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

Research output: Contribution to journalArticleResearchpeer-review

1 Citation (Scopus)

Abstract

It is well known that dynamical diffraction varies with changes in sample thickness and local crystal orientation (due to sample bending). In differential phase contrast scanning transmission electron microscopy (DPC-STEM), this 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 contribution to the contrast. We show that precession over an angular range of a few milliradian can suppress this contribution to the 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.

Original languageEnglish
Article number113097
Number of pages12
JournalUltramicroscopy
Volume219
DOIs
Publication statusPublished - Dec 2020

Keywords

  • Differential phase contrast
  • Dynamical diffraction
  • Precession
  • Scanning transmission electron microscopy

Cite this