权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Dynamical Processes of Electron-Spin Systems Photo-Excited in Semiconductor Quantum Dots

半导体量子点光激发电子自旋系统的动力学过程

基本信息

批准号：
14204030
负责人：
ITOH Tadashi
金额：
$ 35.78万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

The purpose of this project is (1) to know the singlet-triplet spin conversion of quantum-confined excitons and the relaxation dynamics of confined exciton magnetic polarons in non-magnetic and magnetic semiconductors and (2) also to approach to new kinds of phenomena inherent to confined exciton-spin complex systems. The materials are CuCl semiconductor quantum dots and mixed crystals of CdMnTe semi-magnetic semiconductor. In the latter system, excions are confined in alloy potential wells, that is, naturally grown quantum dots.1. Confined excitons inCuCl quantum dots : (1) In the magneto-luminescence spectra at 4K, it has been found that the intensity enhancement and the spectral modification of the localized exciton luminescence occur both under Faraday and Voigt geometries. These results clearly show that, due to the exciton confinement, the optical transition to/from the spin-triplet state (dark exciton state) is partially allowed and the mixing occurs between the longitudinal and … More transverse excitons. (2) By means of two-photon resonance excitation into biexciton states, there has been found the stable J=2 state which corresponds to the spin-triplet state of biexciton. Furthermore, the J=0 biexciton shows very efficient lasing which comes from the superradiant nature of the biexciton. (3) The measurement of temporal behavior and temperature dependence of the magneto-luminescence and absorption may clarify the role and the dynamics of spin-triplet excitons confined in their translational motion.2. Locally confined excitons in CdMnTe : (1) Under the intense, selective excitation of locally confined excitons in alloy potential wells, there has been found a new nonlinear luminescence band which shows giant magneto-optical effects and ultra-fast decay. The luminescence and their spin memory may be related with a certain many-body effect of localized exciton magnetic polarons. (2) It is necessary to clarify the ultra-fast relaxation processes of the correlated electron-spin systems through the measurement of transient absorption and their magnetic field dependence. Less

本项目的目的是：(1)了解非磁性和磁性半导体中量子受限激子的单重态-三重态自旋转换和受限激子磁极化子的弛豫动力学；(2)探索受限激子-自旋复合系统固有的新现象。材料为CuCl半导体量子点和CdMnTe半磁性半导体混合晶体。在后一种体系中，激子被限制在合金势阱中，即自然生长的量子点中。约束激子incl量子点：(1)在4K磁致发光光谱中，发现局域激子发光在法拉第和Voigt几何下都发生了强度增强和光谱修饰。这些结果清楚地表明，由于激子约束，从自旋三重态（暗激子态）的光学跃迁是部分允许的，并且在纵向激子和更多的横向激子之间发生混合。(2)通过双光子共振激发双激子态，发现了与双激子自旋三重态对应的稳定J=2态。此外，由于双激子的超辐射特性，J=0双激子显示出非常有效的激光。(3)测量磁致发光和磁吸收的时间行为和温度依赖关系，可以阐明限制在其平动运动中的自旋三重态激子的作用和动力学。CdMnTe中的局域约束激子：(1)在合金势阱中局域约束激子的强烈、选择性激发下，发现了一个具有巨磁光效应和超快衰减的非线性发光带。发光及其自旋记忆可能与局域激子磁极化子的多体效应有关。(2)有必要通过测量瞬态吸收及其磁场依赖性来阐明相关电子-自旋系统的超快速弛豫过程。少