Influence of Film Thickness and Annealing Temperature on Optical Properties of Nanostructured-TiO2 Thin Films Prepared by Sol–Gel Spin Coating Technique

Abstract

TiO2 powder was found to be polycrystalline with rutile system. TiO2 films were deposited on quartz substrates by a sol–gel spin coating technique. X-ray diffraction and transmission electron microscope results have confirmed that the TiO2 films have nanostructure nature. It is found the crystallite size increased with annealing temperature. The optical constants of nanostructured TiO2 films were found to be independent of film thickness in the range from 100[Formula: see text]nm to 500[Formula: see text]nm. It is found that the optical constants and the dielectric constant of the thin films were all affected by annealing temperature. The existing allowed optical transitions in the as-deposited and annealed films were found to be direct and indirect transitions. Finally, the bandgaps of the as-deposited film were found to decrease with the annealing temperature.