Optical constants of Zinc sulphide ZnS thin films for different annealing Temperature


Zinc sulphide ZnS thin films were prepared by the spray pyrolysis (SP) technique on glass substrates at different temperatures (450, 500,550 and 600°C). Transmittance and absorbance measurements in the wavelength range (200–1000 nm) were used to calculate the refractive index n and the extinction coefficient k. The optical band gap Eg(=E_(opt.)^WD), optical conductivity σopt, complex dielectric constant ε1, ε2, ε∞, relaxation time τ, average interband oscillator wave length λo average oscillator strength So, N/m*(N the free charge carrier concentration , m* the effective mass of the free charge carrier ) and dissipation factor tanδ were determined. The analysis of the optical absorption data indicates that the optical band gap was indirect transitions. According to Wemple and Didomenico method, the optical dispersion parameters Eo and Ed were determined.