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Reconfiguration and dissociation of bonded hydrogen in silicon by energetic ions

Physical Review B 2011年第4期83卷 045204-045204页

作者： S. V. S. Nageswara Rao S. K. Dixit G. Lüpke N. H. Tolk L. C. Feldman Department of Physics Pondicherry University Puducherry 605014 India Department of Physics and Astronomy Vanderbilt University Nashville Tennessee 37235 USA Interdisciplinary Materials Science Program Vanderbilt University Nashville Tennessee 37235 USA Vanderbilt Institute of Nanoscale Science and Engineering Vanderbilt University Tennessee TN 37235 USA Department of Applied Science College of William and Mary Williamsburg Virginia 23187 USA Institute for Advanced Materials Devices and Nanotechnology Rutgers University Piscataway NJ 08901

We report in situ infrared measurements of ion-induced reconfiguration and dissociation of bonded hydrogen associated with various defects in silicon at low temperatures. Defect-associated Si-H complexes were prepared by low-temperature proton implantation in silicon followed by room-temperature annealing. As a result of subsequent low-temperature He3 ion irradiation, we observed (1) ion-induced dissociation of Si-H complexes, (2) a notable difference in the dissociation rate of interstitial- and vacancy-type defects, and, unexpectedly, (3) the growth of bond-centered hydrogen, which is generally observed in association with low-temperature proton implantation. These findings provide insight into the mechanisms responsible for the dissociation of hydrogen bonds in silicon and thus have important implications for bond-selective nanoscale engineering and the long-term reliability of state-of-the-art silicon semiconductor and photovoltaic devices.

关键词： HYDROGEN SILICON PROTONS SEMICONDUCTORS PHOTOVOLTAIC power generation

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On the plastic anisotropy of an aluminium alloy and its influence on constrained multiaxial flow

On the plastic anisotropy of an aluminium alloy and its infl...

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作者： Fourmeau, M. Børvik, T. Benallal, A. Lademo, O.G. Hopperstad, O.S. Department of Structural Engineering Norwegian University of Science and Technology Rich. Birkelands vei 1A NO-7491 Trondheim Norway LMT-cachan ENS de Cachan/CNRS/UPMC/PRES Universud 61 avenue du Président Wilson 94235 Cachan cedex France Norwegian Defence Estates Agency Research and Development Department PB 405 Sentrum NO-0103 Oslo Norway SINTEF Materials and Chemistry Applied Mechanics and Corrosion Richard Birkelandsvei 2 NO-7465 Trondheim Norway

The influence of plastic anisotropy on the mechanical behaviour of a rolled aluminium plate under quasi-static loading conditions is studied experimentally and numerically. Material tests in different directions with respect to the rolling direction of the plate were carried out on various specimen shapes providing a wide range of stress states. The Yld2004-18p anisotropic yield function was identified through uniaxial tensile tests, shear tests and upsetting tests. This yield function was found to provide an adequate description of the significant anisotropic behaviour of a high-strength AA7075-T651 plate. Numerical simulations of all the material tests were then performed with an elasto-plastic material model using both the anisotropic and an isotropic version of the yield function. The numerical predictions of the mechanical response for notched tensile tests obtained with the isotropic version of the material model clearly over-estimated the experimental results. Similar results have been reported in the literature on other materials using isotropic constitutive relations. This over-estimation was significantly reduced when using the anisotropic version of the material model, and the reason why plastic anisotropy is so important for an accurate prediction of the notch-strengthening effect is explained. It was also established that the exponent of the yield function Yld2004-18p has a strong influence on the results for the notched tensile tests. When the exponent of the yield surface was assigned a sufficiently high value, an almost perfect fit between the numerical predictions and the experimental results was obtained. © 2011 Elsevier Ltd. All rights reserved.

关键词： Forecasting

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Investigation on continuous wave laser performance of a-cut Tm,Ho:YAlO 3 crystal at room temperature

Investigation on continuous wave laser performance of a-cut ...

