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Characterization of Microcrystalline Transition from Amorphous Silicon as a Function of Hydrogen Dilution and Substrate Temperature of Hot-wire CVD

Published online by Cambridge University Press:  01 February 2011

Keda Wang ,
Haoyue Zhang ,
Jian Zhang ,
Jessica M. Owens ,
Jennifer Weinberg-Wolf ,
Daxing Han ,
Lynn Gedvilas  and
Brent Nelson
Keda Wang
Affiliation:
Department of Physics & Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255
Haoyue Zhang
Affiliation:
Department of Physics & Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255
Jian Zhang
Affiliation:
Department of Physics & Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255
Jessica M. Owens
Affiliation:
Department of Physics & Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255
Jennifer Weinberg-Wolf
Affiliation:
Department of Physics & Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255
Daxing Han
Affiliation:
Department of Physics & Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255
Lynn Gedvilas
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401
Brent Nelson
Affiliation:
National Renewable Energy Laboratory, Golden, CO 80401
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Abstract

a-Si:H films were prepared by hot wire chemical vapor deposition. One group was deposited at a substrate temperature of Ts=250°C with varied hydrogen-dilution ratio, 0<R<10; the other group was deposited with fixed R=3 but a varied Ts from 150 to 550°C. IR, Raman and PL spectra were studied. The Raman results indicate that there is a threshold value for the microstructure transition from a- to μc-Si. The threshold is found to be R ≈ 2 at Ts = 250°C and Ts ≈ 200°C at R=3. The IR absorption of Si-H at 640 cm-1 was used to calculate the hydrogen content, CH. CH decreased monotonically when either R or Ts increased. The Si-H stretching mode contains two peaks at 2000 and 2090 cm-1. The ratio of the integral absorption peaks I2090/(I2090+I2090) showed a sudden increase at the threshold of microcrystallinity. At the same threshold, the PL features also indicate a sudden change from a- to μc-Si., i.e. the low energy PL band becomes dominant and the PL total intensity decreases. We attribute the above IR and PL changes to the contribution of microcrystallinity, especially the c-Si gain-boundaries.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 715: Symposium A – Amorphous and Heterogeneous Silicon-Based Films-2002 , 2002 , A17.2
Copyright
Copyright © Materials Research Society 2002

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