Single‐Phase Growth, Stabilization, and Electrical Properties of B Phase VO2 Films Grown on Mica by Reactive Magnetron Sputtering

Abstract

AbstractThe VO2 metastable (B) phase is of interest for applications in temperature sensing, bolometry, and Li‐ion batteries. However, single‐phase growth of thin films of this metastable phase is a challenge because vanadium oxide exhibits many polymorphs and the VO2 stable (M1) phase is usually present as a secondary phase. Additionally, the phase transition at 350 °C in the (B) phase severely narrows the processing window for achieving phase‐pure films. Here, single‐phase growth of 5‐to 50‐nm thick VO2 (B) films on muscovite, mica, by pulsed direct‐current reactive magnetron sputtering at 400 °C is demonstrated. The films are phase‐pure and exhibit a high density of 4.05 g cm−3 and low resistivity of about 50 mΩcm at 30 °C. Increasing the film thickness to 100 nm results in a V2O5‐capped VO2 (B) film with a resistivity of 8000 mΩcm. These results indicate that the stability of the VO2 (B) phase is sensitive to in situ annealing during deposition. These findings should serve as a basis to design processes to exclusively obtain phase‐pure VO2 (B) films.