Effects on Structural and Electro-Optical Properties of Iron Incorporation to p-Zinc Oxide (ZnO) Thin Films Deposited by Dip-Coating Process

Abstract

In this paper, thin films of undoped Zinc Oxide (ZnO) and Fe-doped Zinc Oxide (ZnO: Fe) were prepared by a sol-gel process using the technique of coating .The effect of iron (Fe) incorporation on structural and electro-optical properties of ZnO films were investigated. The X-ray diffraction patterns showed that Fe-doping in Zinc Oxide thin film has affected their structural properties. All the films had polycrystalline structures, with a preferential growth along ZnO (002) plane. The crystallite size was calculated and found in the range of 25-40 (nm).The thin films were under compressive stress. The X-ray photoelectron spectroscopy results indicated that a high quality of ZnO and ZnO: Fe thin films were obtained, which are in good agreement with the results of the dislocation densities obtained from X-ray diffraction. The optical transmittance measurement revealed a high transmittance (> 85%) in the visible region and the role of Fe dopant in ZnO lattice was clearly illustrated by decreasing the optical gap and expanding the Urbach tail. The determination of type carrier conductivity affected by the incorporation of iron atoms in resistive ZnO to p-type conductivity was demonstrated by the electrical system measurement.