High visible transmittance of VO2 film prepared by DC magnetron sputtering with situ annealing

As a typical thermochromic material, Vanadium dioxide (VO2) exhibits unique optical and electrical properties. High-quality VO2 thin film was prepared by DC reactive magnetron sputtering and in situ annealing. The results show that the heating process transition temperature is 67 degrees C and the cooling process transition temperature is 49 degrees C after heating film from 25 to 90 degrees C. The low transition temperature of 58 degrees C is obtained, which is lower than 68 degrees C of VO2 crystal. In the visible region, all the transmittance between 608 and 780 nm can be greater than 40%, and the maximum visible transmittance was achieved to proximal 45%. At temperature of 90 degrees C and incident wavelength of 2.5 mu m, the large optical transmittance contrasts of 52% were obtained. Raman spectroscopy with different temperatures was used to verify the structure evolution with phase transition. Our results show that high visible transmittance and relatively low transition temperature of VO2 film on quartz substrate can be directly obtained by DC reactive magnetron sputtering and in situ annealing.