Convergent-beam electron diffraction characterization of dislocations in GaS single crystals

Abstract

The effects of dislocations in GaS single crystals both on the high symmetry zone-axis convergent-beam electron diffraction patterns and on the Tanaka patterns have been studied. The dislocations induce splitting in some reflections of the low camera length diffraction patterns. The modifications have been analyzed according to the kinematical theory, so the splitting and the unsplitting of the reflections correspond to the visibility and invisibility of the defect. The Burgers vectors of the dislocations have been determined by the analysis of a single zone-axis diffraction pattern. In addition, the deformations induced by isolated dislocations in Tanaka patterns have been analyzed and the distortions have been seen to depend on the character of the observed dislocation. A quick discrimination among edge, screw and mixed dislocations has been performed by the analysis of the Tanaka pattern distortion.