Electrical and optical properties of Al-doped ZnO–SnO2 thin films deposited by RF magnetron sputtering

Aluminum-doped ZnO–SnO2 (ZTO) films were deposited by RF magnetron sputtering using a Zn2SnO4 target at 400 °C under Ar gas pressure of 2.0 Pa. The Al doping was carried out by placing Al sheets on the Zn2SnO4 target and the inclusion of Al was observed to increase to 5.3 at.%. The transmittance of Al-doped ZTO films decreased in the short wavelength region with increasing Al concentration. Al doping had no observable effect on the refractive index, but the electrical properties were remarkably affected. The conductivity exponentially decreased from 3.2 × 10 to 2.3 × 10− 4 S cm− 1 as the Al concentration increased from 0.0 to 5.3 at.%. The Hall mobility and free carrier density also decreased with increasing Al concentration.