Well-Known "Surface State" on Si(111)2×1 Identified as a Bulk Contribution

Using polarization-dependent angle-resolved photoemission we show that two dominating structures in the photoemission spectra are due to direct transitions from the uppermost two valence bands in silicon. The final-state band for these transitions at photon energies 10.2-21.2 eV is found to have free-electron-like dispersion. Our results imply that that threefold-symmetry emission often assigned to back-bond surface states on Si(111)2×{}1 is really due to bulk photoemission.