Electronic properties of clean unreconstructed 6H-SiC(0001) surfaces studied by angle resolved photoelectron spectroscopy

摘要

The properties of the clean and unreconstructed 6H-SiC(0001) and 6H-SiC(0001) surfaces were investigated by means of angleresolved photoelectron spectroscopy (ARPES). These highly metastable surfaces were prepared by exposing hydrogen terminated surfaces to a high flux of synchrotron radiation. On both surfaces we find a band of surface states with 1 x 1 periodicity assigned to unsaturated Si and C dangling bonds located at 0.8 eV and 0.2 eV above the valence band maximum, respectively. Both states are located below the Fermi level. The dispersion of the surface bands amounts to 0.2 eV for the Si derived band and 0.7 eV for C derived band. It is suggested that the electronic properties of these surfaces are governed by strong correlation effects (Mott-Hubbard metal insulator transition). The results for the (0001) surface are directly compared to Si-rich (root 3 x root 3)R30 degrees reconstructed surface. Distinct differences in electronic structure of the (root 3 x root 3)R30 degrees and 1 x 1 surfaces are observed. (c) 2006 Elsevier B.V. All rights reserved.