Influences of carbon content and power density on the uniformity of PECVD grown a-Si1−x:Cx:H thin films

Large area electronics require large size thin films whose eventual inhomogeneities arise as a problem. Hydrogenated amorphous silicon carbide thin films (a-Si1−xCx:H) for four different source gas mixtures at two power densities were deposited by plasma enhanced chemical vapor deposition (PECVD) technique. The degree of film homogeneity was investigated through measurements of deposition rate, refractive index and optical energy gap along the radial direction of bottom electrode. Both ellipsometer at various incident angles and optical transmittance at normal incidence were used in mutual control as diagnosing tools. It seems there is a critical power density beyond which inhomogeneities of the deposited films along the radial direction of the electrode are unavoidable.