Optical Properties of Spin Controlled Semiconductor Nanostructures

为了突破传统的基于电荷利用的半导体工程设计理念，我们的研究目标是寻找自旋控制器件中半导体纳米结构中电子自旋自由度的基本规律并培养其控制技术。基于光谱学方法，系统地了解光子角动量与导电电子和定域电子自旋之间的关系是实现新型自旋控制光功能器件的必要条件。研究结果总结如下：1。在体稀磁性半导体中发现了稳定的激子磁极化子。用瞬态光谱法研究了极化子的形成机理和弛豫动力学。利用光致发光和瞬态光谱测量方法，研究了非对称双鲁特磁性半导体量子阱中的非对称激子磁极化子态。（Takeyama et al.）利用分子束外延技术成功地合成了CdTe、MnTe和（Cd, Mn） Te的纳米级、高质量的自组织量子点。本文报道了CdTe点的室温激子观测，Mn跃迁的发射寿命异常缩短，（Cd, Mn） Te点的磁极化子效应增强。（Kuroda, Takita et al.）采用离子注入技术合成了新型的含Cr或Ni的II-V型稀磁性半导体合金。（Ga, Cr） As合金是一种新型的III-V型稀磁半导体。磁圆二色光谱研究了p-d交换和巨塞曼效应。在砷化镓衬底上构建双层（Cd, Mn）Te结构，设计了光波导结构。（Ando et al.）利用簇模型研究了磁性半导体（Ga, Mn） As的电子结构。阐明了导电载流子的起源以及载流子自旋与Mn自旋之间的耦合，为阐明这些材料的铁磁性和巨磁阻机制提供了必要的基础信息。（Fujimori等人）对（Ga, Mn） As的远红外光导率进行了测量。在费米表面附近发现了一个窄跳型导电带，并提出了该材料中铁磁性的来源与窄跳型导电带的关系。(Hirakawa et al.

Attempting to realize a breakthrough in the conventional devise concept of semiconductor engineering based on utilization of electrical charge, we set our aim of the study as to find the basic law and to cultivate its techniques of controlling spin degree of freedom in the electron of semiconductor nano-stuructures for spin controlled devices. Based on spectroscopic methods, systematic understanding of the relationship between the angular momentum of photons and the spins of conductive electrons and localized electrons are necessary for realization of the new spin controlled opto-functional devices. Thu summary of the research results are :1. It has been found that stable exciton magnetic polarons are formed in bulk dilute magnetic semiconductors. Polaron formation mechanism and relaxation dynamics have been clarified by the transient spectroscopy. Asymmetric exciton magnetic polaron states have been studied by photoluminescence and transient spectroscopic measurements in asymmetric di … More lute magnetic semiconductor quantum well. (Takeyama et al.)2. Self-organized quantum dot of CdTe, MnTe, and (Cd, Mn) Te with nano-size and good quality have been successfully synthesized by molecular beam epitaxy. Room temperature exciton observation in CdTe dots, anomalous shortening of emission life-time of intra Mn transition, enhancement of magnetic polaron effects in (Cd, Mn) Te dots have been reported. (Kuroda, Takita et al.)3. New type of II-V dilute magnetic semiconductor alloys with Cr or Ni has been synthesized by ion implantation techniques. (Ga, Cr) As alloys have been successfully synthesized as a new III-V dilute magnetic semiconductor by mplecular beam epitaxy. Magnetic circular dichroism spectroscopy was used to investigate p-d exchange and giant Zeeman effect. Also optical waveguide structures have been devised by constructing a double layer (Cd, Mn)Te structure on GaAs substrates. (Ando et al.)4. The electronic structure of magnetic semiconductor (Ga, Mn) As has been investigated by a photoemission spectroscopy with a help of cluster model. The origin of the conducting carriers and the coupling between the carrier spin and the Mn spin, which constitutes the basic information necessary to elucidate the mechanism of the ferromagnetism and the giant magneto-resistance observed in these materials, has been clarified. (Fujimori et al.)5. Far-infrared photoconductivity measurement on (Ga, Mn) As has been performed. A narrow hopping type conducting band near the Fermi surface has been found and also the correlation of the narrow band with the origin of ferromagnetism in this material has been suggested. (Hirakawa et al.) Less