Experimental surface-state band structure of the Si(111)-(√3 × √3 )-Au surface

The surface-state band structure of the Si(111)-({}3 ×{} {}3 )-Au surface has been studied in detail with polarization-dependent angle-resolved photoelectron spectroscopy. In the {Γ}{}-M{} direction three surface states are observed, while in the {Γ}{}-K{}-M{} direction only two surface states are identified. The dispersions (initial energy versus k?) of these surface states have been mapped out. A nondispersive surface state, close to the Fermi level, is tentatively assigned to boundaries between {}3 ×{} {}3 domains, which have recently been observed in scanning-tunneling-microscopy studies. It is suggested that the Fermi-level position at the surface is determined by this surface state. Comparisons with the surface electronic structure of the Si(111)-({}3 ×{} {}3 )-Ag surface show mainly differences, indicating that the Au- and Ag-induced {}3 ×{} {}3 reconstructions have different atomic structures.