ZINC OXIDE NANOSTRUCTURES AS TRANSPARENT WINDOW LAYER FOR PHOTOVOLTAIC APPLICATION

ZnO films have been prepared by oxidizing thermally evaporated Zn metal. Crystallization appears to be influenced by both annealing temperature and time. XRD result reveals the presence of (100), (002) and (101) diffraction peaks for films annealed at 2500 degrees C, also intensity of the peaks show an increase with increase in post-annealing temperature to 400 and 550 degrees C. FWHM of the peaks decrease with increase in annealing temperature which reveals that crystallinity of films is improved. The transparent sample has been characterized by SEM, XRD UV-VIS spectroscopy and RT measurements. Electron microscopy confirms platelets shaped crystals parallel to the substrate with average width of about 0.33-0.64 mu m. The optical band gap lie in the range 3.06-3.30 eV showing an improvement in transparency with annealing temperature for window application. The annealing temperature appears to be important parameters for molecular packing in the solid state structure and influence the properties of the films. Films annealed at elevated temperatures show comparatively higher electrical resistivity and optical band gap which is due to the transformation of Zinc to Zinc Oxide at higher annealing temperature.