Effects of substrate temperature on the properties of facing-target sputtered Al-doped ZnO films

ZnO:Al films (Al 2.5 wt%) were deposited using a DC facing targets magnetron sputtering via two ZnO targets mixed with Al2O3. The structural, electrical and optical properties of the deposited films were strongly influenced by substrate temperature. Films with better texture, higher transmission, lower resistivity and larger carrier concentration were obtained for the samples fabricated at higher substrate temperature. The optimal condition for deposition of ZnO:Al film with the lowest resistivity of 3.18×10−4 Ω cm, the highest carrier concentration of 4.58×1020 cm−3, and a transmission toward 85% in the visible range was obtained at 200 °C. This film proposes a promising future for the application of the practical window and contact layers for solar cells.