| Co-Investigator(Kenkyū-buntansha) |
HIRAKAWA Kazuhiko Institute of Industrial Science, University of Tokyo, Professor, 生産技術研究所, 助教授 (10183097)
FUJIMORI Atsushi Graduate School for Frontier Sciences, University of Tokyo, Professor, 大学院・理学系研究科, 教授 (10209108)
TAKITA Koki Institute of Materials Science, University of Tsukuba, Professor, 物質工学系, 教授 (00011213)
ANDO Koji Materials Science Division, Electotechnical Laboratory, Senior Researcher, 材料科学部所, 主任研究官
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| Research Abstract |
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
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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
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