Atomic and Electronic-Band Structures of Anomalous Carbon Dimers on3C−SiC(001)−c(2×2)

The atomic structure of the $c(2\times 2)$ reconstruction of the $C$-terminated $3C-\mathrm{SiC}\left(001\right)$ surface was unambiguously determined by scanning tunneling microscopy and surface-core-level-resolved photoelectron diffraction studies. This surface is found to uniquely and uniformly consist of anomalous bridge-bonded C dimers with a C-C bond length of 1.22 Å. Furthermore, an extensive angle-resolved photoemission study clearly identifies two occupied π state bands due to the surface-normal and -parallel π orbitals of the triple-bonded C dimers. This provides an electronic explanation of the stability of this unique surface reconstruction.