III-V族半导体半金属异质结外延结构的自旋注入研究

项目名称： III-V族半导体半金属异质结外延结构的自旋注入研究

项目编号： No.11204295

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 物理学I

项目作者： 刘奇

作者单位： 中国科学院半导体研究所

项目金额： 30万元

中文摘要： 以Heusler合金为代表的半金属材料具有费米面附近自旋极化率高（近100%）、居里温度高于室温、易于同半导体产业集成等优点，被认为在研制新型自旋电子器件方面具有重大价值。然而报道的实验中自旋注入极化率并没有理论预期高（最高约60%,Co2FeSi，2K），一般归因为界面缺陷、扩散和成键等结构因素。此外，界面原子间的轨道混合不仅会造成界面两侧的电荷转移，也会导致界面附近态密度产生不同于两侧体材料的自旋极化。我们初步计算表明半导体方向上存在着厚约若干原子层的界面，该结构对注入电子的自旋极化率可能有决定性的影响。我们拟采用光激发隧穿电容谱探测半金属能带结构，应用极化电荧光谱探测异质结中自旋注入极化率，同时使用第一性原理方法对于界面电子结构色散关系进行计算，通过改进样品组分和结构等方式，探索界面对于半金属/半导体结构自旋输运过程的影响，为半金属/半导体在新型半导体自旋电子器件方面的应用打下基础。

中文关键词： 自旋极化；自旋注入；半金属；异质结；界面

英文摘要： Half-metals such as the Heusler alloy have the following superiorities: near 100% spin polarization at Fermi level, Cuire temperature over the room temperature and easy to integrate in modern industry of semiconductors, thus are believed to have greate potential for the research of new spintronic devices. However, data from published reports shows much lower polarizations than expected (the highest about 60%, Co2FeSi, 2K). The reason was generally attributed to the defects, interactions and difussions which happen near the interface. Besides, the interfacial atomic obrit intermixing will not only cause the charge transfer between the two sides of semiconductor and the half-meal, but also result in different spin polariztion of the Density of States (DOS) near interface with those in both bulk. Our calcualtion show that there exists an interface structure of several atomic layers, and it is such structure that may play an important role in the spin polarization. We are planning to use the method of polarized electroluminescence to detect the injected electronic spin polarization and use the photo-excited capacitance-sensitive resonant tunneling spectroscopy to obtain the band structure of half-metal. Besides, first principle based calculation will also be used to analyse the interfacial electronic structures and

英文关键词： Spin Ploarized；Spin Injecetion；Half-Metal；Heterojunction；Interface