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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（BEEM/BEES）研究半导体/磁性材料纳米结构中自旋相关的电子隧穿。主要研究结果如下：1.我们研制了低温BEEM/BEES测量系统，使从样品制备到LT-MEEM/BEES测量的整个过程都可以在真空中进行; 2.新型表面半导体/磁性材料纳米结构的制备：（1）我们研究了Fe在GaAs（001）表面的沉积，并发现4x 6重建表面给出最可靠的Shoonet接触。(2)In为了阐明MnAs和CrAs在锌层结构中结晶的性质，基于第一性原理计算，提出了亚单层MnAs覆盖GaAs（001）的表面结构模型。 ...更多信息 LEED IV分析。(3)In为了制备与铁硅化物相关的半导体/磁性材料表面纳米结构，研究了铁在Si表面的沉积。3<3><3>.对不同Fe层厚度的GaAs（001）/Fe肖特基接触的BEES观察表明，Fe层中的电子衰减长度随电子能量的变化范围为1.52 ~ 2.74 nm，4.通过RHEED摇摆曲线和LEED IV分析对GaAs（001）c（4 × 4）表面的仔细检查表明，GaAs（001）c（4 × 4）不是单一结构，并且具有至少两个相似但不同的结构。实验结果还表明，即使在300℃的衬底温度下，它们之间也会发生相变。基于c（4x 4）表面的多结构性质，可以很好地解释低温MBE生长在GaAs（001）c（4x 4）表面上的混乱行为。少