In Situ Nanomechanics of GaN Nanowires

Huang et al., Nano Lett., 2011, 11 (4), pp 1618–1622

The deformation, fracture mechanisms, and the fracture strength of
individual GaN nanowires were measured in real time using a transmission
electron microscope−scanning probe microscope (TEM-SPM) platform.
Surface mediated plasticity, such as dislocation nucleation from a free
surface and plastic deformation between the SPM probe (the punch) and
the nanowire contact surface were observed in situ. Although local
plasticity was observed frequently, global plasticity was not observed,
indicating the overall brittle nature of this material. Dislocation
nucleation and propagation is a precursor before the fracture event, but
the fracture surface shows brittle characteristic. The fracture surface
is not straight but kinked at (10-10) or (10-11) planes. Dislocations
are generated at a stress near the fracture strength of the nanowire,
which ranges from 0.21 to 1.76 GPa. The results assess the mechanical
properties of GaN nanowires and may provide important insight into the
design of GaN nanowire devices for electronic and optoelectronic
applications.