Electronic structure and nature of the bonding at the Cu(110)+c(2x2)-Si surface alloy

The electronic structure of the Cu(110) + c(2 x 2)-Si surface alloy has bee n studied experimentally by synchrotron radiation photoemission spectroscop y. We have recorded normal emission photoemission spectra as a function of the photon energy, Si coverage and angle of incidence of the polarized ligh t in order to identify the electronic features induced in the Cu valence ba nd by the presence at the surface of an ordered Si-Cu bidimensional layer. Two main dispersionless bands in the direction perpendicular to the surface and centered around -3 and -1 eV of binding energy are the most characteri stic electronic features of the system. Most of the details in the photoemi ssion spectra are well reproduced by a local density of states calculation employing the Extended Huckel Theory. These results suggest that the electr onic states from the surface alloy are mainly originated by an in-plane hyb ridization of the Cu 3d electrons from the outermost layer with the Si 3p e lectrons. (C) 2000 Elsevier Science B.V. All rights reserved.