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Deep-Level Defects in High-Dose Proton Implanted and High-Temperature Annealed Silicon

ECS Transactions 2014年第11期64卷

作者： Moriz Jelinek Johannes Laven Mathias Rommel Werner Schustereder Hans-Joachim Schulze Lothar Frey Reinhart Job Infineon Technologies Austria AG Infineon Technologies AG Fraunhofer Institute for Integrated Systems and Device Technology Department of Electrical Engineering and Computer Science Muenster University of Applied Sciences

We review the principal mechanisms of deep-level defect formation after proton irradiation and subsequent annealing of float zone grown crystalline silicon. Various reaction paths commonly related to vacancy-complexes, interstitial oxygen and hydrogen are discussed. In the experimental part DLTS results of proton-irradiated pn-diode structures are presented. It appears that some detected defects show a thermal stability differing from that reported in literature. Furthermore the metastability of two defects at 300 meV and 418 meV below the conduction band is examined. This behavior commonly designated to a negative-U defect is for the first time reported in a sample annealed at 350° C.

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Efficient hole extraction for metal oxide based silicon heterojunction solar cells: A simulation study

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AIP Conference Proceedings 2018年第1期1999卷

作者： Christoph Messmer Martin Bivour Jonas Schön Martin Hermle 1Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstraße 2 79110 Freiburg Germany 2Department of Sustainable Systems Engineering (INATECH) Albert-Ludwigs-University 79110 Freiburg Germany

To assist the engineering of novel silicon heterojunctions, numerical device simulations (Sentaurus TCAD) are used to improve knowledge regarding relevant heterojunction and thin film properties. This knowledge is necessary to understand limitations of current contacts and allow systematical optimization. With the focus on metal oxide based hole contacts, it is shown that for an ideal hole extraction from the c-Si absorber via the a-Si buffer and the transition metal oxide (TMO) into the external metal electrode, two conditions have to be fulfilled: A.) An induced c-Si pn-junction with a high p/n ratio is needed which is provided by a high metal oxide work function. B.) At the TMO/a-Si interface an efficient hole extraction into the n-type TMO must be guaranteed by band-to-band or trap-assisted tunneling. If A or/and B are not fulfilled the standard pn-junction theory is violated which results in power losses caused by insufficient hole selectivity.

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Carrier-envelope offset stable, coherently combined ytterbium-doped fiber CPA delivering 1 kW of average power

arXiv

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arXiv 2022年

作者： Shestaev, E. Hädrich, S. Walther, N. Eidam, T. Klenke, Arno Seres, I. Bengery, Z. Jójárt, P. Várallyay, Z. Börzsönyi, Á. Limpert, J. Active Fiber Systems GmbH Ernst-Ruska-Ring 17 Jena07745 Germany Friedrich-Schiller-Universität Jena Abbe Center of Photonics Institute of Applied Physics Albert-Einstein-Straße 15 Jena07745 Germany Helmholtz-Institute Jena Fröbelstieg 3 Jena07743 Germany ELI-ALPS ELI-HU Non-Profit Ltd. Wolfgang Sandner utca 3. SzegedH-6728 Hungary Fraunhofer Institute for Applied Optics and Precision Engineering IOF Albert-Einstein-Straße 7 Jena07745 Germany

We present a carrier-envelope offset (CEO) stable ytterbium-doped fiber chirped-pulse amplification system employing the technology of coherent beam combining and delivering more than 1 kW of average power at a pulse repetition rate of 80 MHz. The CEO stability of the system is 220 mrad rms, characterized out-of-loop with an f-to-2f interferometer in a frequency offset range of 10 Hz to 20 MHz. The high power amplification system boosts the average power of the CEO stable oscillator by five orders of magnitude, while increasing the phase noise by only 100 mrad. No evidence of the CEO noise deterioration due to coherent beam combining has been found. Low-frequency CEO fluctuations at the CPA are suppressed by a "slow loop" feedback. This is the first demonstration of a coherently combined laser system delivering an outstanding average power and a high CEO stability at the same time. Copyright © 2022, The Authors. All rights reserved.

