Resonant Raman scattering of a-SiNx:H

Micro-Raman measurements were carried out to investigate the microstructure of amorphous silicon-nitrogen alloy (a-SiNx:H) samples with different N contents prepared by plasma enhanced chemical vapor deposition (PECVD). Resonant Raman effect was discovered by using 647.1- and 514.5-nm excitation wavelengths. The frequency of TO mode downshifts with increasing photon energy without varying its width, while LO mode expands to a great extent. The frequency-dependent shift of TO band is explained by heterogeneous structure model and quantum confinement model, and the width expansion of LO mode may be related to the overlapping of LA and LO bands. (C) 2001 Elsevier Science B.V. All rights reserved.