Lattice expansion in islands stabilized by electron confinement: Ag on Si(111)-7x7

TitleLattice expansion in islands stabilized by electron confinement: Ag on Si(111)-7x7
Publication TypeJournal Article
Year of Publication2010
AuthorsUnal B, Belianinov A, Thiel PA, Tringides MC
Journal TitlePhysical Review B
Volume81
Pages085411
Date Published02/01
ISBN Number1098-0121
Accession NumberISI:000275053300109
Keywordsag/si(111), diffraction, films, growth, LOW-TEMPERATURE, photoemission, quantum-well states, surfaces, thickness, x-ray
Abstract

Ag on Si(111)-7x7 was one of the first systems where height selection of metal islands was attributed to electron confinement, i.e., stabilization of selected heights through a quantum size effect (QSE). However, it has been puzzling how the requisite electron standing waves can form, because the Fermi level E-F (along the growth [111] direction) is within the gap for bulk Ag. With detailed experiments over a wide coverage and temperature range, we show that a large increase of 12% is present in the interlayer spacing within the bilayer islands. This can shift E-F below the gap, allowing electron confinement to control height selection. This conclusion is also supported by the observation of a corrugation pattern of period 3 nm on top of the Ag islands, which is bias dependent and can only be the result of QSE-generated standing waves normal to the film.

URL<Go to ISI>://000275053300109
DOI10.1103/Physrevb.81.085411