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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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Fabrication of uniform QPM device using negative multiple pulse poling method

Fabrication of uniform QPM device using negative multiple pu...

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International Conference on Quantum Electronics (IQEC)

作者： Ju Won Choi Heejong Kang Do-Kyeong Ko Jung Hoon Ro Nan Ei Yu Graduate program of Photonics and Applied Physics Gwangju Institute of Science and Technology Gwangju South Korea Advanced Photonics Research Institute Gwangju Institute of Science and Technology Gwangju South Korea Department of Biomedical Engineering School of Medicine Pusan National University Busan South Korea

We introduced a novel negative multiple pulse poling (NMP) method for uniform device fabrication of quasi-phase matching using an in-situ visualization system. Diffraction pattern analysis showed the duty ratio of 0.4... 详细信息

ISBN: (纸本)9780977565771

关键词： Diffraction Lithium niobate Visualization Crystals Optical diffraction Resists Real time systems

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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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Nanocellulosic materials and nanocomposites

Nanocellulosic materials and nanocomposites

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International Conference on Nanotechnology for the Forest Products Industry 2010

作者： Niska, Kristiina Oksman Luteå University of Technology Department of Applied Physics and Mechanical Engineering Luleå Sweden

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The Self-Healing Capability of Carbon Fibre Composite Structures Subjected to Hypervelocity Impacts Simulating Orbital Space Debris

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International Scholarly Research Notices 2012年第1期2012卷

作者： B. Aïssa K. Tagziria E. Haddad W. Jamroz J. Loiseau A. Higgins M. Asgar-Khan S. V. Hoa P. G. Merle D. Therriault F. Rosei Department of Smart Materials and Sensors for Space Missions MPB Technologies Inc. 151 Hymus Boulevard Pointe-Claire Montreal QC Canada H9R 1E9mpb-technologies.ca Shock Waves Physics Group and Department of Mechanical Engineering McGill University Montreal QC Canada H3A 0G4mcgill.ca Concordia Center for Composites Department of Mechanical and Industrial Engineering Concordia University Montreal QC Canada H3G 2M8concordia.ca Center for Applied Research on Polymers (CREPEC) Mechanical Engineering Department École Polytechnique de Montréal P.O. Box 6079 Station “Centre-Ville” Montreal QC Canada H3C 3A7polymtl.ca Department of Chemistry and Biochemistry Concordia University Canada H3G 2M8concordia.ca The Quality Engineering Test Establishment Department of National Defence Ottawa ON Canada K1A 0K2dnd.ca Institut National de la Recherche Scientifique INRS-Énergie Matériaux et Télécommunications 1650 Blvd Lionel Boulet CP Varennes QC Canada J3X 1S2inrs.ca

The presence in the space of micrometeoroids and orbital debris, particularly in the lower earth orbit, presents a continuous hazard to orbiting satellites, spacecrafts, and the international space station. Space debris includes all nonfunctional, man-made objects and fragments. As the population of debris continues to grow, the probability of collisions that could lead to potential damage will consequently increase. This work addresses a short review of the space debris “challenge” and reports on our recent results obtained on the application of self-healing composite materials on impacted composite structures used in space. Self healing materials were blends of microcapsules containing mainly various combinations of a 5-ethylidene-2-norbornene (5E2N) and dicyclopentadiene (DCPD) monomers, reacted with ruthenium Grubbs′ catalyst. The self healing materials were then mixed with a resin epoxy and single-walled carbon nanotubes (SWNTs) using vacuum centrifuging technique. The obtained nanocomposites were infused into the layers of woven carbon fibers reinforced polymer (CFRP). The CFRP specimens were then subjected to hypervelocity impact conditions—prevailing in the space environment—using a home-made implosion-driven hypervelocity launcher. The different self-healing capabilities were determined and the SWNT contribution was discussed with respect to the experimental parameters.

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Tuning the electronic effective mass in double-doped SrTiO3

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Physical Review B 2011年第3期83卷 035101-035101页

作者： J. Ravichandran W. Siemons M. L. Scullin S. Mukerjee M. Huijben J. E. Moore A. Majumdar R. Ramesh Applied Science and Technology Graduate Group University of California Berkeley California 94720 USA Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Department of Physics University of California Berkeley California 94720 USA Department of Materials Science and Engineering University of California Berkeley California 94720 USA Department of Physics Indian Institute of Science Bangalore 560012 India Faculty of Science and Technology and MESA+ Institute for Nanotechnology University of Twente P.O. Box 217 NL-7500AE Enschede The Netherlands Department of Mechanical Engineering University of California Berkeley California 94720 USA

We elucidate the relationship between effective mass and carrier concentration in an oxide semiconductor controlled by a double-doping mechanism. In this model oxide system, Sr1−xLaxTiO3−δ, we can tune the effective mass ranging from 6 to 20me as a function of filling (carrier concentration) and the scattering mechanism, which are dependent on the chosen lanthanum- and oxygen-vacancy concentrations. The effective mass values were calculated from the Boltzmann transport equation using the measured transport properties of thin films of Sr1−xLaxTiO3−δ. We show that the effective mass decreases with carrier concentration in this large-band-gap, low-mobility oxide, and this behavior is contrary to the traditional high-mobility, small-effective-mass semiconductors.

