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Effects of Annealing Temperature on Structural and Optical Properties of ZnO Thin Films

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Chinese Physics Letters 2010年第4期27卷 227-230页

作者：徐建萍石少波李岚张晓松王雅欣陈希明 Institute of Material Physics Key Laboratory of Display Materials and Photoelectric Devices (Ministry of Education) Tianjin University of Technology Tianjin 300384 Tianjin Key Laboratory for Photoelectric Materials and Devices Tianjin University of Technology Tianjin 300384 Department of Mathematics and Physics Tianjin University of Technology and Education Tianjin 300222 School of Electronic Information and Communication Engineering Tianjin University of Technology Tianjin 300384

The effects of annealing temperature on the structural and optical properties of ZnO films grown on Si （100） substrates by sol-gel spin-coating are investigated. The structural and optical properties are characterized by x-ray diffraction, scanning electron microscopy and photoluminescence spectra. X-ray diffraction analysis shows the crystal quality of ZnO films becomes better after annealing at high temperature. The grain size increases with the temperature increasing. It is found that the tensile stress in the plane of ZnO films first increases and then decreases with the annealing temperature increasing, reaching the maximum value of 1.8 GPa at 700℃. PL spectra of ZnO films annealed at various temperatures consists of a near band edge emission around 380 nm and visible emissions due to the electronic defects, which are related to deep level emissions, such as oxide antisite （OZn）, interstitial oxygen （Oi）, interstitial zinc （Zni） and zinc vacancy （VZn^-）, which are generated during annealing process. The evolution of defects is analyzed by PL spectra based on the energy of the electronic transitions.

关键词： Condensed matter: electrical magnetic and optical Semiconductors Surfaces interfaces and thin films Condensed matter: structural mechanical & thermal

mechanical Behavior of Nanometer Ni by Simulating Nanoindentation

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Chinese Physics Letters 2010年第2期27卷 203-205页

作者：汤奇恒杨天勇丁斓 State Key Laboratory of Nonliear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology Beijing 100080 The School of Civil and Environmental Engineering University of Science and Technology Beijing Beijing 100083

An indentation simulation of the crystal Ni is carried out by a molecular dynamics technique （MD） to study the mechanical behavior at nanometer scales. Indenter tips with both sphere shape and conical shape with 60° cone angle are used, and simulation samples with different crystal orientations are adopted. Some defects such as dislocations and point defects are observed. It is found that nucleated defects （dislocations, amorphous atoms） are from the local region near the pin tip or the sample surface. The temperature distribution of the local region is analyzed and it can explain our MD simulation results.

关键词： Nanoscale science and low-D systems Condensed matter: structural mechanical & thermal

Synthesizing Metastable Rocksalt-Type MgTe Based on High-Pressure Solid-State Phase Transition： A First-Principles Study

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Chinese Physics Letters 2009年第11期26卷 45-48页

作者：蔡影祥徐瑞 Department of Physics Nanchang University Nanchang 330031 State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004

The controllability;of pressure-induced structural transformation in the hexagonal wurtzite-type MgTe is studied by a first-principles pseudopotential method within the generalized gradient approximation （GGA）. Based on the transitional mechanisms of the wurtzite→NiAs and the wurtzite→rocksalt, a special method of loading biaxial pressure on the （010） and （001） planes of an orthorhombic cell is designed. At equal biaxial pressure of 2. 75 GPa, an abrupt volume collapse is found and the WZ phase transforms into an orthorhombic phase with a tiny distortion. While the pressure decreases to zero, three lattice parameters a, b and c become equal and a metastable rocksalt-type MgTe is obtained.

关键词： Condensed matter: structural mechanical & thermal

Strong-Superstrong Transition in Glass Transition of Metallic Glass

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Chinese Physics Letters 2010年第3期27卷 232-235页

作者：王丹彭鸿雁徐晓雨陈宝玲吴春雷孙民华 Key Laboratory of New Carbon-based Functional and Super-hard Materials of Heilongjiang Province School of Physics and Electronic Engineering Mudanjiang Teachers College Mudanjiang 157012 School of Physics and Electronic Engineering Harbin Normal University Harbin 150025

Dynamic fragility of bulk metallic glass （BMG） of Zr64Cu16Ni10Al10 alloy is studied by three-point beam bending methods. The fragility parameter mfor Zr64Cu16Ni10Al10 BMG is calculated to be 24.5 at high temperature, which means that the liquid is a ＂strong＂ liquid, while to be 13.4 at low temperature which means that the liquid is a ＂super-strong＂ liquid. The dynamical behavior of Zr64Cu16Ni10Al10 BMG in the supercooled region undergoes a strong to super-strong transition. To our knowledge, it is the first time that a strong-to-superstrong transition is found in the metallic glass. Using small angle x-ray scattering experiments, we find that this transition is assumed to be related to a phase separation process in supercooled liquid.

