IMPROVEMENT IN OPTICAL TRANSPARENCY OF SIC MEMBRANE BY MODULATING SOURCE GAS RATIO IN CHEMICAL-VAPOR-DEPOSITION

A method to improve the optical transparency of a SiC membrane is stud ied by modulating the source gas carbon-to-silicon ratio (C/Si) during chemical vapor deposition. As a result of an investigation conducted under different C/Si conditions, the optical transparency was found to be highest at C/Si=0.9. Optical transparency decreased at lower C/Si probably due to the increase of surface roughness, and at higher C/Si due to the degradation of crystal quality. By alternate deposition und er the condition of C/Si=0.8 and 0.95, the SiC membrane with an optica l transparency of 68% was obtained without applying an antireflection coating.