Al-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.