Growth of platinum on TiO2- and SrO-terminated SrTiO3(100)

Growth by molecular-beam epitaxy of platinum on TiO2-terminated and SrO-terminated (100) SrTiO3 (STO) single-crystal substrates was investigated. TiO2-terminated surfaces were produced by wet chemical etching and SrO-terminated surfaces by reactive molecular-beam epitaxy of SrO on TiO2-terminated substrates. Growth of both the platinum and SrO layers was monitored in vacuum by reflection high-energy electron diffraction and Auger electron spectroscopy, and the resulting films were characterized by X-ray diffraction, atomic force microscopy, and cross-sectional conventional and high-resolution transmission electron microscopies. The orientation of the platinum films was found to be strongly dependent on the surface termination: cube-on-cube Pt(100) was predominant for the TiO2-terminated surfaces, while the SrO-terminated showed a mixture of Pt(100) and Pt(111). The change in film orientation observed is attributed to a smaller degree of bonding across the interface for the SrO-terminated surface.