An empirical potential approach to wurtzite-zinc-blende polytypism in group III-V semiconductor nanowires

The relative stability between wurtzite and zinc blende structures in group Ill-V semiconductor nanowires is systematically investigated based on an empirical potential, which incorporates electrostatic energy clue to valence-bond and ionic charges. The energy differences between wurtzite and zinc blende structures of 12 compound nanowires with diameter of 1-22 nm show that the wurtzite nanowires are stabilized for small diameter. This structural trend is found to be due to the contribution of two- and three-coordinated atoms on the nanowire facets to the system energy. We also find that the critical diameters, where the nanowires turn Out be bistable forming both wurtzite and zinc blende structures, exist at the diameter of 12-32 nm depending on the ionicity of semiconductors. The bistability implies the synthesis of nanowires exhibiting polytypes, and supports the experimental results in GaP, GaAs, InP, and InAs nanowires.