Epitaxial niobium dioxide thin films by reactive-biased target ion beam deposition

Abstract

Epitaxial NbO2 thin films were synthesized on Al2O3 (0001) substrates via reactive bias target ion beam deposition. X-ray diffraction and Raman spectra were used to confirm the tetragonal phase of pure NbO2. Through XPS, it was found that there was a ∼1.3 nm thick Nb2O5 layer on the surface and the bulk of the thin film was NbO2. The epitaxial relationship between the NbO2 film and the substrate was determined. Electrical transport measurement was measured up to 400 K, and the conduction mechanism was discussed.