XRD, OPTICAL AND VIBRATIONAL PROPERTIES OF ANNEALED CADMIUM SULFIDE FILMS

Abstract

Cadmium sulfide (CdS) films have been formed using an ultrasonic spray pyrolysis method. These films were annealed at a temperature range of 200-500oC in air for 5 hours. To investigate the effects of annealing on the vibrational, structural, optical and morphological properties of cadmium sulfide films, X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, UV-visible spectroscopy (UV–vis) and atomic force microscopy (AFM) were used, respectively. The XRD spectra indicated that the films have polycrystalline hexagonal nature. According to XRD results, increase in the annealing temperature causes an increase in crystallite size. The optical band gap of the CdS films have been calculated at different annealing temperatures and are found to be in the range of 2.40-2.44 eV. Raman results exhibited two peaks attributed to the 1LO (300cm-1) and 2LO (601cm-1) modes of hexagonal CdS. The chemical bonding has been analyzed by FTIR spectra. The vibrational peaks in the FTIR spectra of the films located at 550–715 and 844–1160 cm-1 correspond to the Cd–S and C– O phonon modes, respectively. The morphological properties of all the films were determined by AFM images. The annealing temperature caused a change in color images of films.