Revising morphology of <111>-oriented silicon and germanium nanowires

Abstract

By means of ab initio calculations we show that morphology of <111>-oriented silicon and germanium nanowires is defined by {112} and {011} facets. Changes in nanowire morphology are predicted to involve a partial transformation of {011} facets in favor of {112} facets even though the latter ones act as edges between adjacent {011} facets. Our estimates of surface energies clearly indicate a (112) surface to be thermodynamically preferable with respect to a (011) surface for both silicon and germanium. These findings can explain experimental observations of {112} facets in round-like and triangle-like morphologies of <111>-oriented silicon nanowires.