Oxygen surplus and oxygen vacancies on the surface of epitaxial MgO layersgrown on Ag(100)

Citation
D. Peterka et al., Oxygen surplus and oxygen vacancies on the surface of epitaxial MgO layersgrown on Ag(100), SURF SCI, 431(1-3), 1999, pp. 146-155
Citations number
39
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
SURFACE SCIENCE
ISSN journal
00396028 → ACNP
Volume
431
Issue
1-3
Year of publication
1999
Pages
146 - 155
Database
ISI
SICI code
0039-6028(19990701)431:1-3<146:OSAOVO>2.0.ZU;2-4
Abstract
Growth, stoichiometry, and the generation of characteristic oxygen vacancie s of epitaxial ultrathin films of MgO grown on Ag(100) single crystals have been investigated by photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). We show that the surface of MgO is non-stoichiome tric and contains a species, identified spectroscopically as MgO2, which is strictly confined to the first monolayer. From XPS investigations of the s ubmonolayer regime of MgO, where systematic peak shifts of the O Is and Mg Is emissions similar to those measured during growth of thicker MgO layers have been found, we conclude that by thermal activation the metal-oxide int erface can be oxidized forming preferentially Mg-O-Ag bonds. By deposition of Mg layers and their incomplete evaporation, a monolayer with large oxyge n deficiency can be produced. In EELS this layer shows characteristic loss peaks at 2.1 and 3.3 eV which can be attributed to color centers due to oxy gen vacancies. (C) 1999 Elsevier Science B.V. All rights reserved.