  Taper-free InP twinning superlattice (TSL) nanowires with an average twin
spacing of ~ 13 nm were grown along the zinc-blende close-packed [111]
direction using metalorganic vapor phase epitaxy. The mechanical properties and
fracture mechanisms of individual InP TSL nanowires in tension were ascertained
by means of in situ uniaxial tensile tests in a transmission electron
microscope. The elastic modulus, failure strain and tensile strength along the
[111] direction were determined. No evidence of inelastic deformation
mechanisms was found before fracture, which took place in a brittle manner
along the twin boundary. The experimental results were supported by molecular
dynamics simulations of the tensile deformation of the nanowires that also
showed that the fracture of twinned nanowires occurred in the absence of
inelastic deformation mechanisms by the propagation of a crack from the
nanowire surface along the twin boundary.
