Oxidation of barium on the surface of nanothick chromium oxide films grown on the (110) molybdenum substrate

Auger electron spectroscopy and work function measurements were used to investigate adsorption of barium onto the surface of nanothick chromium oxide films grown on the (110) molybdenum substrate. We prepared smooth 3-monolayers (ML) thick pseudomorphic chromium oxide films and rough 2-3 ML chromium oxide films carrying three-dimensional oxide nanoparticles (the Stranski-Krastanov (SK) surface morphology). The interaction of barium with chromium oxide films of both types was Found to lead to barium oxide formation and partial reduction of chromium oxide to chromium. When barium was deposited onto a 3 ML pseudomorphic chromium oxide film, the barium oxidation at room temperature was restricted to formation of only one monolayer of barium oxide. However, in the case of barium adsorption on chromium oxide film with the SK type surface morphology, the oxidation encompassed 3 monolayers of barium. A strong effect of metal substrate-oxide film interface on the oxidation ability of nanothick oxide films was revealed. These results showed possibilities of tailoring surface properties of the barium oxide films by variation of their thickness and by substrate-film interface modification.