INFRARED VIBRATIONAL-SPECTRA OF HYDROGENATED AMORPHOUS AND MICROCRYSTALLINE SILICON-CARBON ALLOYS - A COMPARISON OF THEIR STRUCTURE

We have performed a detailed study of composition and vibrational exci tations of amorphous and microcrystalline silicon-carbon alloys grown with high hydrogen dilution by plasma-enhanced chemical vapour deposit ion. The strengths of characteristic vibration bands show variations a t the amorphous-crystalline transition and with the degree of crystall inity, providing a very useful framework for understanding the structu re of the alloys. The composition of the amorphous tissue constituting the matrix of the films has been deduced. The matrix can be considere d a covalent network where 1 in 9 bonds are terminated by hydrogen and the carbon can be present in the tetrahedral, polymeric or graphitic form.