Nanostructure of Al-ZnO Thin Films on ITO/Glass Substrate Prepared via Sol-Gel Spin Coating Process

Abstract

Solar energy is probably the most important source of renewable energy available today. ZnO is a potential material for the fabrication solar cell. Zinc oxide (ZnO) nano-structure semiconductors have been recently gained much attention in the electronic and optical device applications. ZnO is a compound semiconductor, which has a high extention band gap (E= 3.37 eV) at room temperature (RT) with a Wurtzite crystal structure. In particular ZnO can be employed as the transparent conducting oxide (TCO) in solar cell applications due to its high productivity, non-toxic, low cost, and excellent electrical conductivity. In this study, aluminum doped ZnO (AZO) polycrystalline films have been fabricated on ITO/substrates via a sol-gel spin-coating method. The quantity of aluminum doping in the solution was 4.0 %. After synthesis, the films were pre-heated at 300°C for 25 min and after that the films were inserted in a Tub-furnace and post-annealing at 450°C to 750°C for 1 h. The microstructural and structural properties of AZO films were studied through X-ray diffraction (XRD), UV-Vis NIR and scanning electron microscope (SEM) analysis. The TCO applications of the transmittance of samples were also examined. The results showed that the annealing temperature does not seriously affect on the transmittance of AZO films over the visible range.