Preparation and phase transition properties of nanostructured zirconium-doped vanadium oxide films by reactive magnetron sputtering

Abstract

Nanostructured zirconium (Zr)-doped vanadium oxide (VOx) films were prepared at low temperature on glass substrates by reactive direct current magnetron sputtering followed by in-situ annealing process. The effect of Zr content on the chemical composition, structure, morphology and metal–semiconductor transition properties of the deposited films was investigated systematically. It was found that Zr doping significantly reduced the grain size of VOx films due to increased density of nucleation centers, but was found almost not to influence the structure and the +4 valence vanadium concentration. Interestingly, the hysteresis width was hugely modulated from 30.0 to 5.8°C while the phase transition temperature upon cooling increases from 42.0 to 56.7°C as the Zr/V atomic ratio in the deposited film increases from 0 to 13.9%. However, the phase transition temperature upon heating initially decreases with Zr/V atomic ratio, attains a minimum of 53.8°C at a Zr/V atomic ratio of 8.5%, and then increases with increase in Zr/V atomic ratio. The decrease in hysteresis width with the increase in Zr contents can be attributed to the increased density of nucleation defects introduced by Zr doping. This work shows that Zr doping can effectively regulate the morphology and the phase transition characteristics of VOx films.