Effects of substrate temperature on the microstructure and properties of Al-doped ZnO thin films by DC magnetron sputtering from AZOY® target

Transparent conducting Al-doped ZnO (AZO) thin films were deposited on soda-lime glass substrates by DC magnetron sputtering with a sintered ceramic target, AZOY® that contains a small amount of Y₂O₃ in addition to Al2O3 and ZnO. The effect of substrate temperatures (Ts) on the structural, electrical and optical properties of the prepared AZO films was evaluated extensively. By elevating T_s, the electrical conductivity of the films could be effectively improved from 1.68 ×10-3 Ω{dot operator}cm (no substrates heating) to a minimum resistivity of 4.62×10^-4 Ω{dot operator}cm at Ts = 400°C with an average visible transmittance (400~800nm) of ~80%. It revealed that substrate heating is closely related to the crystallinity and the surface roughness of the deposited films. It is noteworthy that the transmittance in the NIR region was also improved considerably as compared to those using alloy targets by reactive magnetron sputtering and even slightly higher than those using Al-doped ZnO (1 wt.%) ceramic targets by RF sputtering.