Structural and optical properties of chemically deposited CdCr2S4 thin films

Abstract

Reproducible and good quality CdCr2S4 thin films with different thicknesses were deposited on microscopic glass substrates using the chemical bath deposition process. The x-ray and electron diffraction analysis revealed that the as-deposited films were polycrystalline cubic phase. The optical constants of the deposited films were obtained from the analysis of the experimental recorded transmission and reflectance spectral data over the wavelength range 300–2500 nm. It has been found that the refractive index and extinction coefficient are almost independent of the film thickness. The complex dielectric constants of CdCr2S4 films have been calculated in the investigated wavelength range. An analysis of the optical absorption data of the as-deposited films revealed an optical direct transition with the estimation of the corresponding bandgap value. It was found that the refractive index dispersion data obeyed the single oscillator of the Wemple–DiDomenico model, from which the dispersion parameters and the high-frequency dielectric constant were determined. The electric free carrier susceptibility and the carrier concentration to the effective mass ratio were estimated according to the model of Spitzer and Fan.