Surface and interface chemical composition of thin epitaxial SrTiO ₃ and BaTiO ₃ films: Photoemission investigation

The effect of surface preparation on chemical and electronic film, and interface properties were studied using SrTiO ₃ and BaTiO ₃ films epitaxially grown on Si(100) substrates. It was found that while the valence band maximum shifts by more that 2 eV, the oxide core level shifts by less than 0.6 eV, depending on the surface treatment. It was also found that extremely careful cleaning procedures should be applied since the surface composition and film morphology are of paramount importance in determining the electronic structure of the crystalline oxides. It was shown that the interfaces between SrTiO ₃ and BaTiO ₃ and Si, which were unstable at annealing temperatures, required thorough cleaning and ordering.