Domain (Grain) Boundaries and Evidence of Twin Like Structures in CVD Grown Graphene

TL;DR

This study uses advanced TEM techniques to analyze domain boundaries in CVD-grown graphene, revealing boundary orientations, defects, adsorbates, and evidence of twin-like structures, which are crucial for understanding and engineering graphene properties.

Contribution

It provides the first detailed TEM-based characterization of boundary orientations, defects, and twin-like structures in CVD graphene, advancing fundamental understanding.

Findings

Boundary misorientation angles mostly between 11-30 degrees

Presence of adsorbates and dangling bonds at boundaries

Evidence of twin-like boundary structures

Abstract

Understanding and engineering the domain boundaries in chemically vapor deposited (CVD) monolayer graphene will be critical for improving its properties. In this study, a combination of transmission electron microscopy (TEM) techniques including selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM), and dark field (DF) TEM was used to study the boundary orientation angle distribution and the nature of the carbon bonds at the domain boundaries. This report provides an important first step towards a fundamental understanding of these domain boundaries. The results show that, for the graphene grown in this study, the 46 measured misorientation angles are all between 11-30 degrees (with the exception of one at 7 degrees). HRTEM images show the presence of adsorbates in almost all of the boundary areas. When a boundary was imaged, defects were seen (dangling bonds) at the boundaries that likely contribute to adsorbates binding at these boundaries. DFTEM images also showed the presence of a 'twin like' boundary.