Metal sub-oxide epitaxy on SrTiO₃ via substrate interfacial oxygen scavenging

SrTiO₃ is a widely used substrate for the growth of other functional oxide thin films. However, it suffers from a relative ease in oxygen loss during thin film deposition making interfacial phenomena between SrTiO₃ and other oxides more complicated to interpret. We utilize this easy reducibility of SrTiO₃ to fabricate metal suboxides without the need to precisely control the oxygen partial pressure during growth, removing the need to worry about underoxidizing or overoxidizing the film. We have previously demonstrated this approach for the ferromagnetic semiconductor EuO. We extend this new, facile method of suboxide growth by growing epitaxial layers of oxides of the metal-insulator transition materials V₂O₃, VO₂, and NbO₂ in the absence of oxygen gas, with the oxidation state completely controlled only by temperature and metal flux. All of the oxygen needed to form the metal oxide is taken from the substrate resulting in an oxygen-deficient layer beneath the metal-oxide, forming a natural bottom electrode for the film for electrical measurements. We describe the growth process and structural characterization of the films in detail and show that this new approach is potentially useful for obtaining crystalline layers of intermediate oxidation states of metals with relative ease.