Effect of annealing temperature on the values of absorption peaks of ZnO films

The aim of this work is to investigate the optical properties of zinc oxide thin films under different post-annealing temperatures from 400 to 600 ºC with a special emphasis on the absorption edge. The optical reflectance spectra in the wavelength range 300 – 2500 nm were used to compute the absorption coefficient. The values of peaks maximum in derivation of reflectance respect to wavelength, dR/dλ, of films exhibit values for optical gaps from about 3.12 – 3.4 eV. The values of the fundamental indirect band gap obtained from Tauc model are about 3.14 – 3.2 eV.