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.

Insights into image contrast from dislocations in ADF-STEM

Spadaro M;
2019-01-01

Abstract

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.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11566/308950
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