Structural, electrical and optical properties of Al-doped ZnO thin films prepared by filtered cathodic vacuum arc technique

Highly conductive and transparent aluminum-doped zinc oxide (ZnO:Al) thin films have been prepared using the filtered cathodic vacuum arc technique at relatively low temperatures. The properties of ZnO:Al films under the influence of substrate temperature were investigated. It was found that the optical, electrical and structural properties of the films depended directly on substrate temperature during deposition. ZnO:Al films exhibited c-axis oriented crystal growth. The ZnO:Al films were prepared using Zn-Al alloy targets with various Al content. The lowest resistivity of 8×10-4Ωcm was obtained for the Al-doped (5 at%) film prepared at a substrate temperature of 150°C. The optical absorption edge was found to shift to the shorter wavelength with a reduction in substrate temperature, and it was found that doping with Al had the effect of broadening the optical band gap, with both cases being attributed to the Burstein-Moss shift.