Imaging of the electronic states on the Si(1 1 1)1×1–As surface using a display-type photoelectron analyzer

We have measured the electronic structure of the arsenic-terminated Si(1 1 1)1×1–As surface with angle-resolved photoemission using a display-type analyzer. The analyzer records energy-resolved angular distribution patterns of the photoelectrons in a solid angle of Δθ=43° and Δϕ=360°, thereby covering the entire surface Brillouin zone at the binding energies measured here. Using this instrument we have mapped the entire two-dimensional dispersion of the lone-pair surface state, from the band maximum at Γ to the global minima at the K-points. In addition, the two-dimensional dispersions of the three upper valence bands are mapped, showing their threefold symmetry, using a photon energy of 21.2 eV. Our results are in good agreement with previous experiments and earlier quasiparticle band structure calculations.