Role of Oxygen Deposition Pressure in the Formation of Ti Defect States in TiO(001) Anatase Thin Films.

We report the study of anatase TiO(001)-oriented thin films grown by pulsed laser deposition on LaAlO(001). A combination of in situ and ex situ methods has been used to address both the origin of the Ti-localized states and their relationship with the structural and electronic properties on the surface and the subsurface. Localized in-gap states are analyzed using resonant X-ray photoelectron spectroscopy and are related to the Ti electronic configuration, homogeneously distributed over the entire film thickness. We find that an increase in the oxygen pressure corresponds to an increase in Ti only in a well-defined range of deposition pressure; outside this range, Ti and the strength of the in-gap states are reduced.