Abstract
We have attempted to observe changes in the Raman scattering spectrum of a-Si:H due to light exposure. We do not find any detectable shift of the position or change in the width of the TO phonon peak. We find, however, other unexpected degradation phenomena in the Raman spectrum of a-Si:H samples which are attributed to light induced changes in the high energy tail of room temperature luminescence. Raman scattering has a relatively large (10-20% of TO peak height) broad background which extends to 2000cm-1 in the Stokes region and tails into the anti-Stokes region. Multiple phonon processes, geminate radiative recombination and surface oxide contributions are considered. Degradation phenomena and the broad background signal are observed in a-Si:H deposited on different substrates as well as in free-standing films. Degradation processes in bare fused quartz substrates are also investigated. Small structural changes surrounding the light-induced defects are proposed and discussed.
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Acknowledgement
The authors are grateful to Prof. H. Fritzsche for his valuable contribution and to Profs. R.W. Collins, K. Matsuishi, S. Onari for extensive consultations, and to Drs. G. Ganguly, R. Hayashi, T. Kamei, K. Saitoh for providing and preparing the samples. P. Stradins thanks the Science and Technology Agency of Japan for a fellowship.
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Stradins, P., Kondo, M., Hata, N. et al. Light-Induced Degradation Effects in a-Si:H Observed by Raman Scattering Measurements. MRS Online Proceedings Library 507, 723–728 (1998). https://doi.org/10.1557/PROC-507-723
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DOI: https://doi.org/10.1557/PROC-507-723