Structural analysis of the β-SiC(100)-c(2×2) surface reconstruction by automated tensor low-energy electron diffraction

The atomic structure of the {β}-SiC(100)-c(2×{}2) surface was analyzed using dynamical calculations of low-energy electron-diffraction intensities. The c(2×{}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×{}1) surface at 1125 K to C₂{H}₄$. Our results showed that both methods produced a surface terminated with ${C}₂$ groups in staggered silicon bridge sites. Weak silicon dimer bonds were found in the second atomic layer of the c(2×{}2) surface produced by silicon sublimation, but not for the c(2×{}2) surface produced by C₂{H}₄$ exposure. We postulate that hydrogen, released by the thermal decomposition of ${C}₂H₄, saturated silicon dangling bonds in the second atomic layer, suppressing dimer formation.