关键词： EFFECTIVE mass (physics) OXIDES SEMICONDUCTORS LANTHANUM compounds TRANSPORT theory (Mathematics) THIN films

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Phonon Transport and Thermoelectricity in Defect-Engineered InAs Nanowires

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MRS Online Proceedings Library 2011年第1期1404卷 36-43页

作者： Weathers, Annie Moore, Arden L. Pettes, Michael T. Salta, Daniel Kim, Jaehyun Dick, Kimberly Samuelson, Lars Linke, Heiner Caroff, Philippe Shi, Li Department of Mechanical Engineering The University of Texas at Austin Austin USA Center for Nano and Molecular Science The University of Texas at Austin Austin USA Material Science and Engineering Graduate Program The University of Texas at Austin Austin USA The Nanometer Structure Consortium (nmC@LU) and Division of Solid State Physics Lund University Lund Sweden Polymer & Materials Chemistry Lund Sweden Institut d’Electronique de Microelectronique et de Nanotechnologie UMR CNRS 8520 France

There have been reports of improvements in the thermoelectric figure of merit through the use of nanostructured materials to suppress the lattice thermal conductivity. Here, we report on a fundamental study of the combined effects of defect planes and surface scattering on phonon transport and thermoelectric properties of defect-engineered InAs nanowires. A microfabricated device is employed to measure the thermal conductivity and thermopower of individual suspended indium arsenide nanowires grown by metal organic vapor phase epitaxy. The four-probe measurement device consists of platinum resistance thermometers and electrodes patterned on two adjacent SiNx membranes. A nanowire was suspended between the two membranes, and electrical contact between the nanowire and the platinum electrodes was made with the evaporation of a Ni/Pd film through a shadow mask. The exposed back side of the device substrate allows for characterization of the crystal structure of the suspended nanowire with transmission electron microscopy (TEM) following measurement. The 100-200 nm diameter zincblende (ZB) InAs nanowire samples were grown with randomly spaced twin defects, stacking faults, or phases boundaries perpendicular to the nanowire growth direction, as revealed by transmission electron microscopy (TEM) analysis. Compared to single-crystal ZB InAs nanowires with a similar lateral dimension, the thermal conductivity of the defect-engineered nanowires is reduced by fifty percent at room temperature.

关键词： thermoelectric nanostructure thermal conductivity

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Structural properties of Eu doped GaN and its relation with luminescence properties

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MRS Online Proceedings Library (OPL) 2011年第1期831卷 E3.28-E3.28页

作者： Hyungjin Bang Takahiro Maruyama Shigeya Naritsuka Katsuhiro Akimoto 21st Century COE program “Nano Factory” Meijo University 1–501 Shiogamaguchi Tempaku-ku Nagoya 468–8502 Japan Department of materials science and engineering Meijo University 1–501 Shiogamaguchi Tempaku-ku Nagoya 468–8502 Japan Institute of applied physics University of Tsukuba Tennodai 1–1–1 Tsukuba Ibaraki 305–8573 Japan

The Structural properties of Europium (Eu) doped GaN and its relation with optical properties were studied. Concentration quenching of the intensity of the Eu related luminescence observed when Eu concentration exceeds 3 at.%. In situ reflection high-energy electron diffraction (RHEED), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were carried out to study this luminescence quenching and it was discovered that there is close relationship between the luminescence intensity at 622 nm and structural properties. The cause of the concentration quenching is likely related to the polycrystalline growth as well as to the EuN formation.

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Implications of signal intensity fluctuations on vector sensor array processing

Implications of signal intensity fluctuations on vector sens...

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MTS/IEEE Seattle, OCEANS 2010

作者： Dall'Osto, David R. Dahl, Peter H. Department of Mechanical Engineering Applied Physics Laboratory University of Washington Seattle WA 98105 United States

ISBN: (纸本)9781424443321

Vector sensor processing relies on the covariance matrix for both a single vector sensor and a larger matrix from a vector sensor array. The elements of these covariance matrices have physical interpretation in terms of complex intensity. The presence of reactive intensity on the array shows up in the off diagonal elements of the covariance matrix and has significant implications on direction of arrival (DOA) algorithms. Sources of reactive intensity in an underwater waveguide are dependent on the geometry of the system and fluctuations in these quantities affect the ability to increase the array aperture to better resolve arrival angles. ©2010 IEEE.

关键词： Covariance matrix

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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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