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Study of injection of spin - polarized electrons into semiconductors through ferromagnetic metal

自旋极化电子通过铁磁金属注入半导体的研究

基本信息

批准号：
11450023
负责人：
KAWAGUCHI Hitoshi
金额：
$ 9.47万
依托单位：
Yamagata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

We investigated mainly the following four topics to create new nonlinear optical functional devices based on the pitchfork bifurcation bistable operation of vertical-cavity surface-emitting lasers (VCSELs) and injection of spin-polarized electrons.(1) We studied the bistable switching between the two orthogonal polarization mode existing in the VCSEL with a squared shape waveguide. The relative magnitude of self- and cross-saturation coefficients are crucial to determine the characteristics of polarization switching of laser diodes. The numerical calculation confirmed that the relation between self- and cross saturation coefficients satisfies the condition for polarization bistability in both balk and quantum well active layers. The bistable conduction is satisfied in the wider region for a compressively strained quantum well, especially in the region with large linear gains.(2) All-optical signal processing, such as demultiplexing with a signal bit width conversion function and the conversion between RZ and NRZ formats, were experimentally demonstrated using a polarization bistable VCSEL. We have shown by our simulations that the 3R function (Retiming, Reshaping, and Regenerating) can be obtained using a such VCSEL.(3) We estimated the spin relaxation time of the electrons drifting through the p-n junction from the time- and polarization- resolved photoluminescence. The result showed that the polarization fairly maintained during the drift.(4) We fabricated the light emitting diode (LED) with an n-side electrode made of ferromagnetic metal, CoCr. However, the light output from LED was unpolarized. This result points out that the polarized electrons may be de-polarized at the interface between GaAs and CoCr.

本论文主要研究了以下四个方面的内容，即基于垂直腔面发射激光器（VCSEL）的音叉分叉和自旋极化电子注入的非线性光学功能器件。(1)本文研究了方形波导VCSEL中两个正交偏振模之间的偏振态转换。自饱和系数和交叉饱和系数的相对大小是决定半导体激光器偏振开关特性的关键。数值计算证实了自饱和系数和交叉饱和系数之间的关系满足量子阱和量子阱有源层中的偏振双稳条件。对于压缩应变量子阱，在较宽的区域内，特别是在具有大线性增益的区域内，均满足双折射导电。(2)利用偏振模色散VCSEL进行了全光信号处理的实验研究，如信号位宽转换功能的解复用以及RZ和NRZ格式之间的转换。我们已经通过我们的模拟表明，可以使用这样的VCSEL获得3R功能（重定时、整形和再生）。(3)我们从时间分辨和偏振分辨的光致发光中估算了漂移通过p-n结的电子的自旋弛豫时间。结果表明，在漂移过程中，偏振态得到了较好的保持。(4)我们制作的发光二极管（LED）的n侧电极由铁磁金属，钴铬。然而，从LED输出的光是非偏振的。这一结果指出，极化电子可能是退极化GaAs和CoCr之间的界面。