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arXiv · 2002.01595

Suppressing dynamical diffraction artefacts in differential phase contrast scanning transmission electron microscopy of long-range electromagnetic fields via precession

T. Mawson·A. Nakamura·T. C. Petersen·N. Shibata·H. Sasaki·D. M. Paganin·M. J. Morgan·S. D. Findlay
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Abstract

In differential phase contrast scanning transmission electron microscopy (DPC-STEM), variability in dynamical diffraction resulting from changes in sample thickness and local crystal orientation (due to sample bending) can produce contrast comparable to that arising from the long-range electromagnetic fields probed by this technique. Through simulation we explore the scale of these dynamical diffraction artefacts and introduce a metric for the magnitude of their confounding contribution to the contrast. We show that precession over an angular range of a few milliradian can suppress this confounding contrast by one-to-two orders of magnitude. Our exploration centres around a case study of GaAs near the [011] zone-axis orientation using a probe-forming aperture semiangle on the order of 0.1 mrad at 300 keV, but the trends found and methodology used are expected to apply more generally.

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T. Mawson, A. Nakamura, T. C. Petersen, N. Shibata, H. Sasaki, D. M. Paganin, M. J. Morgan, S. D. Findlay. 2020-02-05. Suppressing dynamical diffraction artefacts in differential phase contrast scanning transmission electron microscopy of long-range electromagnetic fields via precession. https://arxiv.org/abs/2002.01595

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