Many-body effects in the (111)-silicon dangling-bond surface states

The many-body properties of the strongly correlated two-dimensional dangling bond electron gas of a (1 × 1)-Si surface have been analysed by means of an accurate solution of a Hubbard Hamiltonian. The experimental similarity between the (1 × 1) and the (7 × 7) faces allows us to extend our analysis to the latter surface. A peak appearing near the Fermi energy for the (7 × 7) face at low temperatures is related to a kind of “Kondo-peak” for the Hubbard Hamiltonian. Photoemission spectra for the (1 × 1) surface of highly doped Si can be understood in terms of our model.