Origin of electrical property distribution on the surface of ZnO:Al films prepared by magnetron sputtering

Abstract

The origin of electrical property distribution on the substrate surface of Al-doped ZnO (AZO) films prepared by magnetron sputtering is reported. When the films were prepared on substrates at the same temperature with the same deposition rate under optimized sputter deposition and target preparation conditions, the minimum obtained resistivity found in AZO films prepared by either dc or rf magnetron sputtering was roughly the same: 3–4×10−4 Ω cm on substrates at 200 °C. However, the AZO films prepared by dc sputtering exhibited a larger increase of resistivity at locations on the substrate corresponding to the target erosion area than that found in films prepared by rf sputtering. The resistivity distribution of AZO films prepared by rf magnetron sputtering under an applied external magnetic field which focused the rf plasma was similar to that of films prepared by dc magnetron sputtering. Thus, the electrical property distribution found in films prepared by either dc or rf magnetron sputtering is mainly related to the activity and the amount of oxygen reaching the substrate surface as well as its spatial distribution.