Kikuchi pattern simulations of backscattered and transmitted electrons

Aimo Winkelmann, Gert Nolze, Grzegorz Cios, Tomasz Tokarski, Piotr Bała, Ben Hourahine, Carol Trager‐Cowan

Research output: Contribution to journalArticlepeer-review

Abstract

We discuss a refined simulation approach which treats Kikuchi diffraction patterns in electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). The model considers the result of two combined mechanisms: (a) the dynamical diffraction of electrons emitted coherently from point sources in a crystal and (b) diffraction effects on incoherent diffuse intensity distributions. Using suitable parameter settings, the refined simulation model allows to reproduce various thickness- and energy-dependent features which are observed in experimental Kikuchi diffraction patterns. Excess-deficiency features are treated by the effect of gradients in the incoherent background intensity. Based on the analytical two-beam approximation to dynamical electron diffraction, a phenomenological model of excess-deficiency features is derived, which can be used for pattern matching applications. The model allows to approximate the effect of the incident beam geometry as a correction signal for template patterns which can be reprojected from pre-calculated reference data. As an application, we find that the accuracy of fitted projection centre coordinates in EBSD and TKD can be affected by changes in the order of 10-3-10-2 if excess-deficiency features are not considered in the theoretical model underlying a best-fit pattern matching approach. Correspondingly, the absolute accuracy of simulation-based EBSD strain determination can suffer from biases of a similar order of magnitude if excess-deficiency effects are neglected in the simulation model.
Original languageEnglish
Pages (from-to)157-184
Number of pages28
JournalJournal of Microscopy
Volume284
Issue number2
Early online date18 Jul 2021
DOIs
Publication statusPublished - 30 Nov 2021

Keywords

  • electron diffraction
  • EBSD
  • Kikuchi diffraction
  • pattern matching

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