Electronic structure of the 3C-SiC(001)2 x 1 surface studied with angle-resolved photoelectron spectroscopy

We have investigated the electronic structure of the single-domain 3C-SiC(001)2 x 1 using angle-resolved photoemission and synchrotron radiation. Two different surface-state bands are clearly identified within the bulk bandgap. The upper band has a binding energy of 1.4 eV at the center of the surface Brillouin zone and shows a weak dispersion of 0.3 eV in the <(Gamma)over bar>-(J) over bar direction, but is non-dispersive in the perpendicular direction. It has a polarization dependence suggesting a p(z) character, as expected for a Si dangling-bond state. The second band is located at 2.4 eV binding energy and is non-dispersive. The Fermi level position was determined to be at 1.7 eV above the valence-band maximum in our experiment. The weak or non-existent dispersions suggest highly localized electronic states at the surface, which are consistent with the polarized nature of the Si-C bond. The measured dispersions were compared to calculated dispersions for the proposed models for both 2 x 1 and the c(4 x 2) reconstructions, because of the expected close similarity between the 2 x 1 and the c(4 x 2) structures. Our results are in poor agreement with calculated dispersions for the simple 2x1 model with one monolayer Si termination and the alternating up-and-down-dimer (AUDD) model for c(4 x 2). The theoretical dispersions for the recently proposed missing-row-asymmetric-dimer (MRAD) model for c(4 x 2) shows somewhat better agreement, although still with significant deviations. (C) 1999 Elsevier Science B.V. All rights reserved.