Electronic structure of the ideally H-terminated Si(111)-(1X1) surface

The valence-band electronic structure of the model system H/Si(lll)-(1x1) is measured along the main high-symmetry directions using polarization-dependent angle-resolved photoemission. This allows us to definitely identify the energy dispersion relations of the surface features. In particular, we determine the orbital symmetry of the main surface states related to the topmost Si bonds. Contrary to previous reports, we identify a remarkably sharp surface resonance (less than 260 meV wide), highly localized around the (K) over bar point at 4.3 eV from the valence-band maximum. The results of these measurements are corroborated by theoretical calculations within a tight-binding approach.