By applying k-resolved inverse photo-emission to the (√3 x √3)R30°-reconstructed 6H-SiC(00•1) face, a sharp surface state U was observed which was located at 1.10eV above the Fermi level at the centre of the surface Brillouin zone. Its band-width of 0.34eV was in good agreement with the 0.35eV predicted by first-principles calculations based upon a Si-adatom model. However, LDA calculations predicted a half-filled Σ1 state and a metallic nature for this reconstruction. Together with recent ARUPS data, the results revealed that the one-electron band Σ1 was split into two bands, giving a semiconducting surface with a reduced indirect band-gap around 2.0eV at the ¯K’ point. Many-body correlation effects could give rise, in the limit of strong localization, to this band-gap opening.

Unoccupied Surface State on the (√3 x √3) R30° of 6H-SiC(0001). J.M.Themlin, I.Forbeaux, V.Langlais, H.Belkhir, J.M.Debever: Europhysics Letters, 1997, 39[1], 61-6