Tuning phase transition temperature of VO₂ thin films with annealing O₂ pressure

Phase transition temperature is very important for application of VO₂ films as "smart window", which can help control the room temperature intelligently. It used to be tuned by doping which is complicated and expensive. A simple new way to tune the optical phase transition temperature of VO₂ films was proposed by only controlling the pressure of oxygen during the annealing process. V films were deposited on glass by a magnetron sputtering coating system and then annealed in appropriate oxygen atmosphere to form the VO₂ films. The infrared transmission change (at 2400 nm) is as high as 58% for the VO₂ thin film on glass substrate, which is very good for tuning infrared radiation and energy saving as smart windows. The phase transition temperature of films can be easily tuned from intrinsic temperature of 68 ° to 44.7 ° and 40.2° on glass and sapphire by annealing oxygen pressure, respectively.