Effect of ambient hydrogen sulphide on the optical properties of evaporated cadmium sulphide films

Abstract The optical constants ( n , k ) of evaporated cadmium sulphide (CdS) thin films deposited in an ambient atmosphere of hydrogen sulphide (H 2 S) were determined over the wavelength range 350–800 nm from the measurement of reflection and transmission spectra. Low ambient atmosphere of H 2 S was obtained by thermal decomposition of thiourea inside the vacuum chamber. Cadmium sulphide thin films deposited with H 2 S ambient are more uniform, more adherent, pin hole free and have better crystallinity in comparison with the films without H 2 S atmosphere as inferred by the sharpness of the absorption spectra. Such films are inherently better suited for device fabrication.