Effect of layer number and layer stacking registry on the formation and quantification of defects in graphene

TL;DR

This study investigates how layer number and stacking order affect defect formation and quantification in graphene using Raman spectroscopy, revealing significant differences and potential overestimations in defect counts.

Contribution

It provides the first experimental verification of how stacking order influences defect detection in multilayer graphene via Raman spectroscopy.

Findings

Stacking order affects defect impact in Raman spectra.

Defect quantification can be overestimated by up to a factor of two.

Differences observed between single layer, turbostratic, and Bernal-stacked bilayer graphene.

Abstract

Correct defect quantification in graphene samples is crucial both for fundamental and applied re-search. Raman spectroscopy represents the most widely used tool to identify defects in graphene. However, despite its extreme importance the relation between the Raman features and the amount of defects in multilayered graphene samples has not been experimentally verified. In this study we intentionally created defects in single layer graphene, turbostratic bilayer graphene and Bernal stacked bilayer graphene by oxygen plasma. By employing isotopic labelling, our study reveals substantial differences of the effects of plasma treatment on individual layers in bilayer graphene with different stacking orders. In addition Raman spectroscopy evidences scattering of phonons in the bottom layer by defects in the top layer for Bernal-stacked samples, which can in general lead to overestimation of the number of defects by as much as a factor of two.