Nanomechanical behavior of single taper-free GaAs nanowires unravelled by in-situ TEM mechanical testing and molecular dynamics simulation

Nanowire-based devices have been widely applied in optoelectronics, sensors, generators and spectroscopy. These nanowires are typically subjected to mechanical conditions during manufacture or operation. Thus, a compressive understanding of nanowire mechanical properties is increasingly required. However, only limited results have been reported owing to the challenges inherent in nanomechanical testing, particularly for quantitative tensile deformation. Herein, taper-free zinc blende GaAs nanowires with a 120 nm diameter are grown along the [111]B direction using metalorganic vapor phase epitaxy. The mechanical properties and fracture mechanisms of these single-phase GaAs nanowires are explored by in-situ uniaxial tensile deformation inside a transmission electron microscope, followed by molecular dynamics simulations. Under tensile stress, GaAs nanowires deform overally elastically until sudden brittle fracture at 3.79% strain. The fracture strength and elastic modulus are experimentally determined as 4.0 and 109.5 GPa, respectively, which are much smaller than other reported results based on compression. The tensile deformation and fracture mechanisms are further explored using molecular dynamics simulations, and the effects of different crystal structures on the GaAs nanowire mechanical behavior are discussed. These results assess the mechanical behavior of single GaAs nanowires and present critical insights into the reliable design of engineering nanodevices.