3D Strain Field Reconstruction by Inversion of Dynamical Scattering

TL;DR

This paper introduces a novel 4D-STEM based method to reconstruct 3D strain fields in materials by inverting dynamical diffraction effects, enabling measurement of strain variations along the electron beam direction.

Contribution

The paper presents the first inversion-based approach for 3D strain mapping using 4D-STEM, addressing a major challenge in electron microscopy.

Findings

Successfully tested on simulated data with known ground truth.

Demonstrated application on experimental data from an AlGaN layer.

Provides accurate 3D strain reconstruction along the beam direction.

Abstract

Strain governs not only the mechanical response of materials but also their electronic, optical, and catalytic properties. For this reason, the measurement of the 3D strain field is crucial for a detailed understanding and for further developments of material properties through strain engineering. However, measuring strain variations along the electron beam direction has remained a major challenge for (scanning-) transmission electron microscopy (S/TEM). In this article, we present a method for 3D strain field determination using 4D-STEM. The method is based on the inversion of dynamical diffraction effects, which occur at strain field variations along the beam direction. We test the method against simulated data with a known ground truth and demonstrate its application to an experimental 4D-STEM dataset from an inclined pseudomorphically grown Al$_{0.47}$Ga$_{0.53}$N layer.