The adhesion properties of the Ag/alpha-Al2O3(0001) interface: an ab initio study
2002 (English)In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 513, no 2, 343-358 p.Article in journal (Refereed) Published
Ab initio computer simulations of the atomic and electronic structure of the Ag/alpha-Al2O3(0 0 0 1) (corundum) interface have been performed for a periodic two-dimensional slab model using the Hartree-Fock method and a posteriori electron correlation corrections. We have considered both Al- and O-terminated corundum substrate surfaces. The dependence of the adhesion energy on the interfacial distance has been analyzed for the two most favorable Ag adsorption positions over corundum and for two different metal coverages (a 1/3 monolayer (NIL) of the Ag(l 1 1) crystallographic plane and a full Ag(I 1 1) monolayer). The two different terminations (Al- and O-) give rise to qualitatively different results. The former case corresponds to the most stable termination of the pure corundum (0 0 0 1) substrate where small adhesion energies per Ag atom (0.15-0.25 eV for I ML and 0.40-0.55 eV for 1/3 NIL) are accompanied by minor interfacial charge transfer, indicating physisorption, which may be explained by a weak atomic polarization. In contrast, for O-terminated corundum, substantial adhesion energies (3-5 eV per Ag atom at I ML coverage and 6-11 eV for 1/3 ML) combined with noticeable charge transfer from silver atoms towards the substrate (0.5e to 0.9e) are clear indications of a strong interfacial ion bonding. For both terminations, the observed difference in Ag adhesion energies for 1/3 NIL and I NIL coverages arises from a transition from directed Ag-O bonding towards a more delocalized electron density distribution in the complete monolayer. The results of our calculations are compared with available experimental studies and theoretical simulations for various Me/Al2O3 interfaces.
Place, publisher, year, edition, pages
2002. Vol. 513, no 2, 343-358 p.
metal-semiconductor interfaces, silver, physical adsorption, adhesion, aluminum oxide, single crystal surfaces, metallic films, ab initio quantum chemical methods and calculations, computer simulations, first-principles calculations, electronic-structure, alpha-al2o3(0001) surface, sapphire alpha-al2o3, periodic-systems, aluminum-oxide, metal adhesion, hartree-fock, 0001 surface, energy
IdentifiersURN: urn:nbn:se:kth:diva-21720ISI: 000176853100016OAI: oai:DiVA.org:kth-21720DiVA: diva2:340418
QC 201005252010-08-102010-08-10Bibliographically approved