Analysis of structural distortion in Eshelby twisted InP nanowires by scanning precession electron diffraction
Transmission electron microscopes (TEM) are widely used in nanotechnology research. However, it is still challenging to characterize nanoscale objects; their small size coupled with dynamical diffraction makes interpreting real- or reciprocal-space data difficult. Scanning precession electron diffraction ((S)PED) represents an invaluable contribution, reducing the dynamical contributions to the diffraction pattern at high spatial resolution. Here a detailed analysis of wurtzite InP nanowires (30–40 nm in diameter) containing a screw dislocation and an associated wire lattice torsion is presented. It has been possible to characterize the dislocation with great detail (Burgers and line vector, handedness). Through careful measurement of the strain field and comparison with dynamical electron diffraction simulations, this was found to be compatible with a Burgers vector modulus equal to one hexagonal lattice cell parameter despite the observed crystal rotation rate being larger (ca. 20%) than that predicted by classical elastic theory for the nominal wire diameter. These findings corroborate the importance of the (S)PED technique for characterizing nanoscale materials.
Keywordselectron microscopy scanning precession electron diffraction Eshelby twist screw dislocation nanowire indium phosphide
We thank Dr Z. Saghi for taking the ADF-STEM images of the twisted wires. D. U. acknowledges financial support from the Brazilian Agencies FAPESP (No. 2014/01045-0) and CNPq (No. 302767/2012-6). A. E. acknowledges funding from the Royal Society. P. A. M. acknowledges financial support from European Research Council through grant 291522-3DIMAGE and the EPSRC grant number EP/R025517/1. M. A. C. acknowledges financial support from FAPESP (Nos. 2013/02300-1 and 2013/10957-0) and CNPq (No. 479486/ 2012-3). L. H. G. T. and P. A. M. acknowledge funding from the European Union Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 312483 (ESTEEM2).
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