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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 revealed 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 multislice simulations using Grillo s strain channelling equation, is proposed to elucidate the physical origin of such complex contrast phenomena.
Nanotechnology research requires the routine use of characterization methods with high spatial resolution. These experiments are rather costly, not only from the point of view of the expensive microscopes, but also considering the need of a rather sp
The arrival of direct electron detectors (DED) with high frame-rates in the field of scanning transmission electron microscopy has enabled many experimental techniques that require collection of a full diffraction pattern at each scan position, a fie
The use of coherent x-ray beams has been greatly developing for the past decades. They are now used by a wide scientific community to study biological materials, phase transitions in crystalline materials, soft matter, magnetism, strained structures,
We present an aberration corrected scanning transmission electron microscopy (ac-STEM) analysis of the perovskite (LaFeO3) and pyrochlore (Yb2Ti2O7 and Pr2Zr2O7) oxides and demonstrate that both the shape and contrast of visible atomic columns in ann
Considering the recent breakthroughs in the synthesis of novel two-dimensional (2D) materials from layered bulk structures, ternary layered transition metal borides, known as MAB phases, have come under scrutiny as a means of obtaining novel 2D trans