Band gap of epitaxial in-plane-dimerized single-phase NbO2films

Abstract

We demonstrate the epitaxial growth of high quality crystalline phase-pure NbO2 films on various oxide substrates using molecular beam epitaxy. Using a combination of reflection high-energy electron diffraction and x-ray diffraction we show that the films grow with the pseudo-rutile (100) orientation out of plane. The band gap of the NbO2 films is determined to be at least 1.0 eV using a combination of x-ray photoelectron spectroscopy and inverse photoelectron spectroscopy, in conjunction with hybrid density functional calculations of the density of states.