关键词： Pulse repetition rate

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Technical debt and agile software development practices and processes: An industry practitioner survey

arXiv

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arXiv 2021年

作者： Holvitie, Johannes Licorish, Sherlock A. Spínola, Rodrigo O. Hyrynsalmi, Sami MacDonell, Stephen G. Mendes, Thiago S. Buchan, Jim Leppänen, Ville Turku Centre for Computer Science Software Development Laboratory Turku Finland University of Turku Department of Information Technology Turku Finland University of Otago Department of Information Science Otago Dunedin New Zealand Salvador University Graduate Program in Systems and Computer Bahia Salvador Brazil Federal University of Bahia Fraunhofer Project Center for Software and System Engineering Salvador Brazil Tampere University of Technology Pori Campus Pori Finland Federal Institute of Bahia Information Technology Department Bahia Santo Amaro Brazil Auckland University of Technology School of Engineering Computer and Mathematical Sciences Auckland New Zealand

Context: Contemporary software development is typically conducted in dynamic, resource-scarce environments that are prone to the accumulation of technical debt. While this general phenomenon is acknowledged, what remains unknown is how technical debt specifically manifests in and affects software processes, and how the software development techniques employed accommodate or mitigate the presence of this debt. Objectives: We sought to draw on practitioner insights and experiences in order to classify the effects of agile method use on technical debt management, given the popularity and perceived success of agile methods. We explore the breadth of practitioners' knowledge about technical debt;how technical debt is manifested across the software process;and the perceived effects of common agile software development practices and processes on technical debt. In doing so, we address a research gap in technical debt knowledge and provide novel and actionable managerial recommendations. Method: We designed, tested and executed a multi-national survey questionnaire to address our objectives, receiving 184 responses from practitioners in Brazil, Finland, and New Zealand. Results: Our findings indicate that: 1) Practitioners are aware of technical debt, although, there was under utilization of the concept, 2) Technical debt commonly resides in legacy systems, however, concrete instances of technical debt are hard to conceptualize which makes it problematic to manage, 3) Queried agile practices and processes help to reduce technical debt;in particular, techniques that verify and maintain the structure and clarity of implemented artifacts (e.g., Coding standards and Refactoring) positively affect technical debt management. Conclusions: The fact that technical debt instances tend to have characteristics in common means that a systematic approach to its management is feasible. However, notwithstanding the positive effects of some agile practices on technical debt management, comp

关键词： Legacy systems

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Erratum to “A Simple Phenomenological Model for Magnetic Shape Memory Actuators” [Jan 15 Art. ID 4002608]

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IEEE Transactions on Magnetics 2015年第12期51卷

作者： Johannes Ziske Fabian Ehle Holger Neubert Aaron D. Price Jens Lienig Institute of Electromechanical and Electronic Design Dresden University of Technology Dresden Germany Fraunhofer Institute for Ceramic Technologies and Systems IKTS Dresden Germany Department of Mechanical and Materials Engineering University of Western Ontario London ON Canada

Equations (9) and (10) [1, p. 3] of the above-named work are corrected.

关键词： Actuators Magnetic hysteresis Magnetic flux Shape memory alloys

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Hybridized Exciton-Photon-Phonon States in a Transition Metal Dichalcogenide van der Waals Heterostructure Microcavity

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Physical Review Letters 2022年第8期128卷 087401-087401页

作者： Donghai Li Hangyong Shan Christoph Rupprecht Heiko Knopf Kenji Watanabe Takashi Taniguchi Ying Qin Sefaattin Tongay Matthias Nuß Sven Schröder Falk Eilenberger Sven Höfling Christian Schneider Tobias Brixner Institut für Physikalische und Theoretische Chemie Universität Würzburg Am Hubland 97074 Würzburg Germany University of Science and Technology of China 230026 Hefei China Institute of Physics University of Oldenburg D-26129 Oldenburg Germany Technische Physik and Wilhelm Conrad Röntgen Research Center for Complex Material Systems Universität Würzburg Am Hubland 97074 Würzburg Germany Institute of Applied Physics Abbe Center of Photonics Friedrich Schiller University Albert-Einstein-Straße 15 07745 Jena Germany Fraunhofer-Institute for Applied Optics and Precision Engineering IOF Albert-Einstein-Straße 7 07745 Jena Germany Max Planck School of Photonics Albert-Einstein-Straße 7 07745 Jena Germany Research Center for Functional Materials National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan International Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba Ibaraki 305-0044 Japan Materials Science and Engineering School of Engineering of Matter Transport and Energy Arizona State University Tempe Arizona 85287 USA Center for Nanosystems Chemistry (CNC) Universität Würzburg Theodor-Boveri-Weg 97074 Würzburg Germany

