Observation of depth-dependent atomic displacements related to dislocations in GaN by optical sectioning in the STEM

摘要

We demonstrate that it is possible to observe depth-dependent atomic displacements in a GaN crystal due to the sufficiently small depth of field achievable in the aberrationcorrected scanning transmission electron microscope. The depth-dependent displacements associated with the Eshelby twist of screw dislocations in GaN viewed end on are directly imaged, and makes possible the determination of the sign of the Burgers vector of the dislocation. The experimental results are in good agreement with theoretical images.