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Improvement in a-Si:H Properties by Inert Gas Plasma Treatment

Published online by Cambridge University Press:  10 February 2011

E. Maruyama
Affiliation:
New Materials Research Center, Sanyo Electric Co., Ltd. 1-18-13 Hashiridani, Hirakata, Osaka 573, Japan
Y. Hishikawa
Affiliation:
New Materials Research Center, Sanyo Electric Co., Ltd. 1-18-13 Hashiridani, Hirakata, Osaka 573, Japan
M. Tanaka
Affiliation:
New Materials Research Center, Sanyo Electric Co., Ltd. 1-18-13 Hashiridani, Hirakata, Osaka 573, Japan
S. Kiyama
Affiliation:
New Materials Research Center, Sanyo Electric Co., Ltd. 1-18-13 Hashiridani, Hirakata, Osaka 573, Japan
S. Tsuda
Affiliation:
New Materials Research Center, Sanyo Electric Co., Ltd. 1-18-13 Hashiridani, Hirakata, Osaka 573, Japan
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Abstract

The modification of surface reactions with an inert gas plasma treatment method has been investigated for the first time in order to improve the properties of a-Si:H for solar cells. The deposition of a thin a-Si:H layer and exposure to inert gas plasma such as He, Ar or Xe were repeated by using RF plasma CVD at a substrate temperature of 200 °C. It has been found that the hydrogen content (CH) can be controlled in a wide range from about 18 atomic% to about 35 atomic%, although it is a hydrogen-free process. Experimental results show that the change in CH of a-Si:H films is mainly determined by the decrease in CH of the treated a-Si:H surface and the increase in CH of the a-Si:H deposited on the treated surface. Furthermore, the plasma treatment probably promotes the surface reaction, which reduces SiH2ISiH and CH. Consequently, wide-gap (1.64 eV by ( a h ν )1/3 versus h ν plots, 1.75 - 1.85 eV by Tauc's plot) a-Si:H films with high stabilized photoconductivity (> 10-5 Ω-1cm-1 under AM-1, 100 mW/cm2 irradiation) have been obtained by the inert gas plasma treatment method.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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