| Project/Area Number |
12450137
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
電子デバイス・機器工学
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| Research Institution | University of Tsukuba |
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Principal Investigator |
HASEGAWA Fumio University of Tsukuba, Univ.of tsukuba, Inst.of Applied Physics, Professor (70143170)
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| Co-Investigator(Kenkyū-buntansha) |
SUEMASU Takashi Univ.of Tsukuba, Inst.of Applied Physics, Associate Professor (40282339)
CHICHIBU Shigefusa Univ.of Tsukuba, Inst.of Applied Physics, Associate Professor (80266907)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥9,700,000 (Direct Cost: ¥9,700,000)
Fiscal Year 2002: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2001: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2000: ¥4,600,000 (Direct Cost: ¥4,600,000)
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| Keywords | solar battery / silicide / beta-FeSi2 / BaSi_2 / MBE growth / control of conduction type / energy band structure / エネルギーバンド構造 / 多層膜法 / 同時蒸着法 / 移動度 / 鉄シリサイド |
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| Research Abstract |
Solar batteries are usually made of amorphous Si or poly-Si, but the conversion efficiency is limited. One of the reason is low absorption coefficient of Si. CuInSe2/CdS can give a higher efficiency by a deposited poly-crystalline, but it contains toxic Se and Cd. The purpose of this project is to investigate an environmentally friendly semiconductor with high absorption coefficient, therefore, high efficiency with a thin film.
One of the candidate was a semiconducting silicide ; beta-FeSi_2, but there had been no report on a high quality thin film and details of the band structure had not also been clear. We succeeded to grow a high quality beta-FeSi_2 film by multi-layer method and MBE growth, which could give a higher carrier mobility of one order of magnitude than those reported so far. The absorption coefficient was proved to be as high as 10^5/cm. Energy band structure was also made clear: indirect band gap of 0.81eV and direct band gap of 0.97eV. It was found that conduction type was controlled by the depositing Si/Fe ratio.
Band gap of 0.81eV is, however, too small to give a high efficiency as a solar battery by itself. Therefore, another semiconducting silicide with a wider band gap was searched. BaSi_2 was another candidate because it was reported that the band gap was either 1.3eV or 0.7eV. Firstly, we investigated poly-crystalline BaSi_2 and found it has an indirect band gap of 1.1eV and direct band gap of 1.25eV, a little bit wider than beta-FeSi_2. We tried to grow BaSi_2 thin film on Si (111) by a MBE method and succeeded to get a high quality thin film for the first time.
Solar battery characteristics has not been clarified yet, but these results could indicate that semiconducting silicide is a good candidate of environmentally friendly solar battery materials.
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