Ga-doped ZnO thin films: Effect of deposition temperature, dopant concentration, and vacuum-thermal treatment on the electrical, optical, structural and morphological properties

Transparent conductive Ga-doped Zn oxide (ZnO:Ga), thin films were prepared by the chemical spray technique using Zn acetate and Ga pentanedionate as precursors of Zn and Ga, respectively. The effect of the deposition temperature, Ts, dopant concentration [Ga/Zn], and a vacuum-annealing treatment on the physical properties of the ZnO:Ga thin films was analyzed. The electrical and optical properties were characterized through sheet resistance measurements, Hall effect, and optical transmittance in the UV–visible range. The structure and morphology were analyzed by XRD and SEM, respectively. A minimum electrical resistivity value, on the order of 7.4 × 10−3 Ω cm was obtained under the optimal deposition conditions (Ts = 425 °C), [Ga/Zn] = 2 at.%). The crystallite size ranged from 18 to 28 nm depending on the deposition temperature. An optical transparency on the order of 80%, and roughness values between 24 and 62 nm were estimated.