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Evidence for Long-range Hydrogen Motion in a-Si:H under Room-temperature Illumination Using Raman Scattering of Amorphous Tungsten Oxide Overlayer

Published online by Cambridge University Press:  17 March 2011

Hyeonsik M. Cheong ,
Se-Hee Lee ,
Brent Nelson ,
Angelo Mascarenhas  and
Sayten K. Deb
Hyeonsik M. Cheong
Affiliation:
National Renewable Energy Laboratory, Golden, Colorado 80401, U.S.A Department of Physics, Sogang University, Seoul 121-742, Korea
Se-Hee Lee
Affiliation:
National Renewable Energy Laboratory, Golden, Colorado 80401, U.S.A
Brent Nelson
Affiliation:
National Renewable Energy Laboratory, Golden, Colorado 80401, U.S.A
Angelo Mascarenhas
Affiliation:
National Renewable Energy Laboratory, Golden, Colorado 80401, U.S.A
Sayten K. Deb
Affiliation:
National Renewable Energy Laboratory, Golden, Colorado 80401, U.S.A
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Abstract

We demonstrate that one can detect minuscule amounts of hydrogen diffusion out of a-Si:H under illumination at room temperature, by monitoring the changes in the Raman spectrum of amorphous tungsten oxide as a function of illumination. The Staebler-Wronski effect, the light-induce creation of metastable defects in hydrogenated amorphous silicon (a-Si:H), has been one of the major problems that has limited the performance of such devices as solar cells. Recently, Branz suggested the hydrogen collision model that can explain many aspects of the Staebler-Wronski effect. One of the main predictions of this model is that the photogenerated mobile hydrogen atoms can move a long distance at room temperature. However, light-induced hydrogen motion in a-Si:H has not been experimentally observed at room temperature. We utilized the high sensitivity of the Raman spectrum of electrochromic a-WO3 to hydrogen insertion to probe the long-range motion of hydrogen at room temperature. We deposited a thin (200 nm) layer of a-WO3 on top of a-Si:H, and under illumination, a change in the Raman spectrum was detected. By comparing the Raman signal changes with those for control experiments where hydrogen is electrochemically inserted into a-WO3, we can estimate semiquantitatively the amount of hydrogen that diffuses out of the a-Si:H layer.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 664: Symposium A – Amorphous and Heterogeneous Silicon-Based Films-2001 , 2001 , A28.5
Copyright
Copyright © Materials Research Society 2001

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References

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