Resolving the Burgers vector for individual GaN dislocations by electron channeling contrast imaging

We report evidence for non-destructive determination of dislocation type and Burgers vector direction in GaN using electron channeling contrast imaging (ECCI) inside a scanning electron microscope. Forescattered electron intensity fluctuations generated by threading dislocations exhibit characteristic spatial profiles indicative of dislocation type (screw, edge) and Burgers vector direction. Simulated channeling contrast features by two-beam dynamical diffraction calculations show qualitative agreement with recorded images. Forescatter ECCI sensitivity to atomic steps and low-angle grain boundaries in GaN allow for additional confirmation. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.