Insights into image contrast from dislocations in ADF-STEM

Competitive mechanisms contribute to image contrast from dislocations in annular dark-field scanning transmission electron microscopy (ADF-STEM). A clear theoretical understanding of the mechanisms underlying the ADF-STEM contrast is therefore essential for correct interpretation of dislocation images. This paper reports on a systematic study of the ADF-STEM contrast from dislocations in a GaN specimen, both experimentally and computationally. Systematic experimental ADF-STEM images of the edge-character dislocations reveal a number of characteristic contrast features that are shown to depend on both the angular detection range and specific position of the dislocation in the sample. A theoretical model based on electron channelling and Bloch-wave scattering theories, supported by numerical simulations based on Grillo's strain-channelling equation, is proposed to elucidate the physical origin of such complex contrast phenomena.


Published in:
Ultramicroscopy, 200, 139-148
Year:
May 01 2019
Publisher:
Amsterdam, ELSEVIER SCIENCE BV
ISSN:
0304-3991
1879-2723
Keywords:
Laboratories:




 Record created 2019-06-18, last modified 2019-07-02


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