Surface influence on stability and structure of III-V nanorods: First-principles studies

We report ab initio investigations of hexagon-shaped, [111]/[0001] oriented III-V semiconductor nanowires with varying crystal structure, surface passivation, surface orientation, and diameter. Their stability is dominated by the free surface energies of the corresponding facets which differ only weakly from those of free surfaces. We observe a phase transition between local zinc-blende and wurtzite geometry versus preparation conditions of the surfaces, which is accompanied by a change in the facet orientation. The influence of the actual III-V compound remains small. The atomic relaxation of nanowires gives rise to smaller bond lengths in comparison to the bulk zinc-blende structures resulting also in somewhat reduced bilayer thicknesses parallel to the growth direction.