| Co-Investigator(Kenkyū-buntansha) |
SOTA Takayuki Waseda University, School of Science and Engineering, Professor, 理工学部, 教授 (90171371)
HAMA Yoshimasa Waseda University, Advanced Research Institute of Science & Engineering, Professor, 理工学総合研究センター, 教授 (40063680)
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| Research Abstract |
Amorphous silica, a key material in the modern high-tech society. Is widely used as an insulating layer for a semiconductor device or as an optical fiber. In the present research, the effects of point defects such as impurities or vacaancies in the silica film on the electrical and optical properties have been systematically studied. The point defects were detected by photoluminescence, ESR, FT-IR, visible-VUV absorption, EPMA and SIMS. Electrical properties are examined by high-field conduction. Dielectric breakdown, and C-V measurement. Knowledge on the presence of oxygen vacancy and the estimation of its concentration, structural stabilization by impurity doping, and the relation between the defect concentration and the synthesis method has been obtained. In 1997, we demonstrated tha clear photoluminescence can be obtained in this amorphous SiOィイD22ィエD2 film by using an intense photon source such as an excimer laser or synchrotron radiation. This indicates that photoluminescence can
… More
be a strong tool to detect point defects in a-SiOィイD22ィエD2. Using this method, point defects in thermal silicon dioxide and SIMOX buried oxide and those induced in these oxides by ion implantation and heat treatment have been detected. The structures of these defects have also been identified. In 1998, researches were extended to fluorine-doped SiOィイD22ィエD2 film, SIMOX oxide, and silicon nitride film, and the structures of point defects in these materials were clarified. The effect of point defects on the dielectric strength was also examined by measuring the breakdown voltage. In 1999, researches were further extended to a-SiNィイD2xィエD2 a-SiOィイD2xィエD2NィイD2yィエD2, and TaィイD22ィエD2OィイD25ィエD2 films, focusing on the effects of ion implantation and heat treatment on the concentration of point defects. Photochemical reactions responsible for the formation of optical fiber grating in Ge-doped silica glass have been also clarified. Furthermore, stable and high-efficient fabrication method of optical fiber grating by use of ion implantation has bee proposed. Less
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