Infrared vibrational spectra of hydrogenated amorphous and microcrystalline silicon-carbon alloys

We have performed a detailed study of composition and vibrational excitations of amorphous and microcrystalline silicon-carbon alloys grown with high hydrogen dilution by plasma-enhanced chemical vapour deposition. The strengths of characteristic vibration bands show variations at the amorphous-crystalline transition and with the degree of crystallinity, providing a very useful framework for understanding the structure of the alloys. The composition of the amorphous tissue constituting the matrix of the films has been deduced. The matrix can be considered 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.