Abstract
We have investigated the electronic structure of the single-domain 3C–SiC(001)2×1 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 Γ̄–J̄ direction, but is non-dispersive in the perpendicular direction. It has a polarization dependence suggesting a pz 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 SiC bond. The measured dispersions were compared to calculated dispersions for the proposed models for both the 2×1 and the c(4×2) reconstructions, because of the expected close similarity between the 2×1 and the c(4×2) structures. Our results are in poor agreement with calculated dispersions for the simple 2×1 model with one monolayer Si termination and the alternating up-and-down-dimer (AUDD) model for c(4×2). The theoretical dispersions for the recently proposed missing-row-asymmetric-dimer (MRAD) model for c(4×2) shows somewhat better agreement, although still with significant deviations.
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