Reactive evaporation of anomalous blue VO2

Abstract

Thin films of vanadium dioxide exhibit a thermally induced semiconductor-to-metal phase transition near 67°C. In most deposition conditions, the transition is accompanied by large changes in optical properties at infrared wavelengths but with only slight visible contrast. Recently, reactive evaporation at high temperatures and in stringent process conditions of so-called blue VO2 has been reported.1 These films show a striking blue-to-red transition in transmitted light. In this paper a new technique for thin-film growth of anomalous vanadium dioxide is presented. The primary steps in the process are the reactive evaporation of vanadium oxide at ambient temperature followed by anneal in flowing oxygen. Optical and microstructural data for material deposited on sapphire and fused quartz substrates are compared to standard vanadium dioxide.