The Effect of Bath Temperature on the Chemical Bath Deposition of Copper Sulphide Thin Films

Copper sulphide thin films were deposited onto indium tin oxide glass substrates by chemical bath deposition technique. The chemical bath contained copper chloride and sodium thiosulfate acted as Cu^2+ and S^2- ion sources, respectively. The influence of bath temperature towards the properties of copper sulphide films was investigated. The deposited films were characterized with X-ray diffraction, atomic force microscopy and UV-Vis spectrophotometer. XRD studies demonstrated that the thin films had hexagonal structure and confirmed the improvement of crystallinity of the films by increasing the bath temperature. Meanwhile, the surface roughness, film thickness and grain size were also increased with increasing of bath temperature from 25 to 45 °C. However, the films deposited at 25 °C showed homogeneous and uniform structure according to AFM images. Optical absorption analysis indicated that the band gap values were increased from 2.5 to 2.7 eV as the bath temperature was decreased from 45 to 25 °C. The XRD, AFM and optical absorption analysis results suggested that the influence of bath temperature on the CuS thin films properties was significant. Therefore, the bath temperature was one of the main deposition parameters that control the properties of semiconductor thin films.