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2011 Symposium on Photonics and Optoelectronics, SOPO 2011

作者： Yang, K.J. Bromberger, H. Dekorsy, T. Zheng, L.H. Xu, J. Zhao, G.J. Department of Physics Center of Applied Photonics University of Konstanz 78457 Konstanz Germany School of Information Science and Engineering Shandong University 250100 China Max Planck Research Department for Structural Dynamics University of Hamburg-CFEL Germany Key Laboratory of Transparent and Opto-functional Inorganic Materials Shanghai Institute of Ceramics Chinese Academy of Sciences 215 Chengbei Road Shanghai 201800 China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences No.390 Qinghe Road Shanghai 201800 China

ISBN: (纸本)9781424465545

An experimental investigation on the laser performance of an a-oriented Tm,Ho:YAlO3 crystal end-pumped by a wavelength tunable Ti:Sapphire laser is presented in this paper. Single- and dual-wavelength operations of Tm,Ho:YAlO3 lasers have been investigated in detail. Maximum output powers of 890mW at 2119nm, 836mW at 2103nm and 487mW at 2130nm for the a-oriented Tm,Ho:YAlO3 crystal have been obtained, corresponding to optical conversion efficiencies of 32% and 31% and 18% in terms of absorbed pump power, respectively. The maximum slope efficiency reaches 45.9% when the laser runs at 2119nm. © 2011 IEEE.

关键词： Solid state lasers

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DC and AC Gate-Bias Stability of Nanocrystalline Silicon Thin-Film Transistors Made on Colorless Polyimide Foil Substrates

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MRS Online Proceedings Library (OPL) 2011年第1期1321卷 mrss11-1321-a22-03-mrss11-1321-a22-03页

作者： I-Chung Chiu I-Chun Cheng Jian Z. Chen Jung-Jie Huang Yung-Pei Chen Graduate Institute of Photonics and Optoelectronics National Taiwan University Taipei 10617 Taiwan Department of Electrical Engineering National Taiwan University Taipei 10617 Taiwan Institute of Applied Mechanics National Taiwan University Taipei 10617 Taiwan Department of Materials Science and Engineering MingDao University Changhua 52345 Taiwan Display Technology Center Industrial Technology Research Institute Hsinchu 31040 Taiwan

Staggered bottom-gate hydrogenated nanocrystalline silicon (nc-Si:H) thin-film transistors (TFTs) were demonstrated on flexible colorless polyimide substrates. The dc and ac bias-stress stability of these TFTs were investigated with and without mechanical tensile stress applied in parallel to the current flow direction. The findings indicate that the threshold voltage shift caused by an ac gate-bias stress was smaller compared to that caused by a dc gate-bias stress. Frequency dependence of threshold voltage shift was pronounced in the negative gate-bias stress experiments. Compared to TFTs under pure electrical gate-bias stressing, the stability of the nc-Si:H TFTs degrades further when the mechanical tensile strain is applied together with an electrical gate-bias stress.

关键词： plasma-enhanced CVD (PECVD) (deposition) Si thin film

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Electronic bands coupling enhanced Raman scattering in FeCl3-intercalated few-layer graphene

Electronic bands coupling enhanced Raman scattering in FeCl3...

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第三届亚洲光谱会议

作者： Da Zhan Xiao-Feng Fan Lei Liu Jia-Xu Yan Li Sun Ya-Nan Xu Ting Yu Zhen-Hua Ni Ze-Xiang Shen Division of Physics and Applied Physics School of Physical and Mathematical SciencesNanyang Technological University College of Materials Science and Engineering Jilin University Key Laboratory of Excited State Processes Changchun Institute of OpticsFine Mechanics and Physics (CIOMP) Department of Physics Southeast University

Graphene,an atomic carbon layer arranged in sp2 style has attracted enormous interest due to its excellent electronic,magnetic and thermal ***,much of the unique properties of graphene are accorded to that of single l... 详细信息

关键词： Raman Graphene Electronic bands coupling enhanced Raman scattering in FeCl3-intercalated few-layer graphene

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SQUARAINE DONORS FOR HIGH EFFICIENCY SMALL MOLECULE SOLAR CELLS

SQUARAINE DONORS FOR HIGH EFFICIENCY SMALL MOLECULE SOLAR CE...

