Variation of band edge, optical constant and dispersion parameters of CdS thin films due to disorder induced by fast neutron irradintion

CdS thin films were prepared by thermal evaporation method, optical constant of the deposited films were obtained from the analysis of the expirmental recorded transmittance spectral data over a wavelength range of (200-900)nm. The value of refractive index of unradiated and radiated samples are determined from these spectra using Swanepoel s model. It has been found that the dispersion data obey single-oscillator relation of the Wemple-DiDomenico model from which the dispersion parameters were determined the third order optical susceptibility χ(3) of unradiated and irradiated CdS thin film were also determined using these spectra. and the optical absorption at the fundamental absorption edge was discussed. Direct optical energy gap E opt g and Urbach (localized states) energy were also calculated for all unradiated and irradiated CdS thin films.