Partial dislocation core distribution in GaN using high resolution transmission electron microscopy

Joseph Kioseoglou ,  George P. Dimitrakopulos ,  Philomela Komninou ,  Thomas Kehagias ,  Theodoros Karakostas 

Dept. of Physics, Aristotle University of Thessaloniki, 54 124 Thessaloniki, Greece, Thessaloniki 54 124, Greece

Abstract

High resolution transmission electron microscopy (HRTEM) observations of 1/6 <20-23> edge partial dislocations delineating the I1 basal stacking fault in wurtzite GaN are evaluated by the use of geometric phase analysis and image simulations. The I1 stacking fault is introduced by a shear following a vacancy or interstitial disc precipitation and it may be bounded by an edge or mixed type partial dislocation. The geometric phase analysis of the HRTEM images is used in order to extract the strain field of the partial dislocations. Atomic models of these partials have been obtained previously from anistotropic elasticity and molecular dynamics calculations using a modified Stillinger-Weber type empirical interatomic potential. The core radius is determined on the experimental micrographs using the dislocation distribution tensor, which presents non-zero values only at the dislocation core, and it is found in agreement with the empirical potential calculations. Image simulations of the relaxed atomic models are employed for identification of the core structures. Strain and dislocation distribution components measured on the simulated images are compared with the relative components of the experimental micrographs.

 

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Presentation: oral at E-MRS Fall Meeting 2005, Symposium F, by Joseph Kioseoglou
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-24 14:07
Revised:   2009-06-07 00:44