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IEEE Photovoltaic Specialists Conference

作者： Guodan Wei Siyi Wang Xin Xiao C. Kyle Renshaw Lincoln Hall Vyacheslav V. Diev Mark E. Thompson Stephen R. Forrest Department of Materials Science and Engineering University of Michigan Department of Chemistry University of Southern California Department of Electrical Engineering and Computer Science University of Michigan Applied Physics Program University of Michigan

ISBN: (纸本)9781424499663

It has been a challenge to achieve high efficiency organic photovoltaics (OPV) that absorb long wavelength solar radiation without incurring unacceptable reductions in open circuit voltage (V_(oc)) or charge separation efficiency. Based on the parent structure of the 2, 4-bis[4-(N, N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (SQ), we have increased V_(oc) using a family of highly near-infrared absorbing SQs, achieving values as high as 0.94 V. These SQ donors are: 2, 4-bis[4-(N-Phenyl-1-naphthylamino)-2,6-dihydroxyphenyl] squaraine (1-NPSQ),2,4-bis[4-(N,N-diphenylamino)-2,6 dihydroxyphenyl] squaraine (DPSQ), 2,4-bis[4-(N,N-diphenylamino)-2,6-dihydroxyphenyl] asymmetric squaraine (DPASQ). The spin-cast SQ, 1-NPSQ, DPSQ and DPASQ donors are then coated with the acceptor C_(60) to form bulk heterojunction (BHJ) solar cells that take advantage of their exceptionally high absorption coefficient and nanocrystalline morphology to overcome the short diffusion length characteristic of these materials. Combined with a high short-circuit current density (J_(sc)=10.6 mA/cm~2) and high fill factor (FF=0.64), the optimized 1-NPSQ/C_(60) photovoltaic cells with 1-NPSQ annealed at elevated temperature have a power conversion efficiency of η_p as high as 6.0% (correcting for solar mismatch) at 1 sun (AM 1.5G) simulated solar illumination, which to our knowledge is the highest efficiency reported to date for small molecule OPVs.

关键词： Photovoltaic cells Absorption Annealing Educational institutions Sun USA Councils Heterojunctions

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Equilibrium iteration algorithm for analyzing fluid-structure problems using ALE finite element method

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Hedongli Gongcheng/Nuclear Power engineering 2011年第SUPPL. 1期32卷 137-140页

作者： Liu, Li-Ling Yi, Li-Qing Wei, Yong-Tao School of Materials Science and Engineering Southwest Jiaotong University Chengdu 610031 China Department of Applied Mechanics College of Architecture and Environment Sichuan University Chengdu 610065 China

Based on the Galerkin/Least squares finite element method under arbitrary Lagrange-Euler description, the equilibrium iteration algorithm in which forces applied by fluids onto rigid bodies are treated as converging parameter is established for analyzing the fluid-solid interaction problems, and a new algorithm of mesh updating on the basis of pseudo-elasticity method is proposed which can maintain fluid elements sides straight with mid-nodes coinciding with the center of element sides during mesh motion. The numerical example is about a mass-spring system vibrating freely in closed fluids which is analyzed with the method proposed, and the equivalent damping ratio, added-mass introduced by fluid-solid interaction are obtained as well as the streamlines of flow and pressure contours.

关键词： Finite element method

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Development of continuous wrapping tantalum barriers for internal-tin Nb3Sn multi-filamentary wires

Development of continuous wrapping tantalum barriers for int...

