Correlation effects at ideal SiC{0001}-(1x1) surfaces

We report on studies of the surface band structure of clean and unreconstructed 6H-SiC{0001}-(1x1) surfaces by angle-resolved photoelectron spectroscopy (ARPES). Using light induced desorption of hydrogen from the H-terminated, unreconstructed 6H-SiC{0001} surfaces we were able to prepare these highly metastable surfaces. On both Si face and C face we observe a surface band with (1x1) periodicity derived from the unsaturated surface dangling bonds. In both cases the surface band is located below the Fermi level indicating a semiconducting surface. On the (0001) surface the Si dangling bond band is located approximate to 0.8 eV above the valence-band maximum (VBM), whereas the C dangling bond band is located approximate to 0.2 eV above the VBM. The dispersion of the surface bands amount to 0.2 and 0.7 eV, respectively. The experimental observations are discussed in the light of earlier theoretical studies on the surface electronic structure of hexagonal SiC surfaces. It is suggested that the electronic properties of these surfaces are governed by strong correlation effects.