Optimization of microstructure and optical properties of VO2 thin film prepared by reactive sputtering

VO2 (M) thin films with good optical switching properties have been grown by reactive sputtering method. The influence of sputtering parameters on the structural and optical properties of the as-grown VO2 thin films was investigated, and the correlation between the microstructure and optical switching properties were studied. It was found that the phase transition temperature, hysteresis width, and the amplitude of the transition depend on the sputtering gas pressure, and the amplitude of the transition can reach as high as 70% with an approximately zero infrared transmission in metal state at a wavelength of 2.5 μm. The anomalous optical properties of the VO2 thin films were analyzed and discussed together with the studies of the refractive index and optical band gap.