Effects of substrate temperature on crystallinity and electrical properties of Ga-doped ZnO films prepared on glass substrate by ion-plating method using DC arc discharge

The effects of substrate temperature, Ts, on the crystallinity and the electrical properties of Ga-doped ZnO films (GZO) with a thickness of 200 nm were investigated. GZO films were prepared on glass substrates at various Ts in the range from 150 to 400 °C by ion-plating method with DC arc discharge. X-ray diffraction analysis reveals that GZO film prepared at 250 °C shows the preferential orientation of c-axis and the highest crystallinity. Williamson–Hall analysis indicates that the crystallite size of GZO films remains nearly constant with increasing Ts up to 300 °C, and then, with further increasing Ts, decreases gradually. The Ga concentration in the films, estimated by secondary ion mass spectroscopy and X-ray fluorescence analyses, increases monotonically with increasing Ts above 250 °C. Hall effect measurements show that resistivity decreases slightly with increasing Ts up to 250 °C, leading to the lowest resistivity of 2.1 × 10− 4 Ω cm at 250 °C, and then exhibits a gradual increase with further increasing Ts.