Excitons in atomically thin transition-metal dichalcogenides (TMDs) have been established as an attractive platform to explore polaritonic physics, owing to their enormous binding energies and giant oscillator strength. Basic spectral features of exciton polaritons in TMD microcavities, thus far, were conventionally explained via two-coupled-oscillator models. This ignores, however, the impact of phonons on the polariton energy structure. Here we establish and quantify the threefold coupling between excitons, cavity photons, and phonons. For this purpose, we employ energy-momentum-resolved photoluminescence and spatially resolved coherent two-dimensional spectroscopy to investigate the spectral properties of a high-quality-factor microcavity with an embedded WSe2 van der Waals heterostructure at room temperature. Our approach reveals a rich multibranch structure which thus far has not been captured in previous experiments. Simulation of the data reveals hybridized exciton-photon-phonon states, providing new physical insight into the exciton polariton system based on layered TMDs.

关键词： Exciton polariton Phonon polariton Transition metal dichalcogenides Confocal imaging Femtosecond laser spectroscopy Fluorescence spectroscopy Four-wave mixing

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CHARACTERISATION OF URBAN AIR QUALITY INDOOR/OUTDOOR PARTICULATE MATTER CHEMICAL CHARACTERISTICS AND SOURCE-TO-INHALED DOSE RELATIONSHIPS (URBAN-AEROSOL)

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Journal of Aerosol Science 2001年 32卷 1075-1076页

作者： M. LAZARIDIS D.N. ASIMAKOPOULOS M. BRANIS I. COLBECK I. DROSSINOS C. DYE K. ELEFTHERIADIS H. FLOCAS C. HELMIS W. HOLLANDER Housiadas J. Hovorka N. KALOGERAKIS J. SMOLIK F. STORDAL T. SVENDBY V. ZDIMAL Norwegian Institute for Air Research (NILU) PO BOX 100 N 2007 Kjeller Norway Technical University of Crete Department of Environmental Engineering 73100 Chania Greece University of Athens Department of Physics Greece Charles University Faculty of Science Prague Czech Republic Department of Biological Sciences University of Essex U. K. Institute for Systems Informatics and Safety (ISIS) JRC-Ispra Italy N.C.S.R. Demokritos 15310 Ag. Paraskeui Attiki Greece Fraunhofer-Institut fur Toxikologie und Aerosolforschung (FhG/ITA) Hannover Germany Institute of Chemical Process Fundamentals ASCR Prague Czech Republic

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Strain and screening: Optical properties of a small-diameter carbon nanotube from first principles

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Physical Review B 2019年第7期99卷 075140-075140页

作者： Christian Wagner Jörg Schuster André Schleife Technische Universität Chemnitz Center for Microtechnologies Reichenhainer Straße 70 09126 Chemnitz Germany Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA Fraunhofer Institute for Electronic Nano Systems (ENAS) Technologiecampus 3 09126 Chemnitz Germany Dresden Center for Computational Materials Science (DCMS) Technische Universität Dresden 01062 Dresden Germany Frederick Seitz Materials Research Laboratory University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA National Center for Supercomputing Applications University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA

Carbon nanotubes (CNTs) are a one-dimensional material system with intriguing physical properties that lead to emerging applications. While CNTs are unusually strain resistant compared to bulk materials, their optical-absorption spectrum is highly strain dependent. It is an open question, as to what extent this is attributed to strain-dependent (i) electronic single-particle transitions, (ii) dielectric screening, or (iii) atomic geometries including CNT radii. We use cutting-edge theoretical spectroscopy to explain strain-dependent electronic structure and optical properties of an (8,0) CNT. Quasiparticle effects are taken into account using Hedin's GW approximation and excitonic effects are described by solving a Bethe-Salpeter-equation for the optical polarization function. This accurate first-principles approach allows us to identify an influence of strain on screening of the Coulomb electron-electron interaction and to quantify the impact on electronic structure and optical absorption of one-dimensional systems. We interpret our thoroughly converged results using an existing scaling relation and extend the use of this relation to strained CNTs. We show that it captures optical absorption with satisfactory accuracy, as long as screening, quasiparticle gap, and effective electron and hole masses of the strained CNT are known.

