Versatile r.f. magnetron sputtering doping method to produce aluminum-doped zinc oxide films

Aluminum-doped zinc oxide Al:ZnO (AZO) is a non-toxic material applied as a transparent conductive oxide film. In this study, we report on the structural, optical, and electrical properties of AZO films obtained by thermally oxidizing aluminum-doped Zn films produced by a versatile and low-cost method of doping using the magnetron sputtering technique deposition. We use aluminum wire above the zinc target to produce Al:Zn films. The influence of r.f. power and different Al wire lengths on the AZO film properties were studied. The resulting AZO films exhibited Al concentrations of up to 2.85% and an optical gap between 3.22 and 3.29 eV. The transmittance was greater than 80% for all samples, and the electrical resistivity decreased by two orders of magnitude with Al doping. As a result, the sample with an aluminum concentration of approximately 1% had the lowest resistivity. In this work, it was possible to relate the lower resistivity with larger grain size and smaller concentrations of defects or vacancies.