Annealing Effects on W-Doped VO<sub>2</sub> Thin Films Prepared from Magnetron Sputtering

W-doped VO 2 thin films were prepared by magnetron sputtering after annealing in vacuum. The structure, morphology, infrared transmittance and phase transition were characterized by X-ray diffractometer, atomic force microscopy(AFM), infrared spectrometer (IR) and differential thermal analysis(DTA), respectively. The results show that after vacuum annealing at 500 °C for 2h, the major phase of W doped films is VO 2 . Dopant reduce the phase transition temperature of VO 2 thin films to 21.9°C.