关键词： Soft matter liquids and polymers Condensed matter: structural mechanical & thermal

Nanoscale thermal Response in ZnO Varistors by Atomic Force Microscopy

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Chinese Physics Letters 2009年第10期26卷 65-67页

作者：赵坤宇曾华荣李国荣宋红章程丽红惠森兴殷庆瑞 State Key Lab of High Performance Ceramics and Superfine Structures Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050 Graduate School of the Chinese Academy of Sciences Beijing 100049

We report the application of customer-built scanning thermal microscopy （SThM） based on a commercial atomic force microscope to investigate local thermal inhomogeneity of ZnO varistors. The so-called 3ω method, generally used for measuring macroscale thermal conductivity, is set up and integrated with an atomic force microscope to probe the nanoseale thermal property. Remarkably, thermal contrasts of ZnO varistors are firstly imaged by the SThM, indicating the uniform distribution of spinel phases at triple points. The frequency-dependent thermal signal of ZnO varistors is also studied to present quantitative evaluation of local thermal conductivity of the sample.

关键词： Condensed matter: electrical magnetic and optical Semiconductors Surfaces interfaces and thin films Condensed matter: structural mechanical & thermal

Analysis of Modified Williamson-Hall Plots on GaN Layers

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Chinese Physics Letters 2011年第1期28卷 145-148页

作者： LIU Jian-Qi QIU Yong-Xin WANG Jian-Feng XU Ke YANG Hui Platform for Characterization & Test Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Suzhou 215125 Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 Graduated University of Chinese Academy of Sciences Beijing 100049

Williamson Hall （W-H） analysis is often used to separate the lateral coherence length （LCL） broadening and dislocation broadening＂ on the ω-sean with a Lorentzian distribution. However, besides the LCL broadening and dislocation broadening, curvature also can broaden the w-scan peak. Usually, the w-scan can be described by a Pseudo-Voigt （P-V） function more precisely than a Lorentzian function. Based on the P-V fit peak profile, we modify the W-H plots. Both LCL broadening and curvature broadening can be eliminated from （OOl） ω-scans plots simultaneously, and a reliable tilt can be obtained. This method is a good complementary for the existing method, but is more convenient. Although we focuse on GaN layers, the results are applicable to a wide range of other materials having mosaic structures.

关键词： Surfaces interfaces and thin films Condensed matter: structural mechanical & thermal

Design and Fabrication of an Er-Doped Silica Optical Fiber with Six Photosensitive Subcores

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Chinese Physics Letters 2009年第7期26卷 147-149页

作者：李坚王静刘鹏鲁韶华毛向桥江微微宁提纲简水生 Institute of Lightwave Technology Beijing Jiao~ong University Beijing 100044 Key Lab of All Optical Network and Advanced Telecommunication Network of EMC Beijing 3iaotong University Beijing 100044 Signal & Communicaiton Research Institute China Academy of Railway Sciences Beijing 100081 4Department of Physics Xingtai College Xingtai 054001 Department of Physics Xingtai College Xingtai 054001

A type of multi-core Er-doped photosensitive silica optical fiber （MC-EDPF） is proposed and fabricated, in which a high consistency Er-doped core is surrounded by six high consistency Ge-doped cores. The multi-core design can overcome the difficulties encountered in the design and fabrication of single-core EDPFs through a modified chemical vapor deposition method combined with solution doping technology, and there is a conflict between high consistency Er doping and high consistency Ce doping. The absorption of MC-EDPFs achieved 15.876dB/m at 1550mm and lOdB/m at 98Ohm. The refleetivity of the fiber Bragg gratings （FBCs） written directly on the MC-EDPFs is as much as 96.84%.

关键词： Optics quantum optics and lasers Condensed matter: structural mechanical & thermal

Design and Application of a Near Field Microwave Antenna for the Spin Control of Nitrogen-Vacancy Centers

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Chinese Physics Letters 2010年第3期27卷 308-311页

作者：杨丽丽刘刚钦潘新宇陈东敏 Institute of Physics Chinese Academy of Sciences Beijing 100190

Controlled manipulation of the electron spin by means of a microwave field is investigated. The near magnetic field generated by a copper wire antenna is measured experimentally and simulated theoretically, and the optimum antenna length and position are obtained. By measuring the change in the fluorescence of nitrogen-vacancy （N-V） centers in diamond after excitation with a 532 nm continuous wave laser at room temperature, it is verified that the spin of the N-V center can be effectively controlled by the microwave field.

关键词： Electronics and devices Condensed matter: structural mechanical & thermal

Comparison Study on Characteristic Regimes in Shocked Porous Materials

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Chinese Physics Letters 2010年第2期27卷 209-212页

作者：许爱国张广财李华朱建士 National Key Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsPO Box 8009-26Beijing 100088

We perform a comparison study on characteristic regimes in shocked porous materials whose mechanical properties cover a wide range. Via the Minkowski functional analysis, it is found that different materials may show the same fractional size of characteristic regimes in the shock-loading procedure, even if one uses the same threshold value to define those regimes. Characteristic regimes in the material with larger initial yield are more dispersed. For a fixed shock strength, there exists a material strength with which the shock wave reaction contributes the maximum plastic work. With the decreasing of shock strength, this material strength becomes smaller. These observations may present helpful indications for new material designs.

关键词： Condensed matter: structural mechanical & thermal