title: In situ nanomechanics of GaN nanowires.
abstract: 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.
authors.affiliation: Sandia National Laboratories, Albuquerque, New Mexico 87185, United States. jhuang@sandia.gov
authors.forename: Jian Yu
authors.initials: JY
authors.lastname: Huang
authors.forename: He
authors.initials: H
authors.lastname: Zheng
authors.forename: S X
authors.initials: SX
authors.lastname: Mao
authors.forename: Qiming
authors.initials: Q
authors.lastname: Li
authors.forename: George T
authors.initials: GT
authors.lastname: Wang
mesh_terms: D055119:Elastic Modulus; D005708:Gallium / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D046911:Macromolecular Substances; C473348:gallium nitride; D005708:Gallium