ZnO:Al Properties Study for a Transparent Electrode Application

This work deals with the electrical, optical and structural properties of Aluminum (Al) doped Zinc Oxide (ZnO) thin films. The layers were prepared by the sol–gel method and deposited onto glass substrates using the spin coating technique. The effect of Al incorporation on the electrical and optical properties of the samples was investigated by the four-probe method and the UV–Vis spectroscopy while the X-ray diffraction technique was used to investigate their structure. According to the transmittance curves analysis, the films exhibited a high optical transmission up to 90%. It has been found that the apparent optical gap decreases with increasing the doping level. The electrical resistivity was found to be in the range of 10−3 Ω. cm for the doped films. All the samples exhibited a hexagonal Wurtzite structure. The best performances were obtained for the 4% Al doped film presenting the highest conductivity and crystallinity combined to a good transparency. These low-cost films could be successfully used as transparent electrodes in Photovoltaic applications.