Unambiguous identification of the Si 2p surface core-level shifts in Sb and Ag terminated silicon surfaces studied with high energy resolution photoemission

We have performed core-level photoemission measurements on Sb/Si(111) ?3×?3, Sb/Si(100) 2×1, Sb/Si(110) 2×3 and Ag/Si(111) ?3×?3R(30°) surfaces with the improved energy resolution of the ‘VUV Photoemission’ beamline at the ELETTRA third generation SR facility. In the case of antimony on Si(111), Si(100) and Si(110) our results show the presence of a strong Si2p interfacial component (S) whose shift with respect to the bulk peak is +130, +200 and +240 meV, respectively. A small component (C) was present in all surfaces on the high kinetic energy side. In the case of Ag/Si(111) ?3×?3R(30°) the Si 2p spectrum shows the presence of three components in addition to the bulk peak, shifted respectively by +450, +250, ?220 meV. We assign the surface components to charge transfer and to the reconstruction structural elements.