preliminary studied before the definition of test to recreate the excitation with light-gas gun. Experiments are made on samples of structure representative of the ongoing Gaia astrometric mission project. Response of the structure is recorded to be correlated to finite elements model of the sample. The excitation is then extrapolated to orbital conditions and to Gaia finite elements model. The final perturbation is compared to the specification. The main conclusion is that for daily impact event, dynamic response of the structure will not disturb Gaia functioning. Nevertheless, for a yearly impact event, the astrometric mission will largely be disturbed by the dynamic response of the structure to the impact.
Vergniaud, J.B., Guyot, M., Lambert, M., Schaefer, F., Ryan, S., Hiermaier, S., Taylor, E.
Structural vibrations induced by HVI - Application to the Gaia spacecraft
2008 Hypervelocity impact. Proceedings of the 2007 symposium, Elsevier, Amsterdam, Seiten: 1836 - 1843
KurzfassungGiven the growing stability needed for spacecraft in operation to ensure functioning of future instruments whose sensitivity requires an important technological step, perturbations encounter in orbital conditions that used to be negligible, become today an issue. This is the case of micrometeorite impacts whose energy could induce modal response of the flexible structure and imply a dynamic response of the spacecraft which could probably be disturbing for the instrument functioning. The impact environment that could be encountered by the spacecraft is preliminary studied before the definition of test to recreate the excitation with light-gas gun. Experiments are made on samples of structure representative of the ongoing Gaia astrometric mission project. Response of the structure is recorded to be correlated to finite elements model of the sample. The excitation is then extrapolated to orbital conditions and to Gaia finite elements model. The final perturbation is compared to the specification. The main conclusion is that for daily impact event, dynamic response of the structure will not disturb Gaia functioning. Nevertheless, for a yearly impact event, the astrometric mission will largely be disturbed by the dynamic response of the structure to the impact.
Benick J, Hoex B, Schultz O, Glunz Stefan
Surface passivation of boron diffused emitters for high efficiency solar cells
2008 33rd IEEE Photovoltaic Specialists Conference San Diego, Seiten: 1 - 5
Rüdiger M, Roth T, Warta W, Glunz Stefan
Temperature-dependent quasi-steady-state photoluminescence lifetime measurements for defect spectroscopy
2008 23rd EU PVSEC, Seiten: 1333 - 1337
Roth T, Rüdiger M, Trupke T, Glunz Stefan
Titanium-related defect levels in silicon analyzed by temperature-dependent photoluminescence lifetime spectroscopy
2008 33rd IEEE Photovoltaic Specialists Conference San Diego, Seiten: 1 - 4
Schmiga C, Hermle M, Glunz Stefan
Towards 20% efficient n-type silicon solar cells with screen-printed aluminium-alloyed rear emitter
2008 23rd EU PVSEC
RAdtke V, Bartsch J, Greil S, Schetter C, Bergander R, Glunz Stefan
Understanding the electrochemical mechanisms of light induced plating by means of voltammetric techniques
2008 23rd EU PVSEC, Seiten: 1785 - 1788
Löper P, Goldschmidt J, Fischer S, Peters M, Meijerink A, Biner D, Krämer K, Schultz-Wittmann O, Glunz Stefan, Luther J
Upconversion for silicon solar cells: Material and system characterisation
2008 23rd EU PVSEC, Seiten: 173 - 180

