Abstract
Nanocrystalline Se0.8Te0.2 films were grown on quartz substrates by using thermal evaporation technique. Structural and optical properties of as-grown and annealed samples were investigated with XRD, SEM and UV-visible spectroscopy. The x-ray diffraction pattern at room temperature shows that the sample are formed in single phase with monoclinic crystal symmetry having space group Cm. Surface morphology of the glass as-grown film was investigated via scanning electron microscopy (SEM). The typical diameter of as-grown nanocrystalline sample is found to be 50 nm, which is consistent with crystallite size calculated by XRD data using Scherrer equation. The UV-visible absorption spectra of the nanocrystals show that the optical band gap of as-grown and annealed samples are situated systematically in the range of 2.10-1.95 eV, which is quite larger than the bulk phase of the materials. The results have been explained on the basis of the close interplay between the structural and optical properties.