Vanadium dioxide phase change thin films produced by thermal oxidation of metallic vanadium

Abstract

VO2 phase change thin films are most commonly deposited by using reactive physical vapor deposition on heated substrates. In this paper, we report an alternative and more flexible method where vanadium metal films are first deposited using ordinary physical vapor deposition methods on unheated substrates, and subsequently thermally oxidized in a tube furnace to produce high quality VO2. There are several advantages to this method: it allows pre-patterning of the V films, which is significantly simpler than post-patterning VO2; and furnace oxidation is readily scalable to a large number of substrates and sizes, making this a much more manufacturable method compared to in-situ reactive methods. We have examined the physical and optical characteristics of these films using X-ray Photoelectron Spectroscopy, Atomic Force Microscopy, X-Ray Diffraction, and Ellipsometry. The film evolution from V to VO2 was observed by in-situ optical monitoring during oxidation.