Surface analysis and phase transition of gel-derived VO 2 thin films

Abstract

The surface composition and depth profile of vanadium dioxide thin films prepared by the sol–gel processing were investigated by using X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) techniques. It was shown from both XPS and AES results that the VO 2 phase was obtained after thermal treatment under vacuum (6.67 Pa) at 500°C for 2 h. The optical transmittance of VO 2 thin films changed greatly below and above the phase transition temperature. Doping of Li + into VO 2 thin films resulted in a reduction of the transition temperature. In contrast, Al 3+ doped VO 2 thin films had a higher transition temperature at 72°C. V 0.99P 0.01O 2 thin films had a similar phase transition temperature to that of undoped VO 2 thin films.