| Co-Investigator(Kenkyū-buntansha) |
ASANO Tanemasa Tokyo Institute of Technology, Graduate School of Science & Engineering,Research, 大学院総合理工学研究科, 助手 (50126306)
ISHIWARA Hiroshi Tokyo Institute of Technology, Graduate school of Science & Enginerrirng,Associa, 大学院総合理工学研究科, 助教授 (60016657)
KOMA Atsushi Univertisy of Tokyo, Faculty of Science , Professor, 理学部, 教授 (00010950)
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| Research Abstract |
This project aims to investigate electronic properties of nearly lattice- matched' heterostructures and to habrication of low-power, very- high-speed electron devices. The structures are composed of semiconductor films such as Si-, Ge and GaAs, and insulator films such as CaF_2 SrF_2 and BeF_2. The lattice constants of these alkaline earth fluorides can be continuously adjusted from 5.46<Ang> of CaF_2 to 6.20<Ang> of BaF_2 by forming mixed crystals. In the experiments, fluoride films were grown on Si substrates using molecular beam epitaxy. Then, semiconductor overlayers of SI, Ge, or GaAs were grwn in the same vacuum. Ir order to improve the crystalline quality of the top semiconductor films, new heteroepitaxial techniques were proposed; that is, the predeposition technique for the growth of Si film in which a thin amorphous Si layer was deposited on the fluoride surface prior to the growth of a thick Si films at elevated temperature, and the electron beam exposure epitaxy for the growht og Ge and GaAs, in which the fluoride surface was modified by e-beam exposure prior to the growth of G or GaAs. The structural and elctrical properties of the films thus fabricated were excellent. Actually, Si-MOSFETs and GaAs-MESFETs were fabricated in these films. Fabrication of Ge and GaAs-MESFETs were also tried using the fluoride gate insulators. The enhancement-type operation of GaAs mISFETs was achieved, which suggests usefulness of the fluoride materials for the electron device applications.
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