Local band gap modulations in non-stoichiometric V2 O3 films probed by scanning tunneling spectroscopy

Abstract

Scanning tunneling microscopy and spectroscopy have been used to investigate the electronic structure of non-stoichiometric V2 O3 islands with a vanadyl termination grown on Au(111). The spectroscopic measurements reveal the correlation gap of bulk V2 O3 that varies between 0.2 and 0.75 eV for different sample preparations. In addition, gap modulations of roughly 0.2 eV are observed at different locations within the oxide islands. The changes in gap size are attributed to local deviations from the ideal V2 O3 stoichiometry in films produced at more oxidizing or reducing conditions. By evaluating the position of the Fermi level with respect to the band edges, a p -type conductance characteristic is dominantly observed for the V2 O3 islands, indicative of an efficient hole doping of the V 3d band. © 2008 The American Physical Society.