The effect of annealing temperature on the structural and optical properties of nanostructure ZnO

In this research, the effect of annealing temperature Ta on the structural and optical properties of ZnO nanostructure which was prepared by spray pyrolysis method, was investigated. Zno films prepared by spray pyrolysis technique on glass substrate with thickness 300 nm using: Zinc acetate Zn (CH3COOV2H2O, with purity of 99.6% and distilled water. After that the films were annealed at various temperatures (673, 7 773 and 873 K). X-ray diffraction studies show that the structure of all ZnO films is polycrystalline with hexagonal wurtizte structure with preferential orientation in the (002) direction. The post-deposition annealing of the film from (R.T to 873) K increases the intensity of (002) peak corresponding to c-axis orientation in addition with the decrease in full width at half maxima (FWHM). The optical measurement showed that the nature of the optical transition has been direct allowed with average band gap energies have tendency to decreases from (3.28 -2.93) eV with increasing of Ta excepted it was increased to 3.21 eV at 773 K. The extent and nature of transmittance and optimized band gap of the material assure to utilize it for photovoltaic applications.