Role of edge facets on stability and electronic properties of III-V nanowires

Results of our ab initio calculations of 〈111〉-oriented GaP, GaAs, GaSb, InP, InAs and InSb nanowires with the zinc-blende structure indicate morphology to crucially affect their electronic properties. For these nanowires, where {011} facets characterize their hexagonal cross section, the formation of small {112} facets between the adjacent {011} ones provides a more stable structure and removes surface states from the gap region even without hydrogen passivation. Our new structural model also predicts a crossover between the indirect and direct band gap in GaP, GaAs and GaSb nanowires when increasing diameters starting from 4 nm, while InP, InAs and InSb nanowires display the direct band gap at diameters of 1.5 nm and larger. Analysis of charge distribution between atoms suggests that {011} facets are positively charged even though a (011) surface of these materials is considered to be non-polar.