Study on magneto-transport properties of semiconductor/magnetic-material heterostructures by ballistic electron emission microscopy

弹道电子发射显微镜研究半导体/磁性材料异质结构的磁输运特性

基本信息

批准号：
13450009
负责人：
YOSHINO Junji
金额：
$ 8.13万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

The aim of this study is to explore the spin-dependent electron tunneling in semiconductor/magnetic-material nano-structures by using ballistic electron emission microscopy and spectroscopy (BEEM/BEES). The major results obtained are as follows.1.We have developed low temperature BEEM/BEES measurement systems, which make it possible that the whole the measurement procedures from sample preparation to LT-MEEM/BEES measurements under ultrahigh vacuum.2.On preparation of novel surface semiconductor/magnetic materials nano-structures(1)We have investigated Fe deposition on GaAs(001) surface with various surface reconstructions, and find that 4x6 reconstructed surfaces give most reliable Shottky contact.(2)In order to clarify the properties of MnAs and CrAs crystallized in zincblende structures, which is expected to have half-metallic band structures based on first principle calculation, surface structure model of GaAs(001) covered with sub-monolayer MnAs was presented based on STM observat … More ions and LEED IV analysis.(3)In order to prepare iron silicide related semiconductor/magnetic materials surface nanostructures, Fe deposition on Si surface was investigated. It was found that Ag-terminated Si(111)√<3>x√<3>-Ag surface allow us to prepare Fe_3Si nano-dot having 10-20 nm in diameter.3.BEES observations of GaAs(001)/Fe Schottky contacts with different Fe layer thickness reveal that electron attenuation length in Fe layers is to be ranging from 1.52 to 2.74 nm depending on electron energy, which is fairly longer than previous reports.4.Careful examination of GaAs(001)c(4x4) surfaces by RHEED rocking curve and LEED IV analysis reveals that GaAs(00l)c(4x4) is not single structure, and have at least two similar but different structures. Furthermore it was demonstrated that phase transition between them can be taken place even at substrate temperatures as low as 300℃ and that confusing behaviors of low temperature MBE growth on GaAs(001)c(4x4) surfaces seems to be well accounted base on its multi-structure nature of c(4x4) surfaces. Less

本研究的目的是利用弹道电子发射显微镜和光谱学（BEEM/BEES）探索半导体/磁性材料纳米结构中的自旋相关电子隧道效应。主要结果如下： 1.我们开发了低能电子隧道效应。高温BEEM/BEES测量系统，使得超高真空下从样品制备到LT-MEEM/BEES测量的整个测量过程成为可能。2.新型表面半导体/磁性材料的制备纳米结构(1)我们通过各种表面重构研究了GaAs(001)表面上的Fe沉积，发现4x6重构表面给出了最可靠的肖特基接触。(2)为了阐明闪锌矿中结晶的MnAs和CrAs的性质基于第一性原理计算，预计具有半金属能带结构，基于STM提出了亚单层MnAs覆盖的GaAs(001)表面结构模型观察… 更多离子和LEED IV分析。(3)为了制备硅化铁相关的半导体/磁性材料表面纳米结构，研究了Si表面的Fe沉积，发现Ag封端的Si(111)√<3>x。 √<3>-Ag表面允许我们制备直径为10-20 nm的Fe_3Si纳米点。3.GaAs(001)/Fe肖特基与不同Fe接触的BEES观察层厚度表明，根据电子能量，Fe 层中的电子衰减长度为 1.52 至 2.74 nm，这比以前的报道要长得多。4.通过 RHEED 摇摆曲线仔细检查 GaAs(001)c(4x4) 表面LEED IV分析表明GaAs(00l)c(4x4)不是单一结构，并且至少具有两个相似但不同的结构，并且证明它们之间可以发生相变。即使在低至 300℃ 的衬底温度下，GaAs(001)c(4x4) 表面上的低温 MBE 生长的令人困惑的行为似乎基于其 c(4x4) 表面的多结构性质得到了很好的解释。