Structural models for Sb on Si(113): an experimental and theoretical STM study

Abstract

We present a combined experimental (scanning tunnelling microscopy) and theoretical (ab initio calculations) study of the atomic structure of Sb Si(113) . The structural unit of the clean Si(113)3 × 2 surface contains 3 elements: a pentamer above a subsurface interstitial atom, an adatom, and a tetramer. Because the subsurface interstitials are stable only at very low Sb coverages, we attempt to describe high coverage Sb Si(113) in terms of the two remaining “conventional” elements. This leads to several possible structures with various coverages and topologies resulting from various relative positions of adatoms and tetramers as well as from occupation of atomic positions by either Si or Sb. In particular, we present arguments in favour of a specific atomic model for Sb Si(113) for a coverage of θ Sb = 0.75.