2007

nach oben zur Jahresübersicht

Hess, S
Application of Medium Temperature Collectors for Solar Air-Conditioning
2007 Proceedings of the 2nd International Conference on Solar Air-Conditioning /Tarragona.
Goldschmidt J, Peters M, Löper P, Schultz O, Dimroth F, Glunz Stefan, Gombert A, Willeke G
Advanced fluorescent concentrator system design
2007 22nd EU PVSEC, Seiten: 608 - 612
Glunz Stefan, Nekarda J, Mäckel H, Cuevas A
Analyzing back contacts of silicon solar cells by suns-voc-measurements at high illumination densities
2007 22nd EU PVSEC, Seiten: 849 - 853
Alemán M, Bay N, Fabritius M, Glunz Stefan
Characterization of electroless nickel plating on silicon solar cells for the front side metallization
2007 22nd EU PVSEC, Seiten: 1590 - 1592
Hofmann M, Schmidt C, Kohn N, Grambole D, Rentsch J, Glunz Stefan, Preu R
Detailed analysis of amorphous silicon passivation layers deposited in industrial in-line and laboratory-type pecvd reactors
2007 22nd EU PVSEC, Seiten: 1528 - 1531
Pysch D, Mette A, Filipovic A, Glunz Stefan
Detailed analysis of fine line printed and plated solar cell contacts
2007 22nd EU PVSEC, Seiten: 1238 - 1243
Rosenits P, Roth T, Diez S, Macdonald D, Glunz Stefan
Detailed studies of manganese in silicon using lifetime spectroscopy and deep-level transient spectroscopy
2007 22nd EU PVSEC, Seiten: 1480 - 1483
Würfel P, Trupke T, Rüdiger M, Puzzer T, Schäffer E, Warta W, Glunz Stefan
Diffusion lengths of silicon solar cells from luminescence images
2007 22nd EU PVSEC, Seiten: 390 - 393
Löper P, Goldschmidt J, Peters M, Biner D, Krämer K, Schultz O, Glunz Stefan, Luther J
Efficient upconversion systems for silicon solar cells
2007 22nd EU PVSEC, Seiten: 589 - 594
Huberth, F., Hiermaier, S.
Experimental parameter identification for material models including deformation induced volume dilation for thermoplastic materials
2007 Experimental Analysis of Nano and Engineering Materials and Structures. Proceedings of the 13th International Conference on Experimental Mechanics 2007, Springer Netherland, Dordrecht, Seiten: 293 - 294
KurzfassungSimulation of structures made from thermoplastic materials under crash loads including large deformations and failure is still a challenge for most existing numerical tools. To model the complex mechanical behaviour of thermoplastic materials new models have been developed. To reproduce the mechanical behaviour in the simulation, model parameters for each material have to be identified by experimental testing.
Hofmann M, Kambor S, Schmidt C, Grambole D, Rentsch J, Glunz Stefan, Preu R
Firing stable surface passivation using all-PECVD stacks of SiOx: H and SiNx:H
2007 22nd EU PVSEC, Seiten: 1030 - 1033
Granek F, Reichel C, Hermle M, Huljic D, Schultz O, Glunz Stefan
Front surface passivation of n-type high-efficiency back-junction silicon solar cells using front surface field
2007 22nd EU PVSEC, Seiten: 1454 - 1457
Hörteis M, Mette A, Richter P, Fidorra F, Glunz Stefan
Further progress in metal aerosol jet printing for front side metallization of silicon solar cells
2007 22nd EU PVSEC, Seiten: 1039 - 1042
Rüdiger M, Trupke T, Würfel P, Roth T, Glunz Stefan
Influence of photon reabsorption on temperature dependent quasi-steady-state photoluminescence lifetime measurements on crystalline silicon
2007 22nd EU PVSEC, Band: 92
Grohe A, Wütherich T, Knorz A, Nekarda J, Mingirulli N, Harmel C, Preu R, Glunz Stefan
Laser processes for the industrial production of high efficiency silicon solar cells
2007 22nd EU PVSEC, Seiten: 1751 - 1754
Jimeno J, Bueno G, Lago R, Freire I, Pérez L, Recart F, Hoces I, Azkona N, Alonso J, Sánchez-Friera P, Glunz Stefan, Emanuel G, Ruiz R, Pohl A, Wolke W, Schubert M
Low cost using ultra-thin bifacial cells
2007 22nd EU PVSEC, Seiten: 875 - 878
Janz S, Suwito D, Glunz Stefan
Passivation mechanisms of amorphous SixC1-x layers on highly doped and textured Si surfaces
2007 22nd EU PVSEC, Seiten: 1454 - 1457
Roth T, Rüdiger M, Rosenits P, Diez S, Trupke T, Bardos R, Glunz Stefan
Photoluminescence lifetime spectroscopy surface recombination analysis
2007 22nd EU PVSEC, Seiten: 1002 - 1005
Goldschmidt J, Peters M, Löper P, Glunz Stefan, Gombert A, Willeke G
Photon management for full spectrum utilization with fluorescent materials
2007 19th Workshop on Quantum Solar Energy Conversion
Kray D, Fell A, Hopman S, Mayer K, Mesec M, Glunz Stefan, Willeke G
Progress in laser chemical processing (LCP) for innovative solar cell microstructuring and wafering applications
2007 22nd EU PVSEC, Seiten: 1227 - 1230
Trupke T, Bardos R, Abbott M, Würfel P, Pink E, Augarten Y, Chen F, Fisher K, Cotter J, Kasemann M, Rüdiger M, Kontermann S, Schubert M, The M, Glunz Stefan, Warta W, Macdonald D, Tan J, Cuevas A, Bauer J, Gupta R, Breitenstein O, Buonassisi T, Tarnowski G, Lorenz A, Hartmann H, Neuhaus D, Fernandez J
Progress with luminescence imaging for the characterisation of silicon wafers and solar cells
2007 22nd EU PVSEC, Seiten: 22 - 31
Schultz O, Mette A, Preu R, Glunz Stefan
Silicon solar cells with screen-printed front side metallization exceeding 19% efficiency
2007 22nd EU PVSEC, Seiten: 980 - 983
Allardyce G, Cahalen J, Rasch J, Ridler T, Weigel O, Frőhlich H, Kappler H, Oberholtzer F, Rattey C, Mette A, Schetter C, Glunz Stefan
The commercial application of light induced electroplating for improving the efficiency of crystalline silicon solar cells
2007 22nd EU PVSEC, Seiten: 1578 - 1580
Hiermaier, S., Wicklein, M.
Zellulare Werkstoffe in der Crashsimulation : Charakterisierung und numerische Simulation
2007 Polyurethan 2007. Automotive - Bauen - Daemmen - Komfort - Struktur, VDI Verlag, Duesseldorf

2006

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