Optical properties of amorphous silicon nitride thin-films prepared by VHF-PECVD using silane and nitrogen

Hydrogenated amorphous silicon nitride (a-Si1-x N x :H) thin-films with x between 0.42 and 0.58 were deposited from silane diluted in nitrogen gas by VHF PE-CVD using a novel method for impedance matching. We determine the refractive index dispersion relations and the optical absorption edge information from the transmission spectra and report on the changes in the optical properties as the composition is varied. The optical properties of these films are similar to those of silicon nitride deposited using the more conventional silane-ammonia mixtures.