Optical and Structural Properties of Thermally Evaporated CdS Thin Films

Cadmium sulphide thin films were deposited by the vacuum evaporation technique onto well clean glass substrate held at 200 degrees C. The films have been annealed, in air, at two different temperatures, 300 degrees C and 350 degrees C. X-ray diffraction studies confirmed the polycrystalline hexagonal CdS phase formation. The structural parameters such as lattice parameter, crystallite size, dislocation density and strain have been evaluated. The transmittance and absorbance are measured at normal incidence, in the spectral range 500nm-1100nm. The transmittance data analysis indicates a direct band gap ranging from 2.49eV-2.28eV. Refractive index of the films has been evaluated in the wavelength lambda = 600nm.