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Structural and optoelectronic properties of amorphous and microcrystalline silicon deposited at low substrate temperatures by RF and HW CVD

Published online by Cambridge University Press:  15 February 2011

P. Alpuim
Affiliation:
Instituto de Engenharia de Sistemas e Computadores (INESC), Rua Alves Redol, 9, 1000 Lisboa, Portugal, palpuim@eniac.inesc.pt
V. Chu
Affiliation:
Instituto de Engenharia de Sistemas e Computadores (INESC), Rua Alves Redol, 9, 1000 Lisboa, Portugal
J. P. Conde
Affiliation:
Department of Materials Engineering, Instituto Superior Técnico, 1049-001 Lisboa, Portugal
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Abstract

The structural and optoelectronic properties of silicon thin films prepared by hot wire chemical vapor deposition and radio frequency plasma enhanced chemical vapor deposition are studied in the range of substrate temperatures (Tsub)from 100 °C to 25 °C. The defect density, structure factor and bond angle disorder of amorphous silicon films (a-Si:H) deposited by both techniques are strongly improved by the use of hydrogen dilution. Correlation of these structural properties with important optoelectronic properties, such as photo-to-dark conductivity ratio, is made. Microcrystalline silicon (μc-Si:H) is obtained using HW with a large crystalline fraction for hydrogen dilutions above 85% independently of Tsub. The deposition of μc-Si:H by RF requires increasing the hydrogen dilution and shows decreasing crystalline fraction as Tsub is decreased. The properties of the low Tsub films are compared to those of samples produced at 175 °C and 250 °C in the same reactors.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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