Effects of sputtering pressure on properties of Al doped ZnO thin films dynamically deposited by rf magnetron sputtering

Aluminium doped zinc oxide (AZO) films were dynamically deposited by rf magnetron sputtering under various sputtering pressures in the range of 0·3-2·0 Pa. The effect of the Ar sputtering pressure on the structural, electrical and optical properties of the AZO films was systematically investigated by X-ray diffractometry, scanning electron microscope, four-point probe measurement and UV-vis spectrophotometer. As the sputtering pressures decrease, the crystallite sizes of the films became larger, while their deposition rate turns higher. Under the condition of lower sputtering pressures, a decrease in the resistivity was observed due to an increase in carrier concentration. The AZO film deposited at 0·5 Pa in the dynamic mode has shown the lowest resistivity of 9·5 × 10 ^-4 Ω cm. This work was performed in a dynamic deposition system in order to produce a large area of AZO films, which is more important in practical fields to improve productivity.