Multibeam Electron Diffraction

TL;DR

Multibeam Electron Diffraction (MBED) uses multiple probes in TEM to improve crystal orientation mapping and enable 3D tomographic reconstruction without sample tilting, enhancing analysis of polycrystalline samples.

Contribution

This paper introduces the MBED technique, utilizing multiple probes simultaneously in TEM, and demonstrates its effectiveness for orientation mapping and 3D reconstruction.

Findings

MBED accurately maps crystalline orientations.

MBED enables 3D tomography without sample tilting.

FIB can produce MBED apertures effectively.

Abstract

One of the primary uses for transmission electron microscopy (TEM) is to measure diffraction pattern images in order to determine a crystal structure and orientation. In nanobeam electron diffraction (NBED) we scan a moderately converged electron probe over the sample to acquire thousands or even millions of sequential diffraction images, a technique that is especially appropriate for polycrystalline samples. However, due to the large Ewald sphere of TEM, excitation of Bragg peaks can be extremely sensitive to sample tilt, varying strongly for even a few degrees of sample tilt for crystalline samples. In this paper, we present multibeam electron diffraction (MBED), where multiple probe forming apertures are used to create mutiple STEM probes, all of which interact with the sample simultaneously. We detail designs for MBED experiments, and a method for using a focused ion beam (FIB) to produce MBED apertures. We show the efficacy of the MBED technique for crystalline orientation mapping using both simulations and proof-of-principle experiments. We also show how the angular information in MBED can be used to perform 3D tomographic reconstruction of samples without needing to tilt or scan the sample multiple times. Finally, we also discuss future opportunities for the MBED method.