The Effect of Thickness and Annealing on Structural and Optical Properties of ZnO: Al Thin Films

Abstract

ZnO: Al transparent conductive thin films was prepared by home-made chemical vapor deposition system at (500oC). Zinc acetate dehydrate precursor was used to obtain ZnO films and aluminum nitrate nonahydrate as a dopant source to prepare different thickness (0.539µm, 0.369µm, 0.227µm, 0.057µm) of ZnO: Al thin films. In this study the structural and optical properties of thin films were investigated. X-ray measurements revealed that films structure was polycrystalline of hexagonal quartzite type with preferential orientation along (002) direction. The surface morphology of the films was determined by atomic force microscope (AFM) and the measurements indicate an increase in the smoothness of the upper surfaces after annealing (2.93 nm-1.6nm), and the grain sizes of the sample was in the Nano metric scale. The effect of thickness and annealing time on optical properties of the films were investigated. From the measurements, it was found that the transmittance decrease with increasing thickness. On the other hand, the transmittance and the optical gap increase with increasing the annealing time for low thicknesses, while for the higher thicknesses, a little changes were observed