Atomic structure and formation process of the Si(1 1 1)–Sb(√7 × √7) surface phase

During the study of Sb condensation on the Si(1 1 1)–In(√3×√3) surface phase we observed the formation of a new Sb-induced surface structure with (√7×√7) lattice below 450 °C. This phase may not be prepared by direct Sb deposition on the Si(1 1 1) surface. Instead, the substitution for In atoms from T4 bonding sites by incoming Sb and formation of a γ-phase strongly determine the Sb(√7×√7) formation process. When the concentration of Sb exceeds the value of 0.2 ML the irreversible γ√3→√7 phase transition occurs. Based on STM observations, the structural model for this reconstruction has been proposed.