Stoichiometry and morphology of MgO films grown reactively on Ag 100/1

The stoichiometry and the morphology of MgO adlayers epitaxially grown on Ag 100.are studied by means of X-ray photoelectron spectroscopy XPS.and high-resolution spot profile analysis low-energy electron diffraction SPA-LEED.. For comparison, Mg deposited at 200 K is oxidized after and during growth, respectively. The post-oxidized film is dominated by stoichiometric MgO but shows also non-stoichiometric species. Annealing the film to 700 K reduces the latter components. Strong differences have been found for the epitaxy of both kinds of MgO films, depending on the preparation condition. The post-oxidized film shows a clear diffraction pattern with 12-fold symmetry due to MgO 100.grains in three rotational orientations only after annealing to 700 K. Depositing and oxidizing simultaneously the Mg the oxide film shows a better film quality no metallic Mg, a small MgO2 fraction.and epitaxy with 1=1 already at 200 K. q1999 Elsevier Science B.V. All rights reserved.