Effect of the annealing temperature on transparency and conductivity of ZnO:Al thin films

Highly aluminum-doped zinc oxide (ZnO:Al) films were grown by rf-magnetron sputtering at low temperature from aerogel nanoparticles and characterized by structural, electrical and optical techniques. Nanoparticles with a size of about 30 nm were synthesized by sol–gel method using supercritical drying in ethyl alcohol and annealed at different temperatures with different gas atmospheres. The ZnO films were polycrystalline textured, preferentially oriented along the (002) crystallographic direction normal to the film surface. The films show within the visible wavelength region an optical transmittance of more than 90% and low electrical resistivity of 10− 3 Ω cm at room temperature.