VO2 film with small hysteresis width and low transition temperature

In this paper, we investigate the vanadium dioxide (VO2) film as optical switching deposited on Al doped zinc oxide (AZO) glass substrates by DC reactive magnetron sputtering. Field-emission scanning electron microscopy reveal that the deposited VO2 film consists of irregular nanostructured grains. The optical tests by means of UV-visible spectrophotometer show that the deposited VO2 film exhibits excellent optical switching properties with a very small phase-transition hysteresis width of 2.9 degrees C as well as a low phase-transition temperature of about 48 degrees C. More interesting, the semiconductor-to-metal transition is readily induced by Joule heat produced by electrical current through the AZO conductive layer, which is more efficient and convenient compared with the traditional heating of the sample by heating plate. This work is of crucial importance for potential applications of VO2 film in compact optical switching devices.