Surface Oxidation State Variations and Insulator-Metal Transition Modulations in Vanadium Oxides with Pulsed Hydrogen Plasma

Surface often determines the formation and function of nanoscale thin films and nanomaterials. In correlated vanadium oxides, oxidation states and stoichiometry play important roles in regulating reversible insulator-metal transition (IMT) behaviors. This study presents the surface oxidation state reductions and IMT modulations in vanadium oxides. Oxidation states of vanadium in the surface layer are changed in the nanostructures of vanadium oxides through pulsed hydrogen plasma (PHP). The thickness-dependent variations are also observed with Raman and X-ray photoelectron spectroscopy (XPS), and verified in vanadium oxides with different oxidation states. Obvious modulations on IMT behaviors are then demonstrated and related to such variation of surface oxidation states in the VO2 thin film and nanobeam. It is expected that such surface manipulations are beneficial to a better understanding of the IMT in correlated vanadium oxides and the fabrication of advanced functional electronic and photoelectronic devices.