Complementary ADF-STEM: a Flexible Approach to Quantitative 4D-STEM

TL;DR

This paper introduces a flexible method for analyzing 4D-STEM data that leverages the full electron flux, enhancing resolution and contrast in imaging while optimizing detector use and electron dose.

Contribution

It presents a new approach to quantify 4D-STEM data by utilizing electrons beyond detector limits, improving imaging flexibility and contrast.

Findings

Enables synthesis of high-contrast complementary ADF images from low-angle diffraction.

Allows optimization of electron dose and detector dynamic range.

Increases experimental flexibility in 4D-STEM analysis.

Abstract

Scanning transmission electron microscopy (STEM) has a broad range of applications in materials characterization, including real-space imaging, spectroscopy, and diffraction, at length scales from the micron to sub-{\AA}ngstr\"om. The recent development and adoption of high-speed, direct electron STEM detectors has enabled diffraction patterns to be collected at each probe position, generating four-dimensional STEM (4D-STEM) datasets and opening new imaging modalities. However, the limited pixel numbers in these detectors enforce a tradeoff between angular resolution and maximum collection angle. In this paper, we describe a straightforward method for quantifying 4D-STEM data by utilizing the full flux of the electron beam, including electrons scattered beyond the limits of the detector. This enables significantly increased experimental flexibility, including the synthesis of quantitative, high-contrast complementary annular dark field (cADF) STEM images from low-angle diffraction patterns whilst maintaining high angular resolution; as well as the optimization of electron dose and the more effective use of low dynamic range detectors.