High Precision Orientation Mapping from 4D-STEM Precession Electron Diffraction data through Quantitative Analysis of Diffracted Intensities

TL;DR

This paper introduces a quantitative method for high-precision orientation mapping in nanomaterials using 4D-STEM precession electron diffraction, achieving significantly improved angular resolution over traditional techniques.

Contribution

It presents a novel quantitative analysis approach for orientation mapping in 4D-STEM data, utilizing dynamical diffraction simulations for enhanced accuracy.

Findings

Achieved ~0.03° angular precision in orientation mapping.

Demonstrated the method on InP nanowires with high accuracy.

Showed potential for detailed deformation field analysis.

Abstract

The association of scanning transmission electron microscopy (STEM) and the detection of a diffraction pattern at each probe position (so-called 4D-STEM) represents one of the most promising approaches to analyze structural properties of materials with nanometric resolution and low irradiation levels. This is widely used for texture analysis of material using automated crystal orientation mapping (ACOM). Herein, we perform orientation mapping in InP nanowires exploiting precession electron diffraction (PED) patterns acquired by an axial CMOS camera. Crystal orientation is determined at each probe position by the quantitative analysis of diffracted intensities minimizing a residue comparing experiments and simulations in analogy to structural refinement. Our simulations are based on the two-beam dynamical diffraction approximation and yield a high angular precision (~0.03 degrees), much lower than the traditional ACOM based on pattern matching algorithms (~1 degrees). We anticipate that simultaneous exploration of both spot positions and high precision crystal misorientation will allow the exploration of the whole potentiality provided by PED-based 4D-STEM for the characterization of deformation fields in nanomaterials.