The influence of deposition temperature on the structure and optical properties of vanadium oxide films

Abstract

Thin films of various vanadium oxides, including the phase transition material vanadium dioxide, have been deposited onto sapphire substrates by reactive ion-beam sputtering. In this process, an argon ion beam sputters a vanadium target in the presence of an oxygen background. Coating chemistry, structure, surface morphology and electrical properties, together with the optical response at 3.4 μm wavelength, were studied as a function of the variation of film growth temperature Ts. Films deposited in the range 350 °C<Ts<620 °C and with a uniform argon ion beam pressure (2×10−4 Torr) and oxygen background pressure (3×10−4 Torr) show a strong dependence of growth characteristics and film properties on the deposition substrate temperature. In analogy to Thornton’s zone model for the temperature dependence of sputtered metal film growth, these metal oxide films can also be separated into different growth regions based on observed physical properties.