Atomic Structure of Clean Si(113) Surfaces: Theory and Experiment

High-index surfaces of Si are of potential technological interest but they tend to facet into low-index planes. The only known exception is Si(113) with a surface energy about as small as Si(001); however, its atomic structure remained unresolved. On the basis of scanning tunneling microscopy measurements and ab initio theory we present a new atomic model of Si(113) employing a novel idea of a subsurface self-interstitial. The calculated surface energy of Si(113) (3 × 2) is close to the value for Si(001)-p(2×2). The new model explains experimentally observed transitions between the 3 × 1 and 3 × 2 phases.