Revealing the 3D Structure of Graphene Defects

TL;DR

This paper introduces a novel method using transmission electron microscopy images at different angles to determine the 3D structure of graphene defects, revealing correlations with misorientation angles and comparing results with theoretical predictions.

Contribution

The paper presents a new approach for reconstructing 3D defect structures in graphene from TEM images, enabling direct comparison with theoretical models.

Findings

Lower misorientation angles lead to stronger corrugation.

Measured kink angles are smaller than the largest predicted values.

The method successfully reconstructs 3D structures of grain boundaries.

Abstract

We demonstrate insights into the three-dimensional structure of defects in graphene, in particular grain boundaries, obtained via a new approach from two transmission electron microscopy images recorded at different angles. The structure is obtained through an optimization process where both the atomic positions as well as the simulated imaging parameters are iteratively changed until the best possible match to the experimental images is found. We first demonstrate that this method works using an embedded defect in graphene that allows direct comparison to the computationally predicted three-dimensional shape. We then applied the method to a set of grain boundary structures with misorientation angles nearly spanning the whole available range (2.6-29.8{\deg}). The measured height variations at the boundaries reveal a strong correlation with the misorientation angle with lower angles resulting in stronger corrugation and larger kink angles. Our results allow for the first time a direct comparison with theoretical predictions for the corrugation at grain boundaries and we show that the measured kink angles are significantly smaller than the largest predicted ones.