Interface effects in the electronic structure of TiO_2 deposited on MgO, A1_2O_3 and SiO_2 substrates

摘要

We report the Ti 2p X-ray absorption (XAS) and resonant photoemission (RPES) spectra of one equivalent TiO_2 monolayer grown on MgO, Al_2O_3 and SiO_2 substrates. The Ti 2p XAS spectra of these systems were compared to atomic multiplet calculations projected in different octahedral crystal fields. The comparison indicates that the crystal field splitting and the Ti-0 hybridization decrease along the MgO, Al_2O_3 and SiO_2 series. The analysis of the RPES spectra provides the Ti 3d contributions to the valence band in these systems. These were compared to configuration interaction calculations of a TiO_6 cluster for different Ti 3d-O 2p hybridizations. The Ti 3d states in the valence band shift to lower binding energies along the MgO, Al_2O_3 and SiO_2 series. These effects are attributed to changes in the electronic structure at the interface, which, in turn, are related to the formation of cross-linking Ti-O-M (M = Mg, Al, and Si) bonds.