1Effects of sputter power, gas pressure and substrate temperature on the structure and optical properties of CdS thin films

CdS is deposited on transparent conductive oxide (TCO)-coated glass substrate by radio frequency (r.f.) magnetron sputtering method. The X-ray diffraction (XRD) measurements revealed that CdS films were polycrystalline with the hexagonal wurtzite structure present only. The same conclusions as described below are arrived at from the photoluminescence (PL) and UV-vis absorption spectra measurements. When the power increases or the gas pressure decreases, the grain size and the film thickness increases, and then lead to the increase of stress in films which results in the decrease of energy band gap. The substrate temperature also has an effect on the strain in the films.