Study on spin device characteristic having p-n-p structure using GeTe based ferromagnetic semiconductors

使用GeTe基铁磁半导体的p-n-p结构自旋器件特性研究

基本信息

批准号：
18560306
负责人：
ASADA Hironori
金额：
$ 2.44万
依托单位：
Yamaguchi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

We have studied on the growth of GeTe based ferromagnetic semiconductors by molecular-beam epitaxy (MBE) method and fabrication of ferromagnetic tunnel junction (MTJ), and obtained the following results.1. It was found that the crystallinity and magnetic properties of GeTe based ferromagnetic semiconductors strongly depended on Te/magnetic ion flux ratio. It was confirmed that crystallinity of the film on a SrF_2 substrate was better than that on a BaF_2 substrate. The obtained Curie temperatures were 200 K for Ge_<1-x>Mn_XTe with x=008 and 190 K for Ge_<1-x>Cr_XTe with x=0.07, respectively.2. MTJs having p-n-p structure using n-type semiconductor CdS barrier were grown by ICB method and the tunnel current was observed for MTJ with CdS barrier thickness of 3.4 nm. The estimated barrier height using Simmons equation was 0.28 eV which was quite small compared to the designed value (2.1 eV). However, tunnel magnetoresistance was not obtained. MTJs were also grown by MBE and successfully obtained GeTe/GeMnTe/CdS/GeMnTe epitaxial films.3. MTJs with barrier layer of p-type semiconductor ZnTe, ferromagnetic insulator EuS and SrF_2 were fabricated. Epitaxial growth on a BaF2 substrate by using MBE method was confirmed in both multilayers with ZnTe and EuS barrier layers. Magnetoresistance ratio of 4.2 % at 10 K was obtained in the GeTe/GeMnTe/EuS(2 nm)/GeTe structure. The estimated barrier thickness from I-V characteristics using Simmons equation agreed well with the designed value and the barrier heights were 0.88-1.07 eV.

我们已经研究了通过分子束外延（MBE）方法和铁磁性隧道连接（MTJ）的制造基于Gete的铁磁半导体的生长，并获得了以下结果。1。已经发现，基于Gete的铁磁半导体的结晶度和磁性极大地取决于TE/磁离子通量比。已经证实，在SRF_2底物上胶片的结晶度要比BAF_2底物上的结晶性更好。对于X = 008和190 K的GE_ <1-X> ge_ <1-x> cr_xte，获得的curie温度分别为x = 008和190 k的200 k，分别为x = 0.07 .2。使用N型半导体CD屏障具有P-N-P结构的MTJ通过ICB方法生长，并且观察到MTJ的MTJ隧道电流，CDS屏障厚度为3.4 nm。使用Simmons方程的估计屏障高度为0.28 eV，与设计值（2.1 eV）相比非常小。然而，未获得隧道磁路。 MBE还种植了MTJ，并成功获得了Gete/gemnte/cds/gemnte外延电影。3。制造了具有P型半导体ZnTE，铁磁绝缘子EUS和SRF_2的MTJ。在具有ZnTE和EUS屏障层的多层人士中，使用MBE方法在BAF2底物上的外延生长均得到证实。在Gete/Gemnte/eus（2 nm）/Gete结构中，在10 K时获得了4.2％的磁性比率。使用Simmons方程与设计值非常吻合，屏障高度为0.88-1.07 eV的I-V特性的估计屏障厚度。