Influence of Thickness and Annealing on Some Physical Properties of Zinc Oxide Films

Abstract

Zinc oxide transparent conductive films were deposited on glass substrates at 400 C using chemical spray pyrolysis method. The effect of annealing of ZnO samples with the increase in thickness has been studied. The X-ray diffraction results indicate that the polycrystalline films exhibited a distinguished orientation along (002) direction with a hexagonal wurtzite phase type. It is found that good crystallinity is obtained in the samples annealed at 500 C. All films showed an average transmittance of about 85% measured by UV/VIS/NIR spectrophotometer. The grain size and lattice parameters of films were computed. The grain size increases as thickness increases. Hence the values of the optical gap energy (Eg) are found to be in the range of 3.238 to 3.273 eV without annealing and in the range of 3.252 to 3.280 eV with annealing when the thickness varies from 355 to 445 nm.