Microstructure and the Urbach Edge in Glow Discharge Deposited a-SiC:H

Abstract

Photothermal deflection spectroscopy, infrared, and Raman measurements are presented for a series of a-SiC:H samples containing different amounts of microstructure. The Urbach edge is seen to widen systematically as the film microstructure increases, but the width of the Raman transverse optical mode remains unchanged. We argue that the increase in Urbach edge width with increasing C content is due entirely to the increase in microstructure. In addition, from the invariance of the Raman measurements with increasing microstructure and the assumed sensitivity of the Raman technique to surface states on the interior surfaces of these microstructural features, we are able to place lower limits on the size of these features. Such sizes are corroborated by preliminary small angle xray scattering measurements on identically prepared samples.

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Mahan, A.H., Mascarenhas, A., Williamson, D.L. et al. Microstructure and the Urbach Edge in Glow Discharge Deposited a-SiC:H. MRS Online Proceedings Library 118, 641 (1988). https://doi.org/10.1557/PROC-118-641

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