Photoluminescence Properties of a-SiC:H Films Grown by Plasma Enhanced Chemical Vapor Deposition from SiH₄+C₂H₂ Gas Mixtures

The films of a-SiC:H were deposited by plasma enhanced chemical vapor deposition system from SiH₄+ C₂H₂ gas mixtures. The C-rich a-SiC:H films were easily obtained by using C₂H₂ gases due to the low dissociation energy of C₂H₂ molecule in the plasma. Thus, the carbon was effectively incorporated into a-Si:H network. Although the defect state densities were proportional to carbon content in a-SiC:H films, the photoluminescence intensities were not directly related with defect density, yet increased with the carbon content increasing. The infrared spectra indicated that CH_n groups as clusters were incorporated mainly into a-SiC:H network. The little correlation of the PL integrated intensity with defect state density suggested that luminescence was associated with clusters as a largely intracluster process.