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Fabrication and Study of Nanostructure Diluted Magnetic Semiconductors

纳米结构稀磁半导体的制备与研究

基本信息

批准号：
08555001
负责人：
OKA Yasuo
金额：
$ 6.98万
依托单位：
Research Institute for Scientific Measurements, Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

The objective of this research project is to fabricate new nanostructure lattices composed of diluted magnetic semiconductors (DMSs) and also to study magneto-optical properties of the nanostructures. For this purposes, we have fabricated 2-dimensional quantum wells, 1-dimensional quantum wires, and 0-dimensional quantum dots by molecular beam epitaxy, atomic beam epitaxy, and electron-beam lithography techniques. Materials we have fabricated are Cd_<1-x>Mn_xTe and Cd_<1-x>Mn_xSe with Mn concentration of x= 0.03-0.3.Obtained these nanostructures have been studied by the ultrafast laser spectroscopy using femto-second pulse lasers. Time resolved photoluminescence has been measured in Cd_<1-x>Mn_xTe quantum wells by the selective excitation of the quantum-well exciton states. The transient behavior of the exciton luminescence clearly shows the formation process of the excitonic magnetic polarons, which is suppressed by the strong external magnetic fields. Quantum dots of Cd_<1-x>Mn_xSe grown by the Stranski-Krastanow mode on ZnSe buffer layers show very fast decay of the excitons in the dots. The lifetime of the quantum dot excitons is markedly increased by the external magnetic fields. The phenomena are interpreted by decrease of the nonradiative process due to the shrinkage of the exciton wavefunction by the magnetic field. Pump-probe transient absorption spectroscopy has been made on Cd_<1-x>Mn_xTe quantum well, The exciton and magnetic polaron dynamics are observed in the 2 ps to 3 ns time region. Quantum wires of Zn_<1-x>Cd_xSe system show the photoluminescence evidence of the 1-dimensional confinement effect as well as the relaxation of the lattice strains by decreasing the wire width. Fabrication of Cd_<1-x>Mn_xSe quantum wires is under progress.The remarkable magneto-optical effects of the nanaostructure DMSs elucidated in the present project will stimulate the research of the new magneto-optical microdevices.

该研究项目的目的是制造由稀释磁性半导体（DMS）组成的新纳米结构晶格，并研究纳米结构的磁光特性。为此，我们通过分子束外延、原子束外延和电子束光刻技术制备了二维量子阱、一维量子线和0维量子点。我们制备的材料是Cd_<1-x>Mn_xTe和Cd_<1-x>Mn_xSe，Mn浓度为x= 0.03-0.3。通过使用飞秒脉冲激光器的超快激光光谱研究了这些纳米结构。通过量子阱激子态的选择性激发，在Cd_<1-x>Mn_xTe量子阱中测量了时间分辨光致发光。激子发光的瞬态行为清楚地显示了激子磁极化子的形成过程，该激子磁极化子受到强外部磁场的抑制。通过Stranski-Krastanow模式在ZnSe缓冲层上生长的Cd_<1-x>Mn_xSe量子点显示出点中激子的非常快的衰减。外部磁场显着增加了量子点激子的寿命。该现象可以解释为由于磁场收缩激子波函数而导致非辐射过程减少。在Cd_<1-x>Mn_xTe量子阱上进行了泵浦-探针瞬态吸收光谱分析，在2 ps到3 ns时间段观察到了激子和磁极化子动力学。 Zn_<1-x>Cd_xSe体系的量子线显示出一维限制效应的光致发光证据以及通过减小线宽度来松弛晶格应变。 Cd_<1-x>Mn_xSe量子线的制备正在进行中。本项目阐明的纳米结构DMS的显着磁光效应将刺激新型磁光微器件的研究。