Preparation and characterization of ZnO:Al semiconductor thin film by sol-gel method

ZnO:Al thin films have excelled as a transparent conductive oxide (TCO) in solar energy and electronic areas. In this work, good uniformity ZnO:Al thin films were obtained by sol-gel dip-coating with different amount of Al dopant and number of coatings. The amount of Al dopant, in terms of %Al/Zn, was varied from 0 to 2 and number of coatings from 4 to 6. Optical, electrical and structural properties were evaluated. ZnO:Al films were characterized by UV-Vis spectroscopy and presented transmittance greater than 80% in visible range. Some samples have showed anti-reflective properties in specific regions in visible range and Moss-Burstein shift was observed. Resistivity was evaluated by 4-point method and samples with 1,0%Al/Zn led lower resistivity, while the 1,0%Al/Zn-6 coatings film showed the lowest resistivity. Resistivity decreases until 1,0%Al/Zn and increases after this point. As the coating number increases, the film resistivity decreases. XRD results showed that all samples were crystalline. It was observed that the intensity of XRD peaks and crystallite size decrease with % Al/Zn increasing, because the increasing of Al content deteriorates film crystallinity. High transmittance, semiconductor, homogenous ZnO:Al thin films were obtained by a stable sol-gel solution. (author)