1999 Fiscal Year Final Research Report Summary
The Study of Light-induced Expansion in Hydrogenated Amorphous Silicon with Photodegradation
| Project/Area Number |
10650304
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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 |
NONOMURA Shuichi Faculty of Engineering, Gifu University, Professor, 工学部, 教授 (80164721)
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| Co-Investigator(Kenkyū-buntansha) |
NITTA Shoji Faculty of Engineering, Gifu University, Professor, 工学部, 教授 (90021584)
ITOH Takashi Faculty of Engineering, Gifu University, Associate Professor, 工学部, 助教授 (00223157)
YOSHIDA Norimitsu Faculty of Engineering, Gifu University, Associate Professor, 工学部, 助教授 (70293545)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Light-induced expansion / Hydrogenated amorphous silicon / Photodegradation / Laser optical-lever bending method / Amorphous lattice relaxzation / Initial stress / Microcrystalline silicon / Coefficient of linear expansion |
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| Research Abstract |
We have developed the laser optical-lever bending method for the sensitive detection of small volume changes of thin semiconductor films. The obtained sensitivity of the normalized volume change was ΔV/V〜2x10 ィイD1-7ィエD1. Using this method, the light-induced expansion of ΔV/V= 10ィイD1-6ィエD1〜10ィイD1-4ィエD1 by light exposure over 100 mW/cmィイD12ィエD1 was found in hydrogenated amorphous silicon (a-Si:H)films. This light-induced volume expansions for the light exposure time over 3days and the light intensity show the correlation with the light-induced defect creations. The observed lattice expansion was a reproducible phenomenon with thermal annealing at 〜150C and has no correlation with the initial stress produced by a quratz substrate. The method for the coefficient of linear expansion has been developed and the estimated rizing temperature during the light exposure was 〜50C. We have pointed out that the light-induced expansion is a unique phenomenon of an a-Si:H itself and the light-induced d
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efect creation is resulted from structural changes of an amorphous network.
The light-induced expansion has been investigated with various deposition conditions for a-Si:H. The hydrogen dilution ratio r with SiHィイD24ィエD2 was studied. The light-induced expansion shows maximum value at r〜10 in a-Si:H films. But the microcrystalline silicon film (μc-Si:H) at r〜40 has no light-induced exansion and no light-induced defect creation. We have optimized the deposition speed, 6 nm/min, for μc-Si:H using conventional deposition method with 13.56 MHz RF power. Futhermore, we developed the new deposition method, hot-wire assisted chemical vapor deposition, which has advantage for the controll of hydrogen radicals.
The laser optical-lever bending method has applied with the evaluation of optical absorption coefficient spectra of a-Si:H films. The developed spectroscopy, the photothermal bending spectroscopy, has a high sensitivity with αd〜5x10ィイD1-5ィエD1. We have demonstrated advantages for determing the optical gap energy, defect density, impurity density, hydrogen density. Less
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