High-resolution electron-energy-loss spectroscopy of vanadium and vanadium oxide thin films on TiO2(110) - (1X1) -: art. no. 165410

Vanadium thin films have been grown on the TiO2(110) rutile surface in UHV up to 4 monolayers at room temperature. These thin films have been studied by Auger electron spectroscopy and high-resolution electron-energy-loss spectroscopy (HREELS). Observation of one break in the Auger peak-to-peak ratio plotted as a function of deposition time indicates that the first monolayer formed a two-dimensional overlayer by V atoms. The growth mode of metal V at a monolayer coverage was further confirmed by HREELS results, which showed a rapid decrease of the TiO2 phonons. Subsequently, the vanadium islands were oxidized to VO2, and the obtained HREELS spectra support the growth of a rutile VO2 structure in the semiconducting phase. The intensity change and energy shift of the surface phonons are explained by consideration of the surface structure and charge transfer between VO2 overlayers and TiO2(110).