The key role of nanoscale surface facets on the mechanical strength and failure of wurtzite and periodically twinned zinc-blende nanowires

Using molecular dynamics, we study the role of the surface facets of III-V nanowires on their failure during tensile deformation. We find that wurtzite (WZ) nanowires can withstand higher levels of stress and strain at failure compared to zinc-blende (ZB) nanowires. We observe that it is easier to nucleate a crack on a ZB nanowire due to the stress singularities that occur at the intersection of two opposing {111} facets. In WZ nanowires, we observe that cracks always nucleate at the intersection between two adjacent {11 (2) over bar} surface facets. We explain these phenomena using fracture mechanics techniques based on energetics of crack formation.