Journal article
Direct observation of depth-dependent atomic displacements associated with dislocations in gallium nitride
JG Lozano, H Yang, MP Guerrero-Lebrero, AJ D'Alfonso, A Yasuhara, E Okunishi, S Zhang, CJ Humphreys, LJ Allen, PL Galindo, PB Hirsch, PD Nellist
Physical Review Letters | Published : 2014
Abstract
We demonstrate that the aberration-corrected scanning transmission electron microscope has a sufficiently small depth of field to observe depth-dependent atomic displacements in a crystal. The depth-dependent displacements associated with the Eshelby twist of dislocations in GaN normal to the foil with a screw component of the Burgers vector are directly imaged. We show that these displacements are observed as a rotation of the lattice between images taken in a focal series. From the sense of the rotation, the sign of the screw component can be determined.
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Grants
Awarded by Engineering and Physical Sciences Research Council
Funding Acknowledgements
We gratefully acknowledge financial support from the EPSRC (P. D. N. and J. G. L., Grants No. EP/F048009/1 and No. EP/K032518/1; C. J. H., Grant No. EP/I012591/1), and the European Union Seventh Framework Programme under Grant No. 312483-ESTEEM2 (Integrated Infrastructure Initiative-I3). M. P. G. L. and P. L. G. acknowledge financial support from the Spanish MINECO (Projects No. TEC2011-29120-C05-03, No. MAT2010-15206 and CONSOLIDER No. CSD2009-00013), and the Junta de Andalucia (PAI research group TIC-145 and excellence Project No. P12-TEP-3055). This research was also supported under the Australian Research Council's Discovery Projects funding scheme (Project No. DP110102228) and its DECRA funding scheme (Project No. DE130100739).