دراسة تاثير السمك على الخصائص البصرية للاغشية الرقيقة CdS

Thin films of cadmium sulfide (CdS) of different thickness, 200, 400 and 600 nm , were deposited onto glass substrates by thermal evaporation technique. The effect of films thickness on optical properties was investigated. The optical parameters investigated include transmittance, absorbance, and reflectance spectra, in addition to optical band gap, refractive index, extinction coefficient, optical conductivity and complex dielectric constant. It was found that the optical parameters depend markedly on the film thickness. The spectral absorption coefficient and optical band gap energy of films at the fundamental absorption region were determined using the spectral data of transmittance measurements within the wavelength range 350-900 nm. It was found that the optical band gap decreases from 2.55 – 2.50 eV when the films thickness increase from 200 nm to 600 nm . All the films were found to exhibit high transmittance (83-99%), low absorbance and low reflectance in the visible and near infrared region up to 900 nm.