Structural studies of epitaxial ultrathin oxide films and nanoclusters by means of angle-scanned photoelectron diffraction (XPD)

Selected examples of the application of angle-scanned x-ray photoelectron diffraction (XPD) to structural studies of epitaxial oxide ultrathin films and nanoclusters deposited either on metal or on oxide single-crystalline substrates are briefly reviewed. A short introduction discusses the preparative strategies adopted in order to grow the desired oxide systems, as well as the basic features of the XPD technique which are relevant to the field of oxide epitaxy. Synthesis routes include both e-beam metal evaporation and oxidation and a modification of metal-organic chemical vapour deposition to suit ultra-high-vacuum conditions. These introductory remarks are followed by an overview of some systems that have been investigated in our laboratory. The discussion is particularly aimed at highlighting the peculiar capabilities and strengths of photoelectron diffraction applied to - even short-range-ordered - oxide epitaxial systems. Oxide overlayers obtained by means of reactive deposition or post-oxidation comprise various vanadium oxide phases grown on rutile TiO2(110), while metalcarbonyl precursor decomposition in an oxygen atmosphere as a source of oxide ultrathin films is illustrated through the cases of RuO2/TiO2(110) from Ru3(CO)12 and MnO/Pt(111) from Mn2(CO)10. Finally, some remarks are made on recent developments and future perspectives in the field of synchrotron-radiation-based implementations of photoelectron diffraction and holography.