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International Conference on applied Superconductivity and Electromagnetic Devices, ASEMD

作者： Wu Ming Chen Mustafa Yavuz Xue Kui Fu Shiro Kambe Peter McIntyre Jian Xun Jin Waterloo Institute for Nanotechnology University of Waterloo Waterloo ONT Canada School of Materials Science & Engineering University of New South Wales Sydney NSW Australia Human Sensing Program Graduate School of Science and Engineering Yamagata University Yonezawa Japan Waterloo Institute for Nanotechnology University of Waterloo Cankaya University Ankara ON Turkey Department of Physics Texas A&M University TX USA Center of Applied Superconductivity and Electrical Engineering University of Electronic Science and Technology of China China

A process, continuous wrapping tantalum barrier, has been developed and investigated in order to reduce the manufacturing cost. By avoiding inserting expensive tantalum tube, a long sheet barrier was directly used to wrap a prior restack. In this work, a tantalum barrier with 20 % overlap was wrapped onto sub-elements. Then 18-filament Nb 3 Sn plus 1 copper core restack billet was successfully drawn down and extruded into round wire as thin as a diameter of 0.84 mm. The longitudinal and cross-sectional images revealed most of barriers were continuous and intact. However, further experiments are needed to optimize the process in order to keep the all barriers continuous and intact after manufacturing.

关键词： Niobium-tin Wires Copper Electron tubes Educational institutions Superconducting magnets

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Dynamic Embrittlement: Quasi-Static Interfacial Decohesion

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MRS Online Proceedings Library 2011年第1期586卷 303-303页

作者： C. J. Mcmahon J. L. Bassani Y. Mishin Department of Materials Science and Engineering University of Pennsylvania Philadelphia USA Department of Mechanical Engineering and Applied Mechanics University of Pennsylvania Philadelphia USA Department of Materials Science and Engineering Virginia Polytechnic Institute & State University Blacksburg USA

In a surprising variety of cases, interfaces in normally ductile materials can undergo timedependent brittle cracking under the influence of a tensile stress, either applied externally or existing as an internal residual stress. The connecting feature in all these cases is the presence of a surface-adsorbed element that is highly mobile in comparison to the constituent elements of the material. As in the phenomena of diffusion creep and diffusive growth of cavities at high temperatures, the driving force for this cracking is the work done by the tensile stress when a surface atom enters the solid. At temperatures below about 0.5 Tm of the solid, this occurs mainly along grain boundaries. Examples of systems that have been studied in some detail include cracking of alloy steels by sulfur, Cu-Sn alloys by tin, and nickel-based alloys by oxygen. Because the cracking involves diffusive penetration along grain boundaries, the rate of cracking is highly sensitive to grain-boundary structure and composition, and these variables offer opportunities to control the problem. We are aiming at a quantitative understanding of the effects of grain-boundary structure, stress, and temperature on this phenomenon by crack-growth experiments on bicrystals, by atomistic modeling of the stress-driven diffusion, and by micromechanical modeling of the events occurring at the tip of a growing crack.

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PREDICTIVE APPROACH TO FAILURE OF COMPOSITE LAMINATES WITH EQUIVALENT CONSTRAINT MODEL

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Acta Mechanica Solida Sinica 2010年第3期23卷 240-247页

作者： Fang Wang Xiangguo Zeng Junqian Zhang School of Materials Science and Engineering Southwest University Chongqing 400715 China School of Architecture and Environment Sichuan University Chengdu 610065 China Department of Mechanics and Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

This work established a new analytical model based upon the equivalent constraint model （ECM） to constitute an available predictive approach for analyzing the ultimate strength and simulating the stress/strain response of general symmetric laminates subjected to combined loading, by taking into account the effect of matrix cracking. The ECM was adopted to mainly predict the in-plane stiffness reduction of the damaged laminate. Basic consideration that progressive matrix cracking provokes a re-distribution of the stress fields on each lamina within laminates, which greatly deteriorates the stress distributed in the primary load-bearing lamina and leads to the final failure of the laminates, is introduced for the construction of the failure criterion. The effects of lamina properties, lay-up configurations and loading conditions on the behaviors of the laminates were examined in this paper. A comparison of numerical results obtained from the established model and other existed models and published experimental data was presented for different material systems. The theory predictions demonstrated great match with the experimental observations investigated in this study.

关键词： composite laminates equivalent constraint model primary load-bearing lamina progressive matrix cracking strength

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