| Project/Area Number |
12650307
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Gifu University |
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Principal Investigator |
SHIMAKAWA Koichi Faculty of Engineering, Gifu University, Professor, 工学部, 教授 (60021614)
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| Co-Investigator(Kenkyū-buntansha) |
GANJOO Ashtosh Faculty of Engineering, Gifu University, Research Associate, 工学部, 助手 (00262965)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2001: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2000: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Keywords | Defect spectroscopy / Amorphous silicon / chalcogenide glasses / photoinduced effect / Photoconduction / ac transport / アモルファス半導体 / 光ルミネッセンス / 雑音 / 光生成欠陥 / 光構造変化 / 欠陥スピクトロスコピー |
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| Research Abstract |
In the present study, we proposed that a new defect spectroscopy could be established from optical and electrical noise measurements. The term "defect spectroscopy" is evaluation of density and energy levels of defect states in semiconductors (amorphous semiconductors).
As a macroscopic inhomogeneity originating from potential fluctuations is expected to dominate photoconductivity, we focused the noise measurements on photocurrent bith for hydrogenated amorphous silicon (a-Si : H) and amorphous chalcogenides (a-Ch). The results we obtained are summarized below :
1. In a-Si : H, long-range potential fluctuations dominate "noise (current fluctuations)" and hence these effects mask the effect of defects. It is hard to deduce information of defects from noise measurement itself. Thus we measured AC photoconductivity (photoconductivity under ac electric field) which is one of current noises. From this measurement we got remarkable results which produce the extent of potential fluctuations (en
… More
ergy and space). This has been reported in 19^<th> Int. Conf on Amorphous and Microcrystalline Seminconductors (Nice, France, August 2001) as an invited talk.
2. In a-Ch, photoirradiation induces various photostructural changes and defect creations and hence the situation is more complex than that for a-Si : H. Therefore, we first focused to study the dynamics of photostructural changes. We found the "transient photostructural changes" for the first time. These were published in Physical Review (rapid communication) and in print (2002).
3. In a-Ch, defects are induced by prolonged photoirradiation and current noises are dominated by defects after prolonged photoirradiation (metastable state). We showed in 19^<th> Int. Conf on Amorphous and Microcrystalline Seminconductors (Nice, France, August 2001) that the ac photocurrent method can be useful as a new "defect spectroscopy".
4. Frequency-resoloved photoconductivity measurement can be useful technique, in which real and imaginary parts of photo-response will be decomposed. Through this technique, life-time distribution of photocarriers can be obtained. These should be compared with the life-time distribution of photoliminescence. These works will be continued. Less
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