Growth of Al doped ZnO thin films prepared with a powdery sputter target for low cost applications

Aluminum doped zinc oxide (AZO) films were prepared by r.f. magnetron sputtering. In the present work, ZnO powder with Al₂O₃ content of 2.5 wt% was used as a sputter target in order to reduce the cost and time of the film formation processes. The influence of the sputtering power on the structural, electrical, and optical properties of the AZO films was investigated. The electrical resistivity was decreased when the films were deposited at a higher power. The minimum value of 7.5×10^-4 ω-cm was obtained at the sputtering power of 195 Watt. The optical transmittance of AZO films exhibits a strong dependence on the sputter power. The optical transmittance of the film was improved with increasing the r.f. power and the absorption edge shifted to a shorter wavelength, suggesting that the optical band gap increased.