Accuracy and precision of position determination in ISTEM imaging of BaTiO3

Dennis Marquardt; Marco Schowalter; Florian F Krause; Tim Grieb; Christoph Mahr; Thorsten Mehrtens; Andreas Rosenauer

doi:10.1016/j.ultramic.2021.113325

Accuracy and precision of position determination in ISTEM imaging of BaTiO₃

Ultramicroscopy. 2021 Aug:227:113325. doi: 10.1016/j.ultramic.2021.113325. Epub 2021 May 23.

Authors

Dennis Marquardt¹, Marco Schowalter², Florian F Krause¹, Tim Grieb¹, Christoph Mahr¹, Thorsten Mehrtens¹, Andreas Rosenauer³

Affiliations

¹ Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany.
² Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany. Electronic address: schowalter@ifp.uni-bremen.de.
³ Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany; MAPEX Center for Materials and Processes, Universität Bremen, Bibliotheksstraße 1, 28359 Bremen, Germany.

PMID: 34045084
DOI: 10.1016/j.ultramic.2021.113325

Abstract

In this paper we study the effect of lens aberrations (spherical aberration and astigmatism), beam tilt, contamination and shot noise on the accuracy and precision of position determination in imaging scanning transmission electron microscopy (ISTEM) on the example of BaTiO₃. ISTEM images are simulated as a function of sample thickness and defocus starting from a nearly perfect microscope setting. A defocus range was identified, in which atom column positions were reliably visible and could be decently measured. By averaging over this defocus and thickness range a figure of merit was defined and used to study the influence of above mentioned disturbing effects as a function of their strength. It turned out that column positions might become inaccurate, but distances are measured accurately. These were used to obtain recommendations for the experimental setup to measure the atomic arrangement that induces ferroelectric switching of BaTiO₃.

Keywords: Atom position determination; BaTiO(3); CTEM; Imaging scanning transmission electron microscopy; STEM; TEM; Tunnel junctions.