Substrate temperature effects on the electrical properties of sputtered Al doped ZnO thin films

Al doped ZnO (AZO) thin films were deposited on glass substrate by RF magnetron sputtering system. The dependence of structural, electrical, and optical properties on the substrate temperature variations in the range of 0-400 °C was investigated. The structural results reveal that the AZO films are (0 0 2) oriented and at 400 °C a considerable crystallinity enhancement of the films is observed. With increasing the substrate temperature, the resistivity is increased by decreasing of the mobility and carrier concentration. X-ray photoelectron spectroscopy (XPS) results show that the mobility and the carrier concentration are decreased by increasing the surface bonding and decreasing the Al content, respectively. In our case, the increase in substrate temperature suppressed the incorporation of Al atoms together with the decrease of oxygen vacancy. The improvement of Al doping efficiency is a very important factor to obtain better electrical properties at high substrate temperatures.