Structural and optical properties of silicon carbonitride thin films deposited by reactive DC magnetron sputtering

In this study, silicon carbonitride thin films of variable compositions were deposited on glass and AISI M2 high-speed steel substrates by reactive DC magnetron sputtering of high purity silicon target using CH₄ and N₂ as reactive gases. The composition of the coatings was modified by the change in the reactive gas flow ratios. Microstructural properties were investigated by cross-sectional SEM analyses. Spectrophotometer was used to measure the optical transmittance and reflectance of silicon carbonitride thin films over the spectral range from 280 to 1000 nm. The optical constants and band gap values of the films were further evaluated with respect to the gas flow rate. The results of analyses and calculations provided the information about the relationship between the reactive gas flow rates, microstructure, optical constants and band gap values of silicon carbonitride films.