Optical and electrical properties of thermochromic VO2 thin films on Pt layers

VO2 thin films have been successfully deposited on Pt(111)/Ti/SiO2/Si substrate by means of reactive magnetron sputtering technique. The IR reflectance of the as-prepared films exhibited a big contrast (similar to 50%) between the room temperature (25 degrees C) and high temperature (100 degrees C) owing to the fancy semiconductor-metal transition of VO2 thin film. Nevertheless, the initial resistance was very low and the transition cannot be triggered by the electrical field. Authors believe that the rather poor electrical switching behaviour was connected to the leakage current from the large grain boundaries and pores in the surface of the VO2 thin film. This study may provide insights for VO2 films grown on Pt(111)/Ti/SiO2/Si substrates and suggest that Pt layers can serve as a suitable substrate of VO2 films for optical switching devices but not for electrical switching ones.