TiO(001) single-crystal film formation by the incorporation of oxygen from MgO into the deposited Ti film

Abstract

The formation of a TiO͑001͒ film on MgO͑001͒ was investigated using metastable impact electron spectroscopy ͑MIES͒, ultraviolet photoelectron spectroscopy ͑He I͒, impact-collision ion scattering spectroscopy, and electron diffraction techniques. It was found that epitaxial TiO films were formed by Ti deposition on the MgO surface followed by annealing at 1000 K. The TiO film formation was related to the incorporation of oxygen from MgO into the deposited Ti film. Metallic properties of the outermost surface of the TiO film were strongly suggested by the fact that electron emission due to the autodetachment mechanism occurred in MIES, where the interaction was determined by the Coulomb interaction between temporary negative He Ϫ * ions and the hole created at the TiO surface. The work function increased from 2.6 to 5.0 eV when the TiO surface was exposed to O 2 . The electronic structure of the MgO-͑2ϫ2͒-Ti superstructure was also investigated. It is suggested that Ti is in the four-valent state at the 2ϫ2 surface.

Electronic structure of the TiO thin film on Ag(1 0 0): Angle-resolved photoemission study

“…Recently, Suzuki et al found that the TiO(1 0 0) single-crystal film can be formed by Ti deposition on MgO(1 0 0) and subsequent annealing at 1000 K [9]. They measured He I UPS spectra for the film, and observed the conduction band and the valence band at the Fermi edge and at 6.5 eV, respectively [9].…”

“…Recently, Suzuki et al found that a TiO single crystal film can be epitaxially grown on MgO(1 0 0) [8,9]. In order to explore the band structure, however, it is desirable to form the single crystal film on a conductive substrate.…”

MIES and UPS(HeI) studies on reduced TiO2(110)

“…produced by annealing in UHV to ¾1150 K. 25 Moreover, a pronounced Ti 3C 3d signal was seen from a TiO x (x ¾ 1) film on MgO. 26 A possible explanation for the absence of any Ti 3d signal in MIES may come from a recent theoretical analysis of the nature of the extra state created upon the introduction of additional charge to TiO 2 110 . 22 On the basis of firstprinciples density functional theory (DFT) calculations it was concluded that for Na adsorption the extra state is essentially localized on substrate Ti cations, with a dominant weight on those lying in the subsurface plane, just below the surface fivefold-coordinated Ti species.…”

Ion implantation and ion beam analysis of MOD deposited oxide films

“…4). Earlier reports show TiO (0 0 1) single crystal films have been deposited on MgO substrates [10].…”