Effect of sputtering conditions on growth and properties of ZnO:Al films

Abstract

Al-doped zinc oxide (AZO) films were deposited on glass substrates by mid-frequency magnetron sputtering. The effects of substrate rotation speed and target–substrate distance on the electrical, optical properties and microstructure and crystal structures of the resulting films were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), spectrophotometer and Hall-effect measurement system, respectively. XRD results show that all AZO films exhibit a strong preferred c-axis orientation. However, the crystallinity of films decreases with the increase of substrate rotation speed, accompanying with the unbalanced grains grows. For the films prepared at different target–substrate distances, the uniform microstructure and morphology are observed. The highest carrier concentration of 5.9×1020 cm−3 and Hall mobility of 13.1 cm2/(V·s) are obtained at substrate rotation speed of 0 and target–substrate distance of 7 cm. The results indicate that the structure and performances of the AZO films are strongly affected by substrate rotation speed.