Influence of annealing temperature on structural and optical properties of CdS thin films prepared by sol-gel spin coating method

Cadmium Sulphide (CdS) thin films were deposited on glass substrates by sol-gel spin coating method taking cadmium nitrate and thiourea as the precursor solutions. The influence of annealing temperature on the structural, optical and surface morphological properties of the films was studied. The crystallographic structure and crystallite size were determined from the X-Ray Diffraction study. It reveals that the films have a predominant hexagonal crystal phase with a preferential (0 0 2) plane. Transmittance of the deposited films was significantly higher in the visible region. The calculated optical band gap of the films decreases with increase in annealing temperature. The photoluminescence spectra show that the intensity of PL emission peaks found to decrease in intensity, with increase in annealing temperature. SEM studies reveal that the grains are spherically shaped and distributed uniformly over the entire surface of the substrate. These examined properties of the films show its feasibility for application in optoelectronic devices, especially for solar cells.