Transmission Kikuchi diffraction: The impact of the signal-to-noise ratio

Tomasz Tokarski; Gert Nolze; Aimo Winkelmann; Łukasz Rychłowski; Piotr Bała; Grzegorz Cios

doi:10.1016/j.ultramic.2021.113372

Transmission Kikuchi diffraction: The impact of the signal-to-noise ratio

Ultramicroscopy. 2021 Nov:230:113372. doi: 10.1016/j.ultramic.2021.113372. Epub 2021 Aug 14.

Authors

Tomasz Tokarski¹, Gert Nolze², Aimo Winkelmann³, Łukasz Rychłowski⁴, Piotr Bała⁵, Grzegorz Cios⁶

Affiliations

¹ Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland. Electronic address: tokarski@agh.edu.pl.
² Federal Institute for Materials, Research and Testing (BAM), Unter den Eichen 87, 12205 Berlin, Germany. Electronic address: gert.nolze@bam.de.
³ Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland. Electronic address: winkelmann@agh.edu.pl.
⁴ Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland. Electronic address: rychlowski@agh.edu.pl.
⁵ Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland; Faculty of Metals and Industrial Computer Science, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland. Electronic address: pbala@agh.edu.pl.
⁶ Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland. Electronic address: ciosu@agh.edu.pl.

PMID: 34479040
DOI: 10.1016/j.ultramic.2021.113372

Abstract

Signal optimization for transmission Kikuchi diffraction (TKD) measurements in the scanning electron microscope is investigated by a comparison of different sample holder designs. An optimized design is presented, which uses a metal shield to efficiently trap the electron beam after transmission through the sample. For comparison, a second holder configuration allows a significant number of the transmitted electrons to scatter back from the surface of the sample holder onto the diffraction camera screen. It is shown that the secondary interaction with the sample holder leads to a significant increase in the background level, as well as to additional noise in the final Kikuchi diffraction signal. The clean TKD signal of the optimized holder design with reduced background scattering makes it possible to use small signal changes in the range of 2% of the camera full dynamic range. As is shown by an analysis of the power spectrum, the signal-to-noise ratio in the processed Kikuchi diffraction patterns is improved by an order of magnitude. As a result, the optimized design allows an increase in pattern signal to noise ratio which may lead to increase in measurement speed and indexing reliability.

Keywords: EBSD; SEM; Sample holder; Transmission Kikuchi diffraction.