Al3+-doped vanadium dioxide thin films deposited by PLD

Thin films of vanadium dioxide (VO2) and Al3+-doped VO2 were deposited on silicon and glass substrates using pulsed laser deposition (PLD). Optimized processing conditions were determined for depositing pure VO2 with monoclinic phase by laser ablation of a V2O5 target. Al3+-doping levels in the VO2 films were varied by altering the relative laser ablation time on the Al2O3 and V2O5 targets. The change in electrical conductivity with temperature in the semiconductor to metallic phase transition was measured for pure VO2 and Al3+-doped VO2 films. Doping the VO2 films with Al3+ lowered the transition temperature directly on increasing the Al3+ content from 67 °C for the pure VO2 films to 40 °C at 10% Al3+. The magnitude of the resistance change from semiconductor to metallic states also decreased with increase in Al3+ doping. The results imply that Al3+-doped VO2 films could be a good candidate for energy-efficient “smart window” coatings used for architecture applications.