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

该项目的目的是（1）了解量子限制的激子的单三个旋转转换以及在非磁性和磁性半导体中受到约束激子磁极的放松动力学，以及（2）也可以使用新型现象的方法，该现象继承为受限制的激素蜘蛛蛋白复合物复合系统。材料是CUCL半导体量子点和CDMNTE半磁性半导体的混合晶体。在后一种系统中，限制在合金势井中的探索，即自然生长的量子点1。限制的激子Incucl量子点：（1）在4K处的磁发光光谱中，已经发现，在Faraday和Voigt几何形状下，强度增强和局部刺激性发光的光谱修饰都发生。这些结果清楚地表明，由于刺激性的限制，允许向旋转三个态状态（深色激子状态）的光学转变，并在纵向和……更多的横向激子之间发生混合。（2）通过对Biexciton状态的两光子共振兴奋，已经发现了稳定的J = 2状态，该状态与Biexciton的自旋三个状态相对应。此外，j = 0 biexciton显示出非常有效的激光，这来自biexciton的超级性质。（3）测量磁性发光和遗憾的临时行为和温度依赖性可能会阐明限制在其翻译运动中的自旋三曲线激子的作用和动力学。2。 CDMNTE中的局部限制激子：（1）在合金势孔中局部限制的激子的强烈，选择性的兴奋下，发现了一个新的非线性发光带，显示出巨大的磁光效应和超快速衰减。发光及其旋转记忆可能与局部兴奋的磁性极性子的一定多体效应有关。（2）有必要通过测量瞬态滥用及其磁场依赖性来阐明相应电子自旋系统的超快速松弛过程。较少的