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

The formation of a TiO(001) film on MgO(001) was investigated using metasta ble impact electron spectroscopy (MIES), ultraviolet photoelectron spectros copy (Hel), impact-collision ion scattering spectroscopy, and electron diff raction 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 fil m formation was related to the incorporation of oxygen from MgO into the de posited Ti film. Metallic properties of the outermost surface of the TiO fi lm were strongly suggested by the fact that electron emission due to the au todetachment mechanism occurred in MIES, where the interaction was determin ed by the Coulomb interaction between temporary negative He-* 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 t he MgO-(2x2)-Ti superstructure was also investigated. It is suggested that Ti is in the four-valent state at the 2x2 surface.