Unoccupied Surface States Of The C(2x2)-Reconstructed 3c-Sic(001) Surface

We have investigated the c(2x2)-reconstructed 3C-SiC(001) surface using angle-resolved inverse photoemission. Four unoccupied surface resonances are observed. The surface band dispersion E(k(parallel to)) is recorded in the high-symmetry directions (Gamma M) over bar and (Gamma S) over bar respectively. Two experimentally determined surface structures correspond to the antibonding pi(1)* and pi(2)* surface bands obtained by local-density approximation calculations for the bridging dimer model of the c(2x2)-reconstructed surface. The theoretically alternatively discussed staggered dimer model for the c(2x2) reconstruction shows the antibonding pi* surface band 0.5 eV below the conduction-band minimum at the (Gamma) over bar point. This surface band with a calculated upward dispersion of 1.5 eV in (Gamma S) over bar and (Gamma M) over bar directions, respectively, is not observed in the present study. The present work clearly supports the bridging dimer model for the c(2x2)-reconstructed 3C-SiC(001) surface.