Picometer-precision few-tilt ptychotomography of 2D materials

TL;DR

This paper introduces a highly precise 3D atomic imaging method for fragile 2D materials, combining few tilt ptychography with dose-efficient electron microscopy, enabling detection of light atoms at unprecedented resolution and lower doses.

Contribution

It presents a novel combination of few tilt tomography and ptychography, significantly improving dose efficiency and sensitivity to light elements in 2D materials analysis.

Findings

Achieved picometer-precision localization of light atoms in 2D materials.

Reduced electron dose by a factor of 30 compared to previous methods.

Successfully applied the technique to complex materials like WS₂ and CuI.

Abstract

From ripples to defects, edges and grain boundaries, the 3D atomic structure of 2D materials is critical to their properties. However the damage inflicted by conventional 3D analysis precludes its use with fragile 2D materials, particularly for the analysis of local defects. Here we dramatically increase the potential for precise local 3D atomic structure analysis of 2D materials, with both greatly improved dose efficiency and sensitivity to light elements. We demonstrate light atoms can now be located in complex 2D materials with picometer precision at doses 30 times lower than previously possible. Moreover we demonstrate this using a material, WS$_2$, in which the light S atoms are in fact practically invisible to conventional methods. The key advance is combining the concept of few tilt tomography with highly dose efficient ptychography in scanning transmission electron microscopy. We further demonstrate the method experimentally with the even more challenging and newly discovered 2D CuI, leveraging a new extremely high temporal resolution camera.