关键词： Band gap Molecular spectra Strain Nanotubes GW method Many-body techniques

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TABSOLAR^Ⓡ – a novel approach of thermo-active (solar) building systems based on ultra-high performance concrete (UHPC)

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Solar Energy Advances 2022年 2卷

作者： Hermann, Michael Hildebrandt, Christina Mattmüller, Jan Felic, Artur Sablotny, Tino Tesari, Iwiza Bethge, Klaus Böke, Jens Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstr. 2 Freiburg 79110 Germany CAS Software AG CAS-Weg 1–5 Karlsruhe 76131 Germany G.tecz Engineering GmbH Eichwaldstr. 38 Kassel 34123 Germany Karlsruhe Institute of Technology KIT Hermann-von-Helmholtz-Platz 1 Eggenstein-Leopoldshafen 76344 Germany Priedemann Fassadenberatung GmbH Am Wall 17 Großbeeren/Berlin 14979 Germany

TABSOLARⓇ elements are novel (solar) thermal components made from ultra-high performance concrete (UHPC) which can be used as designable glazed or unglazed façade cladding elements or thermo-active building syste... 详细信息

TABSOLAR^Ⓡ elements are novel (solar) thermal components made from ultra-high performance concrete (UHPC) which can be used as designable glazed or unglazed façade cladding elements or thermo-active building systems for heating and/or cooling. They are produced with an innovative production technology which is developed in a current research project together with appropriate system concepts. In order to simplify the system design process and visualize possible TABSOLAR^Ⓡ façades on site, new software tools are being developed. Finally, a demonstration façade will be installed on a renovated two-family residential building. The ongoing interactive design process of this first use case is an important part of the project and the overall TABSOLAR^Ⓡ concept. © 2022

关键词： Architecture Augmented reality BIM Bionics Configurator FracThermⓇ Heat pump Rear-ventilated façade Solar thermal façade collector TABSOLARⓇ Thermo-active building systems (TABS) Ultra-high performance concrete (UHPC)

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Looking Deep inside the Cathode of Li-O2 Batteries: Unraveling the Local Distribution of Li2O2 with a Combined Experimental and Model-Based Approach

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ECS Meeting Abstracts 2020年第2期MA2020-01卷

作者： Sven Kynast Daniel Langsdorf Julian Kreißl Daniel Schröder Daniela Fenske Markus Osenberg André Hilger Fabian Kubannek Ulrike Krewer TU Braunschweig Institute of Physical Chemistry Justus Liebig University Giessen Justus-Liebig-Universität Giessen Germany Fraunhofer IFAM Helmholtz-Zentrum Berlin TU Braunschweig Institute of Energy and Process Systems Engineering

Carbon-based, high surface area gas diffusion electrodes (GDEs) are commonly used as cathodes in Li-O2 batteries. These GDEs provide an sufficient amount of active sites to deposit the main discharge product, Li2O2. Despite the fast electron transfer at the electrode surface to form Li2O2, experimental results show that the very high theoretical energy densities of Li-O2 batteries cannot be achieved at the moment. Instead of the desired formation of high amounts of soluble LiO2, predominantly insoluble Li2O2 precipitates at the active sites of the cathode during discharge. Unfortunately Li2O2 is poorly conductive for electrons, which leads to a low amount of deposited Li2O2 per active site and a fast passivation of the cathode. Thus, only the cathode surface area and not the pore volume is utilized by Li2O2, which explains the discrepancy between theory and experiments. Furthermore, the precipitation leads to continuous changes in porosity, available active surface area and predominant reaction pathway. For this reason a detailed analysis of the distribution of Li2O2 at all points in the GDE and of the factors that influence the Li2O2 morphology is needed to overcome performance limitations. [1] In this work, we elucidate how the local distribution of Li2O2 inside the GDE and its particle size evolve as a function of discharge current density. We apply a powerful combination of experimental and model-based analysis. To the best of our knowledge, this is the first study on the cathode surface utilization by Li2O2 and its particle sizes performed for different locations and states of discharge (SOD). The impact of the distribution and the resulting changes in transport resistance and active surface area on the battery performance are derived thereof. In the experimental part, decreasing capacities and Li2O2 particle sizes are observed for increasing discharge current densities (see SEM analysis of discharged battery cathodes in fig. 1 a)). Furthermore, the experimenta

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