Characterization of CdS films prepared by chemical-bath deposition

Thin films of cadmium sulphide were deposited on glass substrates by the chemical bath deposition method. The results of measurements on the spectral response of photoconductivity, the optical absorption coefficient and the x-ray diffraction were used for the characterization of films. This study revealed that CdS films have tensile strain along the hexagonal (002) planes. The dependence of strain on the grain size is responsible for the variation of energy bandgap with the film thickness. Annealing in air, and at a temperature greater than 150 °C, relaxes the strain, reduces the extent of disorder in grain boundaries, reduces the energy bandgap and improves the mobility-lifetime product for photogenerated carriers.