Imaging Stacking Order in Few-Layer Graphene

TL;DR

This paper presents a Raman imaging technique to accurately identify and visualize stacking sequences in few-layer graphene, revealing stable rhombohedral domains in exfoliated samples.

Contribution

The authors develop a novel Raman-based method for spatially resolving stacking order in FLG, enabling direct visualization of stacking domains.

Findings

15% of tri- and tetra-layer graphene has rhombohedral stacking domains

Rhombohedral domains are micron-sized and stable at high temperatures

The method allows direct visualization of stacking sequences in FLG

Abstract

Few-layer graphene (FLG) has been predicted to exist in various crystallographic stacking sequences, which can strongly influence the electronic properties of FLG. We demonstrate an accurate and efficient method to characterize stacking order in FLG using the distinctive features of the Raman 2D-mode. Raman imaging allows us to visualize directly the spatial distribution of Bernal (ABA) and rhombohedral (ABC) stacking in tri- and tetra-layer graphene. We find that 15% of exfoliated graphene tri- and tetra-layers is comprised of micron-sized domains of rhombohedral stacking, rather than of usual Bernal stacking. These domains are stable and remain unchanged for temperatures exceeding $800^{\circ}$C.