Electronic structure of the Si-rich 3C-SiC(001)3x2 surface

The electronic structure of the Si-rich 3C-SiC(001) surface with a single-domain 3 x 2 long-range order has been studied by angle-resolved photoemission using synchrotron radiation. By identifying the topmost bulk valence band the Fermi level position at the surface is accurately determined to be located at 2.1 eV above the valence-band maximum. Four different surface state bands are clearly identified within the bulk band gap at 1.4 +/- 0.1, 2.3 +/- 0.1, 2.9 +/- 0.1, and 3.8 +/- 0.1 eV below the Fermi level, respectively. These states show no dispersion with photon energy in normal emission and both hydrogen adsorption and Si sublimation make them disappear. Dispersions and symmetry properties of the surface states were determined in detail. All four surface state bands have unusually small dispersions throughout the surface Brillouin zone suggesting strong localization of the electron orbitals within a unit cell and a unique surface bond configuration. The origins of the surface states observed in this study are ascribed to the dangling bonds of both the Si ad-dimers and the second layer Si atoms in the 3x2 surface reconstruction. [S0163-1829(98)04136-8].