Effect of annealing on the optical properties of thermally evaporated ZnO films

Two zinc oxide samples with different film thicknesses have been thermally evaporated on unheated glass substrate using ZnO high-purity powder. The films were subjected to post-deposition annealing in air at different temperatures. X-ray diffraction confirmed that the films in the as-deposited as well as after annealing are in the amorphous state. The optical properties were studied by transmittance and reflectance measurements. The integrated visible (T-vis), and solar, T-sol, transmittance were calculated. The dependence of absorption coefficient and the refractive index on wavelength before and after post-deposition heat treating was also reported, (C) 2001 Elsevier Science Ltd. All rights reserved.