STUDIES ON STRUCTURAL , OPTICAL AND ELECTRICAL PROPERTIES OF CADMIUM SULPHIDE THIN FILMS

Cadmium sulphide (CdS) thin films were synthesized by chemical bath deposition (CBD) method. The XRD, SEM, AFM, UV-Visible absorption spectrum, dielectric studies and photoconductivity measurements were used to characterize the CdS films. The X-ray diffraction (XRD) analysis showed that the prepared CdS films were polycrystalline with cubic structure. The crystallite size was determined from the broadenings of corresponding X-ray diffraction peaks by using Debye Scherrer’s formula. Scanning Electron Microscopy (SEM) and atomic force microscopy (AFM) revealed that the grains were uniformly distributed over the surface of the substrate for the CdS films. The optical properties were studied using the UV-Visible absorption spectrum. Optical constants such as band gap, refractive index, extinction coefficient and electric susceptibility were determined from UV-Visible absorption spectrum. The dielectric studies of CdS thin films were studied for different frequencies and different temperatures. The temperature dependent conductivity study confirmed the semiconducting nature of the films. The activation energy of the CdS films was calculated. Photoconductivity measurements were carried out in order to ascertain the positive photoconductivity of the CdS thin films.