CHEMICAL BONDING ANALYSIS OF A-SIC - H FILMS BY RAMAN-SPECTROSCOPY

The local structure of hydrogenated amorphous silicon-carbon films is investigated by Raman spectroscopy. The data are analyzed over a wide frequency range including Stokes and anti-Stokes scattering, for diffe rent alloy compositions. Their interpretation is based on a lineshape analysis of the spectra by using the density of vibrational states of the different crystalline materials, and taking into account multiple- order processes. The tendency to chemical ordering into a sp3 connecte d network prevails in Si-rich films. The higher the carbon amount, the less ordered are the films, due to the presence of a mixed sp2-sp3 po lymeric phase. The results are compared with those deduced from variou s other techniques and theoretical predictions.