The atomic structure of the β-SiC(100)-c(2 x 2) surface was analyzed using dynamical calculations of low-energy electron-diffraction intensities. The c(2 x 2) surface was prepared in ultrahigh vacuum by two different methods. The first utilized the removal of surface silicon by high-temperature annealing in ultrahigh vacuum. The second route utilized the deposition of surface carbon by exposing the stoichiometric (2 x 1) surface at 1125K to C2H4. The results showed that both methods produced a surface terminated with C2 groups in staggered silicon bridge sites. Weak silicon dimer bonds were found in the second atomic layer of the c(2 x 2) surface produced by silicon sublimation, but not for the c(2 x 2) surface produced by C2H4 exposure. It was postulated that hydrogen, released by the thermal decomposition of C2H4, saturated silicon dangling bonds in the second atomic layer, thus suppressing dimer formation.

Structural Analysis of the β-SiC(100)-c(2 x 2) Surface Reconstruction by Automated Tensor Low-Energy Electron Diffraction. J.M.Powers, A.Wander, P.J.Rous, M.A.Van Hove, G.A.Somorjai: Physical Review B, 1991, 44, 11159-66