ELECTRONIC-STRUCTURE OF THE ARSENIC-PASSIVATED SI(111) SURFACE

An empirical tight-binding (ETB) approach combined with a Green's-func tion (GF) method has been employed to investigate the electronic struc ture of the Si(111) and arsenic-passivated Si(111) surfaces. An accura te silicon band structure has first been developed keeping up to secon d-nearest-neighbor terms in the Hamiltonian. The ETB-GF approach has a llowed the calculation of the local density of states (LDOS) at variou s atomic layers of the semi-infinite samples. It has also been possibl e to calculate the contribution of the individual atomic orbitals to t he LDOS. The results obtained for the arsenic-passivated Si surface pr ovide the position and strength of localized surface states as well as the density of the bulk states in the valence band, the band gap, and the conduction band. The calculated localized states reproduce the ex isting experimental data and other partial calculations. Furthermore, this calculation predicts a localized state in the conduction band, wh ich has so far not been studied experimentally.