Electrical, structural and etching characteristics of ZnO:Al films prepared by rf magnetron

Al doped ZnO (AZO) films were prepared by radio frequency (rf) magnetron sputtering with varying substrate temperature, working Ar gas pressure and rf power imposed on 2-inch ZnO–Al2O3 (2 wt%) target, and their electrical and structural properties together with the corresponding etching behavior in 0.5% HCl solution were examined. The effect of rf power on the electrical and structural properties of AZO films was marginal, but in the case of working Ar gas pressure and substrate temperature, substantial variations in the electrical and structural properties were observed. The optimum electrical properties were obtained for AZO film deposited at 150 °C in lowest working pressure of 1.2 mTorr. The behavior of crater formation upon etching varied significantly depending on the structure of the film, and it was shown that the etching rate could be expressed in inversely proportional function of the crystallinity represented as (002) peak intensity. Also, for films with similar crystallinity, i.e. (002) peak intensity, dense structured film deposited at high temperature had much lower etching rate than open structured films deposited under high working Ar gas pressure.