Effect of sputtering power on the properties of ZnO:Ga transparent conductive oxide films deposited by pulsed DC magnetron sputtering with a rotating cylindrical target

Effect of sputtering power on the properties of ZnO:Ga (GZO) transparent conductive oxide (TCO) films was investigated on the films deposited by pulsed DC magnetron sputtering with a rotating cylindrical target. At lower sputtering power up to 2.0 kW, the films showed flat surfaces with some pit-like structures. However, films morphology deteriorated with higher sputtering power up to 3.5 kW as reflected in the rough porous surfaces. Microstructures of the films evolved into the uniformly shaped columnar grains well aligned with the c-axis with the increasing sputtering power up to 2.0 kW, but further increasing the sputtering power caused the irregularity of the grain shapes and their orientations. Accordingly, the film deposited at 2.0 kW showed the lowest electrical resistivity of 4.89 × 10−4 Ω cm achieved through the highest Hall mobility of 25.9 cm2 V−1 s−1. All the GZO films in this study showed the optical transmittances higher than 80%.