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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.

基于垂直腔面发射激光器（VCSELs）的干草叉分岔双稳态工作和自旋极化电子注入，我们主要研究了以下四个主题，以创建新的非线性光学功能器件。(1)利用方形波导研究了VCSEL中存在的两种正交偏振模式的双稳态切换。自饱和系数和交叉饱和系数的相对大小是决定激光二极管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巴尔克和量子阱有源层极化双稳定的条件。压缩应变量子阱在较宽的区域内，特别是在线性增益较大的区域内，可以满足双稳传导。(2)利用偏振双稳态VCSEL实验验证了全光信号处理，如信号位宽转换函数的解复用以及RZ和NRZ格式之间的转换。我们已经通过仿真证明，使用这样的VCSEL可以获得3R函数（重新计时，重塑和再生）。(3)利用时间分辨光致发光和偏振分辨光致发光，估计了电子在p-n结中漂移的自旋弛豫时间。结果表明，在漂移过程中，极化基本保持不变。(4)采用铁磁金属CoCr制备了n侧电极发光二极管（LED）。然而，LED的光输出是非偏振的。这一结果表明，在GaAs和CoCr的界面处，极化电子可能会去极化。