Lso. Johansson et al., Electronic structure of the 6H-SiC(0001)-3 x 3 surface studied with angle-resolved inverse and direct photoemission, SURF SCI, 445(1), 2000, pp. 109-114
We have investigated the 3 x 3 reconstruction of the 6H-SiC(0001) surface w
ith angle-resolved direct and inverse photoemission (ARUPS and IPES). The s
urface was prepared by heating the sample in a Si flux and showed an excell
ent 3 x 3 LEED pattern. In the ARUPS spectra, three occupied surface states
were found at the energies 0.5 eV, 1.5 eV and 1.9 eV below E-F. In the IPE
S spectra, an unoccupied dispersionless surface state was observed at 0.5 e
V above E-F. Thereby, the reconstruction has a semiconducting character wit
h a surface bandgap of 1.0 eV. This result agrees well with recent theoreti
cal results that predict strong electron-correlation effects, leading to a
Mott-Hubbard ground state. (C) 2000 Elsevier Science B.V. All rights reserv
ed.