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

Abstract

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 ${\mathrm{C}}_2$ ${\mathrm{H}}_4$. Our results showed that both methods produced a surface terminated with ${\mathrm{C}}_2$ 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 ${\mathrm{C}}_2$ ${\mathrm{H}}_4$ exposure. We postulate that hydrogen, released by the thermal decomposition of ${\mathrm{C}}_2$ ${\mathrm{H}}_4$, saturated silicon dangling bonds in the second atomic layer, suppressing dimer formation.