Energy of Si(111) dimer-stacking-fault structures

In this work we show that the relative formation energies of stacking faults, dimer rows, and rebonded corner holes can be determined by analyzing the size distribution of dimer-stacking-fault (DS) structures that are found along extended 〈112¯〉 step lengths of the Br-passivated Si(111)-$1\times 1$ surface. Using this method we report an energy of 1.75 eV for the rebonded corner holes associated with these DS structures. These energies are in turn used to predict the partitioning of DS structures along short 〈112¯〉 step lengths, yielding results that are in good agreement with experiment. We also introduce a model that describes DS structures as an ordered collection of vacancies subject to the topological bonding constraints of the Si diamond lattice. In this manner, we establish that there is a thermodynamic driving force for the coalescence and formation of large isolated DS structures on adsorbate-stabilized Si(111)-$1\times 1$ terraces. This result has important implications for the feasibility of forming defect-free bulk-terminated Si(111) surfaces by exposure of the Si(111)-$7\times 7$ surface to hydrogen or halogens.