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Threading dislocation density comparison between GaN grown on the patterned and conventional sapphire substrate by high resolution X-ray diffraction

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Science china(physics,Mechanics & Astronomy) 2010年第3期53卷 465-468页

作者： ZHANG YuChao1, XING ZhiGang2. MA ZiGuang2. CHEN Yao2. DING GuoJian2. XU PeiQiang2. DONG ChenMing3, CHEN Hong2.& LE XiaoYun1 1 School of physics and nuclear {2. Engineering, Beihang University, beijing 100190, china 2.Renewable {2. Laboratory, institute of physics, Chinese Academy of Sciences, beijing 100190, china 3 School of Information and Communication, Tianjin Polytechnic University, Tianjin 300160, china 1. School of physics and nuclear {2. Engineering Beihang University Beijing 100190 China2. Renewable Energy Laboratory Institute of Physics Chinese Academy of Sciences Beijing 100190 China3. School of Information and Communication Tianjin Polytechnic University Tianjin 300160 China

GaN epifilms are grown on the patterned sapphire substrates (PSS) (0001) and the conventional sapphire substrates (CSS) (0001) by metal-organic chemical vapor deposition (MOCVD) using a novel two-step growth. High resolution X-ray diffraction (HR-XRD) is used to investigate the threading dislocation (TD) density of the GaN epifilms. The TD density is calculated from the ω-scans full width at half maximum (FWHM) results of HR-XRD. The edge dislocation destiny of GaN grown on the PSS is 2.7×108 cm-2. which is less than on the CSS. This is confirmed by the results of atomic force microscopy (AFM) measurement. The lower TD destiny indicates that the crystalline quality of the GaN epifilms grown on the PSS is improved compared to GaN epifilms grown on the CSS. The residual strains of GaN grown on the PSS and CSS are compared by Raman Scattering spectra. It is clearly seen that the residual strain in the GaN grown on PSS is lower than on the CSS.

关键词： GaN patterned sapphire substrate threading dislocation XRD

THE atomic WEIGHT OF CERIUM

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Chinese Chemical Letters 1994年第4期5卷 357-360页

作者： Tsing Lien CHANG.(department of Chemistry, Peking University, beijing 100871)Yong Fu LIU({2. institute of nuclear energy, beijing 102413)

Isotopic ratio measurement was carried out for cerium on a thermal ionization mass spectrometer, which was calibrated by using a europium standard as substitute, yielding a new value of the atomic weight of cerium as ...

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HIGH-energy PROTON IRRADIATION EFFECTS ON GaAs/Ge SPACE SOLAR CELLS

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Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 463-466页

作者： R. Wang (The Key Laboratory of Beam Technology and Materials Modification of Ministry of Education, institute of Low energy {2. physics, beijing Normal University beijing Radiation Center, beijing 100875, china) S.D. Yao (department of Technical Phys Inst. of energy Nucl. Phys. Beijing Normal Univ. Beijing 100875 China

This paper reports the high-energy proton irradiation effects on GaAs/Ge space solar cells. The solar cells were irradiated by protons with energy of 5-2. MeV at fluence ranging from 1×109 to 7×1013 cm-2. and then their electric parameters were measured at AM0. It was shown that the Isc, Voc and Pmax decrease as the proton energy increasing, and the degradation is relative to proton irradiation-induced defect with a level of Ec-0.41 eV in irradiated GaAs/Ge cells.

关键词： Germanium High energy physics Irradiation Protons Semiconducting gallium arsenide

Consecutive reversible ionization-recombination reactions and ionic charge state distribution of Au plasma

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Science china(physics,Mechanics & Astronomy) 2005年第5期48卷 575-584页

作者： ZHU Zhiyan1, ZHU Zhenghe1, TANG Changhuan1, TANG Yongjian2.& GAO Tao1 1. institute of atomic and Molecular {2., Sichuan University, Chengdu 610065, china 2. china Academy of Engineering {2., Mianyang 62.900, china 1. institute of atomic and Molecular {2. Sichuan University 610065 Chengdu China 2. china Academy of Engineering physics 621900 Mianyang China

The present work proposes kinetics of ionization-recombination to study the charge state distribution of Au plasma. The first step is to calculate the average lifetime, energy level structure, degeneracy and partition function of Au48+―Au52. by relativistic quantum mechanics, and next to compute the equilibrium constant and the second-order recombination rate constant by statistical thermodynamics. Based on these data, the differential equations of consecutive reversible ionization-recombination reactions are solved from which the charge state distribution and its average charge are derived. Finally, the influence of electron temperature and density on average charge is given in this paper. It is called the first-principle theory, for no experimental data are needed.

关键词： Au plasma, ionization-recombination dynamics, ionic charge state distribution, average charge.

