Surface oxidation of vanadium dioxide films prepared by radio frequency magnetron sputtering

This paper reports that the thermochromic vanadium dioxide filmswere deposited on various transparent substrates by radio frequencymagnetron sputtering, and then aged under circumstance for years.Samples were characterized with several different techniques such asx-ray diffraction, x-ray photoelectron spectroscopy, and Raman, whenthey were fresh from sputter chamber and aged after years,respectively, in order to determine their structure and composition.It finds that a small amount of sodium occurred on the surface ofvanadium dioxide films, which was probably due to sodium iondiffusion from soda-lime glass when sputtering was performed at highsubstrate temperature. It also finds that aging for yearssignificantly affected the nonstoichiometry of vanadium dioxidefilms, thus inducing much change in Raman modes.