Study of Vacancy clusters and their electronic structure using positrons

利用正电子研究空位团簇及其电子结构

• 批准号: 08650762
• 负责人: HASEGAWA Masayuki
• 金额: $ 1.41万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650762/
• 关键词: Positron Annihilation; Silicon; Vacancies; First-Principles Calculation; 2D-ACAR; Silicon Carbide; 2次元角相関

The positron annihilation technique has emerged as a powerful tool to study vacancy-type defects in metals and semiconductors. Positrons are sensitively trapped at defects and are annihilated there with the surrounding electrons, conveying significant information on the local electronic environment around the defect site with the emitted two gamma photons. In this field, positron lifetime and Doppler broadening methods have been emplyed. However, a more sophisticated positron annihilation technique "two dimensinal angular correlation of annihilation (2D-ACAR)"can provide us with more significant information about the defects. In this study, 2D-ACAR experiments have been carried out on Si, SiC and their related materials. Furthermore we have made first-principles calculations for 2D-ACAR spectrum.Interesting features of 2D-ACAR distribution for singly negative divacancies in Si were studied experimentally and theoretically. Anisotropy of the distribution is successfully detected for a specimen with aligned divacancies and well repreduced by first-principles calculations based on the two-component (positron-electron) density functional theory. The present calculation demonstrates that the anisotropy reflects the characteristic distribution of electrons around the divacancies, indicating that the 2D-ACAR is an effective tool to provide microscopic information on vacancy-type defects. Very useful information has been also obtained for perfect crystals of Si, SiC,diamond and graphite, and vacancies in them.

正电子歼灭技术已成为研究金属和半导体中空位型缺陷的强大工具。正电子被敏感地捕获在缺陷处，并用周围的电子被歼灭，并在缺陷位点上传达了有关局部电子环境的重要信息，并带有两个发射的γ光子。在这一领域，正电子寿命和多普勒拓宽方法已被激发。但是，更复杂的正电子歼灭技术“ an灭的二维角相关性（2D-ACAR）可以为我们提供有关缺陷的更多重要信息。在这项研究中，已经对SI，SIC及其相关材料进行了2D-ACAR实验。此外，我们在实验和理论上研究了2D-ACAR分布的第一原理计算2D-ACAR分布的感兴趣特征。对于具有对齐的分区的样本，成功检测到了分布的各向异性，并基于两组分（potitron-Electron）密度功能理论而受到第一原理计算的良好抑制。目前的计算表明，各向异性反映了电子周围电子的特征分布，表明2D-ACAR是提供有关空位型缺陷的显微镜信息的有效工具。还获得了SI，SIC，Diamond和石墨的完美晶体以及其中的空缺的非常有用的信息。

项目成果

T.Chiba, M.Hasegawa, Z.Akahane, A.A.Manuel, M.Saito, H.Sumiya, E.Kuramoto and M.Takenaka: ""Positron 2D-ACAR Study on Diamonds : Perfect Cuystals and Defects"" Mater.Sci.Forum. 255-257. 521-523 (1997)

T.Chiba、M.Hasekawa、Z.Akahane、A.A.Manuel、M.Saito、H.Sumiya、E.Kuramoto 和 M.Takenaka：“钻石的正电子 2D-ACAR 研究：完美晶粒和缺陷”Mater.Sci

M.Hasegawa, Z.Tang, T.Chiba, M.Saito.A.Kawasuso, T.Akahane, Z.-Q.Li, Y.Kawazoe and S.Yamaguchi: ""Positron 2D-ACAR Study of Divacancies in Si : Experiments and Theory"." Mater.Sci.Forum. 255-257. 414-416 (1997)

M.Hasekawa、Z.Tang、T.Chiba、M.Saito.A.Kawasuso、T.Akahane、Z.-Q.Li、Y.Kawazoe 和 S.Yamaguchi：“Si 中双空位的正电子 2D-ACAR 研究

Z.Tang, M.Hasegawa, T.Chiba, H.Sumiya, Z.Q.Li, T.Akahane, Y.Kawazoe and S.Yamaguchi: ""Positron 2D-ACAR in Perfect Crystals of Diamond, Si and Ge : First-Principles Calculations and Experiments"." Mater.Sci.Forum. 255-257. 411-413 (1997)

Z.Tang、M.Hasekawa、T.Chiba、H.Sumiya、Z.Q.Li、T.Akahane、Y.Kawazoe 和 S.Yamaguchi：“金刚石、Si 和 Ge 完美晶体中的正电子 2D-ACAR：第一原理

Z.Tang, M.Hasegawa 他: "Electron momentun distributions in elemental semiconductors probed by positrons" Phys.Rev.B. 57・19. 印刷準備中 (1998)

Z.Tang、M.Hasekawa 等：“正电子探测元素半导体中的电子动量分布”Phys.Rev.B. 准备印刷（1998 年）

M.Tabata, M.Hasegwa他: "Positron annihilation and ESR studies of electron- or neutron-irradiated silica glass" J.Nucl.Mat.239. 228-235 (1996)

M.Tabata、M.Hasegwa 等人：“电子或中子辐照石英玻璃的正电子湮没和 ESR 研究”J.Nucl.Mat.239 (1996)。