Photoionization Cross Section and Resonance Structure of Mn+

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Communications in Theoretical physics 2006年第5期45卷 911-913页

作者： LU Peng-Fei,~1 LIU Jin-Chao,~2.and YANG Xiang-Dong~2.~1 School of Science, beijing University of Posts and Telecommunication, beijing 100876,{2. ~2.institute of atomic and Molecular physics, Sichuan University, Chengdu 610065,{2. School of Science Beijing University of Posts and Telecommunication institute of atomic and Molecular {2. Sichuan University

A photoionization cross section calculation of Mn;is performed in the formalism of many-body perturbation theory for photon energies ranging from 48 eV to 56 eV. We consider excitations from the 3p, 3d, and 4s subshells. The effects of the strong 3p→3d and 3p→4s transitions are included as resonant contributions to the total cross sections. Good agreement with experiment is found.

关键词： many-body perturbation theory effective single-particle potential generalized resonance method

The anharmonic effect study of coupled Morse oscillators for the unimolecular reaction

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Science china Chemistry 2008年第12期51卷 1146-1152页

作者： YAO Li1,2.& LIN Sheng-Hsien2.31 department of physics, Dalian Maritime University, Dalian 11602.,{2. 2.institute of atomic and Molecular Sciences, Academia Sinica, Taipei 10764,{2. 3 department of Applied Chemistry and institute of Molecular Sciences, Chiao-Tung University, Hsinchu 30051, Taiwan,{2. 1. department of physics Dalian Maritime University Dalian 116026 China 2. institute of atomic and Molecular Sciences Academia Sinica Taipei 10764 China 3. department of Applied Chemistry and institute of Molecular Sciences Chiao-Tung University Hsinchu 30051 Taiwan China

The importance of anharmonic effect in dissociation of molecular systems especially clusters has been noted. In this paper, we shall study the effect of coupled anharmonic oscillator of the standard bilinear form (SBF) Morse oscillator (MO) potential on unimolecular reaction. We shall use the systematic theoretical approach, YL method, proposed by Yao and Lin (YAO L, et. al. J Phys Chem A, 2.07, 111(2.): 672.-672.), which can evaluate anharmonic effects on the rate constants based on the transition state theory. In treating the anharmonic effect with the Morse oscillator potential on unimolecular reactions under collision-free conditions by using the RRKM (Rice-Ramsperger-Kassel-Marcus) theory, the in-verse Laplace transformation of the partition functions was used to obtain the total amount of state and density of state by using the first-order and the second-order approximations of the saddle-point method. To demonstrate the anharmonic effect of the SBF Morse model, we choose some model systems and a real reaction as examples.

关键词： anharmonic effect standard bilinear form Morse oscillator rate constant RRKM theory

Analyses of p-^(11)B,p-^(11)C and d-^(11)C Reactions

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Chinese journal of nuclear physics 1995年第1期17卷 60-66页

作者： Shen Qing-biao Zhang Jing-shang Han Yin-lu Bai Xi-xiang (china institute of {2. energy,P.O.Box 2.5(41),beijing 102413) 中国原子能科学院北京

Aiming at the production of 11C radioactive beam,various nuclear data ofp+11B reaction at incident proton energies spanning 1-2. MeV were obtained by calcu-lation with quasiquantum multistep direct （QMSD） theory and Hauser-Feshbach （HF）*** calculations basically agree with the experimental *** angular distri-butions in lab frame of 11C produced in the reversed geometry reaction 1H(11B,11C)nwere *** cross sections of p+11C and d+11C reactions induced by 11C beamwere also *** results show that the experimental measurement for 11C+d re-action is more feasible than for 11C+p reaction at HI-13 tandem accelerator.

关键词： 11C Radioactive beam Analyses

Analyses of d-^(6,7)Li and d-^(7,9)Be Reactions

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Chinese journal of nuclear physics 1997年第2期19卷 103-109页

作者： Han Yinlu Shen Qingbiao Zhang Jingshang Liu Weiping Bai Xixiang china institute of atomic energy,P.O.Box 2.5(41),beijing {2.Zhang Zhengjun Sun Xiuquan department of physics,Northwest University,Xian 710069 中国原子能科学院北京西北大学物理系陕西西安

Aiming at the production of 6He,8Li and 7Be radioactive beams,various nuclear dataof d+6,7Li and d+9Be reactions at incident energies spanning 0,1～30.0 MeV are obtained bycalculation with the distorted wave Born approximation,preequilibrium nuclear reaction andHauser-Feshbach（HF）*** cross sections of d+7Be reaction are also *** show that the experimental measurement for d+7Be reaction is feasible at HI-13 tandemaccelerator.

关键词： ~6He ~8Li and ~7Be Radioactive beam

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B_c Meson Studies

高能物理与核物理 2002年第Z1期26卷 1-10页

作者： CHANG Chao-Hsi (institute of Theoretical physics, Chinese Academy of Sciences, {2. 100080, china) Inst. of Theor. Phys. Chinese Acad. of Sci. Beijing 100080 China

Our studies on the meson Bc arc briefly *** decays of the meson Bc to a P-wave charmonium Xc or hc are reported comparatively precisely because they are fresh

关键词：高能物理核物理增刊张肇西 B_c Meson Studies Rev