Thin Film Diluted Magnetic Semiconductors with Tetradymite Structure

具有辉辉石结构的薄膜稀磁半导体

• 批准号: 0305221
• 负责人: Ctirad Uher
• 金额: $ 38.34万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0305221&HistoricalAwards=false
• 关键词: Thin; Film; Diluted; Magnetic; Semiconductors

This project explores the simultaneous presence of electronic and spin degrees of freedom in the tetradymite-type A2V B3VI (A=Bi, Sb; B=Te, Se) family of semiconductors. The incorporation of relatively high concentrations of magnetic impurities in tetradymite-type semiconductors, and thus higher Curie temperatures, is sought through thin films of these materials. The project focuses on several objectives: 1) to demonstrate the growth of thin films of Sb2Te3, Bi2Te3, and Bi2Se3 -as well as alloys and superlattices of these binary compounds-doped with transition metals; 2) to explore the upper limits of incorporation of the magnetic impurities (phase diagram) in these hosts; and 3) pursue a comprehensive program of characterization of the structural, magnetic, and transport properties of the obtained DMS (dilute magnetic semiconductor) films. The role of the magnetic impurities in the tetradymite semiconductors and their impact on properties will be studied employing electrical conductivity, magnetoresistance, thermopower, thermal conductivity, specific heat, Hall effect, magnetization, and magnetic susceptibility measurements from temperatures of 2K to 300K and in magnetic fields of 0 to 9 T. The project is expected to advance basic knowledge of diluted magnetic semiconductors and thereby help lay groundwork for future spintronics applications. Since the crystal structure and the magnetic ions utilized in the proposed materials are distinctly different from traditional diluted magnetic semiconductors such as Mn-doped III-V or II-VI compounds, the project may shed new light on fundamental issues of magnetism in semiconductors, and possibly of magnetism generally. The highly anisotropic environment of the tetradymite-type crystal structure with its pronounced octahedral coordination of atoms may play a key role in the development of magnetic order; this is in contrast to the cubic environment of Mn-doped zinc-blende or wurtzite structures with their distinct tetrahedral bonding.%%% This project addresses basic materials and condensed matter physics research issues in a topical area of materials science with technological relevance, and places emphasis on the integration of research and education. Graduate and undergraduate students will be involved in the synthesis, processing, and characterization of electronic/magnetic materials. Training of graduate and undergraduate students in the areas of MBE growth, semiconductor physics, and magnetism provides special opportunities for them in research and education, and a sound investment in the future workforce. The project is jointly supported by the DMR Electronic Materials and Condensed Matter Physics programs.***

该项目探索碲辉石型 A2V B3VI（A=Bi、Sb；B=Te、Se）半导体系列中同时存在的电子和自旋自由度。通过这些材料的薄膜寻求在辉辉石型半导体中掺入相对高浓度的磁性杂质，从而获得更高的居里温度。该项目重点关注以下几个目标：1) 展示 Sb2Te3、Bi2Te3 和 Bi2Se3 薄膜以及这些掺杂过渡金属的二元化合物的合金和超晶格的生长； 2）探索这些主体中磁性杂质（相图）掺入的上限； 3) 对所获得的 DMS（稀磁半导体）薄膜的结构、磁性和传输特性进行全面的表征。将通过在 2K 至 300K 温度和磁性条件下的电导率、磁阻、热电势、导热率、比热、霍尔效应、磁化强度和磁化率测量来研究辉辉石半导体中磁性杂质的作用及其对性能的影响。该项目预计将推进稀磁半导体的基础知识，从而帮助为未来的自旋电子学应用奠定基础。由于所提出的材料中使用的晶体结构和磁性离子与传统的稀释磁性半导体（例如掺杂锰的 III-V 或 II-VI 化合物）明显不同，因此该项目可能为半导体磁性的基本问题提供新的线索，并且一般可能是磁性的。碲辉石型晶体结构的高度各向异性环境及其明显的原子八面体配位可能在磁序的发展中发挥关键作用；这与具有独特四面体键合的锰掺杂闪锌矿或纤锌矿结构的立方环境形成鲜明对比。%%% 该项目解决了具有技术相关性的材料科学主题领域的基础材料和凝聚态物理研究问题，以及注重研究与教育的结合。研究生和本科生将参与电子/磁性材料的合成、加工和表征。 MBE 增长、半导体物理和磁性领域的研究生和本科生培训为他们提供了特殊的研究和教育机会，并为未来的劳动力提供了良好的投资。该项目由 DMR 电子材料和凝聚态物理项目联合支持。***