Unoccupied surface state on the (√3 × √3) R30° of 6H-SiC(0001)
Groupe de Physique des Etats Condensés, URA CNRS 783,
Faculté des Sciences de Luminy, case 901 -
F-13288 Marseille Cédex 9, France
Accepted: 30 May 1997
Applying k-resolved inverse photoemission (KRIPES) to the -reconstructed 6H-SiC(0001) face, we have observed a sharp surface state U located at above the Fermi level at the centre of the surface Brillouin zone. Its bandwidth of is in good agreement with the 0.35 eV predicted by first-principle calculations based on a Si-adatom model. However, LDA calculations predict a half-filled state and a metallic character for this reconstruction. Together with recent ARUPS data, our results reveal that the one-electron band is split into two bands, giving a semiconducting surface with a reduced indirect bandgap around 2.0 eV at the point. Many-body correlation effects may give rise, in the limit of strong localization, to this bandgap opening.
PACS: 73.20.At – Surface states, band structure, electron density of states / 71.30.+h – Metal-insulator transitions and other electronic transitions
© EDP Sciences, 1997