Effect of substrate temperature on the structural, electrical and optical properties of ZnO:Ga thin films prepared by RF magnetron sputtering

Gallium doped zinc oxide (GZO) thin films were prepared by RF magnetron sputtering on glass substrates. The influence of substrate temperature (Ts) on structure, surface morphologies, chemical atomic compositions, electrical and optical properties was investigated by XRD, FE-SEM, XPS, Hall measurement and double-beam UV spectrophotometer, respectively. It is found that with increasing Ts, film crystallinity is improved, stress in the GZO films is obviously relaxed and concentrations of Ga atoms and oxygen vacancies increase. The lowest resistivity (1.41×10−3 Ω cm), and the highest figure of merit (1.94×10−2 sq Ω−1) were obtained at 300 °C. The relationship between electrical properties and Ts was clarified by analyzing the chemical element compositions and the chemical states on the surface of GZO films.