Pulsed laser deposition of SiC films on fused silica and sapphire substrates

Abstract

350-nm-wavelength laser ablation of ceramic SiC targets has been used to deposit SiC films on fused silica and R-cut sapphire at substrate temperatures from 300 to 1150°C. The films deposited above 800°C show (111) and (222) x-ray-diffraction bands from crystal planes parallel to the substrate. The bandwidths decrease and the integrated intensities increase with deposition temperature. The crystallite dimension for the highest-temperature films is in the order of 50 nm. The diffraction peaks are absent for the films deposited at the lower temperatures. Analysis of optical transmission spectra of the high-temperature films shows a lowest-energy gap near 2.2 eV which is the value for cubic SiC. The low-temperature films show smaller and variable gaps. The room-temperature resistivities of the former are low, from 0.02 to 0.1 Ω cm whereas the latter are insulating. Film thicknesses and deposition rates ranging from 0.2 to over 0.6 Å/pulse are obtained from the spectra and by monitoring of the interference oscillations in the infrared emission through the film during deposition.