Fabrication of Spin Controlled Semiconductor Superstructures

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The group was organized to fabricate new superstructures of III-V and II-Vl diluted magnetic semiconductors and silicon system involving magnetic ions and to study the quantum magneto-optical properties, chemical-species dependence, magnetism and transport properties, spin dynamics and also to establish their basic theories. For these purposes, designing and fabrication of various semiconductor superstructures were made and explored the new magnetism and magneto-optical functionarities. Theoretical investigation of these new properties was also carried out.1. Fabrication and magneto-optical study of quantum nanostructures of diluted magnetic semiconductors New quantum nanostructures of diluted magnetic semiconductors CdMnTe and CdMnSe were fabricated and their magneto-optical properties and applications were studied. The magneto-optical effects and the spin dynamics of electrons and excitons were studied in these quantum wells, wires, and dots by the ultrafast time resolved photolumine … More scence spectroscopy and the pump-and probe transient absorption spectroscopy. New magneto-optical properties were found such as the exciton tunneling in double diluted magnetic quantum wells, the magnetic suppression of the non-radiative process of excitons in the quantum dots and the ultrafast spin relaxation processes of excitons.2.Carrier concentration dependence and chemical trend of electronic and magnetic properties on III-V diluted magnetic semiconductors Carrier concentration control of (Ga, Mn)As was investigated by incorporation of donor and acceptor. Sn-donors were introduced to (Ga, Mu)As up to 5% and the n-type doping demonstrated the possibility of the control of the hole concentration of (Ga, Mn)As3.Growth and properties of silicon-related superstructures doped heavily with magnetic impurities Si-based diluted magnetic semiconductors were fabricated by laser ablation and photo-excited CVD methods. Si films with high concentration of Mn were obtained. A first principle calculation was performed-to indicate that the ferromagnetism similar to that in (Ga, Mn)As is possible in Si : Mn systems.4. Hybrid superstructures based on diluted magnetic III-V semiconductors The carrier induced magnetism with a light irradiation on the (In, Mn)As/(Ga, Al)Sb heterostructures was studied. The results demonstrated the importance of interplay between non-magnetic and magnetic semiconductor layers. Preparation of III-V diluted magnetic semiconductors with Fe ions was also develnned Less