Doping, vacuum annealing, and thickness effect on the physical properties of zinc oxide films deposited by spray pyrolysis

Gallium, aluminum, and indium-doped ZnO (ZnO:Ga, ZnO:Al, and ZnO:In) films have been deposited by the chemical spray method on sodocalcic substrates. The effect of different dopant elements, a post-annealing treatment in vacuum, and the film thickness on the electrical, optical, structural, and morphological properties of the films has been investigated. The best electrical properties were observed in the thickest indium-doped ZnO films; the lowest electrical resistivity was of the order of 10−3 Ω cm. In general, the optical transmittance value in the visible spectrum oscillated around of 87% in the thinnest films. The structural and morphological properties of ZnO:Ga and ZnO:Al films are similar, as in both cases the (0 0 2) orientation is dominant on the rest of the peaks, and both surfaces have a rough appearance. In the case of ZnO:In films, the (1 0 1) was the preferential growth orientation, and the surfaces seem to be smoother than the corresponding ZnO:Ga and ZnO:Al films.