A density functional theory study of the atomic and electronic structures of 3C-SiC(1 1 1)-(23×23)-R30° surface reconstruction

The electronic structures of SiC(1 1 1)-(23×23)-R30° surface reconstruction are studied using the discrete variational method in the framework of local density formalism. The calculation results suggest that the absence of quarter amount of Si atoms on the topmost layer of the Si-terminated surface is energetically favorable. The optimal geometry determined by the energy minimization includes the vertical and lateral displacements of the surface Si atoms and the subsurface C atoms. The calculated electronic structures show some features in the SiC band gap, which do not exist for a perfect Si-terminated SiC surface. The partial densities of states for different Si and C atoms are derived, from which the variation of the patterns and periodicities observed in the scanning tunneling microscopic experiment under different bias voltages can be explained.