Optical and electrical characterization of gradient AZO thin film by magnetron sputtering

Gradient Al-doped ZnO (AZO) thin films were deposited by magnetron sputtering. The effects of Al concentration gradient on the structure, optical and electrical properties of gradient AZO films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, four probe tester and UV–visible spectrophotometer. Results show that all of the gradient AZO films have the hexagonal wurtzite structure with c axis preferential orientation and no other secondary phase exits. With the increase of the Al concentration gradient, the resistivity of AZO thin films deteriorates. The resistivity was least, 1.18 × 10−2 Ω cm, for magnetron sputtering-gradient AZO films at 0.02 % nm−1 Al concentration gradient. The average transmittance of the gradient AZO thin films on the glasses in the band of visible light is about 80 %.