Raman spectroscopic characterization of stacking configuration and interlayer coupling of twisted multilayer graphene grown by chemical vapor deposition

TL;DR

This study uses Raman spectroscopy to analyze the stacking and interlayer interactions in twisted multilayer graphene grown by CVD, revealing high-quality coupling and potential for controlled stacking configurations.

Contribution

It introduces a Raman-based method to identify stacking configurations and interlayer coupling in CVD-grown twisted multilayer graphene, demonstrating high-quality growth and controllable stacking.

Findings

Interlayer shear modes follow AB-stacked N-1 layers

Interlayer breathing modes follow AB-stacked N layers

High-quality interlayer coupling comparable to exfoliated samples

Abstract

Multilayer graphene (MLG) grown by chemical vapor deposition (CVD) is a promising material for electronic and optoelectronic devices. Understanding the stacking configuration and interlayer coupling of MLGs is technologically relevant and of importance for the device applications. Here, we reported a kind of twisted MLGs (tMLGs), which are formed by stacking one graphene monolayer on the top of AB-stacked MLG by rotating a certain angle between them. The twist angle of tMLGs are identified by the twist-related modes, R and R'. With increasing the total layer number of N, the observed interlayer shear modes in the tMLG flake always follow those of AB-stacked (N-1)LG, while the observed interlayer breathing modes always follow those of AB-stacked NLG, independent of its twist angle. The layer breathing coupling of the tMLGs is almost identical to that of mechanically-exfoliated tMLGs, which demonstrates the high quality of MLGs grown by CVD. This study provides an applicable approach to probe the stacking configuration and interlayer coupling of MLGs grown by CVD or related methods. This work also demonstrates the possibility to grow MLG flakes with a fixed stacking configuration, $e.g.$, t(1+$n$)LG, by the CVD method.