Spectral identification scheme for epitaxially grown single-phase niobium dioxide

Tobias Hadamek, Agham B. Posadas, Ajit Dhamdhere, David Smith, Alexander A. Demkov

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


This publication describes how to distinguish under-oxidized and over-oxidized phases of the metal-insulator transition material NbO2 by employing a combination of the Nb 3d and O 1s core-level and valence-band spectra. Niobium oxides (NbOx) are grown under various conditions by molecular beam epitaxy on several different substrates, mostly (111)-oriented strontium titanate (SrTiO3), in order to obtain phase-pure NbO2. The films are characterized by in situ reflection high-energy electron diffraction, X-ray diffraction, and transmission electron microscopy to determine crystallinity, lattice constants, and epitaxial relationships. Niobium metal oxidation states and film stoichiometry are determined with in situ X-ray photoelectron spectroscopy. Asymmetric Nb 3d core-level spectral components are observed in phase-pure NbO2, with a binding energy for Nb 3d5/2 of 206 eV. The effect of substrate type, growth temperature, and oxygen pressure on the film composition is also described.

Original languageEnglish (US)
Article number095308
JournalJournal of Applied Physics
Issue number9
StatePublished - Mar 7 2016

ASJC Scopus subject areas

  • General Physics and Astronomy


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