Structural and Optical Characterization of ZnO Thin Films bySol-gelTechnique

Abstract

The ZnO thin films have been fabricated on commercial glass substrates by sol-gel spin coating process and annealing temperatures 300oC, 400oC and 500oC. X-ray diffraction (XRD) and UV-VIS-NIR are used to characterize ZnO thin films. X-ray diffraction study show that all the films prepared in this work have hexagonal wurtzite polycrystalline structure, with lattice constants a=b=3.260Å, c=5.215Å. A significant increase in the XRD peak intensities for the ZnO films after annealing can be observed. Scherrer's formula was used to calculate crystallite size. The optical band gap energy of thin films is found to be direct allowed transition with average value 3.25 eV. Urbach energy is calculated. The average value of transmittance of thin films in visible range is found to be 9%-93%.

Keywords

ZnO, Sol-gel, XRD, Band gap