Raman spectra of bilayer graphene to probe the electrostatic environment

TL;DR

This paper demonstrates that Raman spectroscopy can quantitatively analyze the electrostatic environment of bilayer graphene by examining shifts and broadening in its Raman spectra influenced by electron concentration and external electric fields.

Contribution

It introduces a method to interpret Raman spectra of bilayer graphene for determining charge sources and electrostatic conditions, considering dynamic phonon effects and band gap modifications.

Findings

Raman spectra vary with electron concentration and electric field.

Analysis allows quantification of atmospheric and substrate charges.

Raman spectroscopy can characterize electrostatic environments in graphene.

Abstract

The Raman shift, broadening, and relative Raman intensities of bilayer graphene are computed as functions of the electron concentration. We include dynamic effects for the phonon frequencies and we consider the gap induced in the band structure of bilayer graphene by an external electric field. We show that from the analysis of the Raman spectra of gated bilayer graphene it is possible to quantitatively identify the amount of charges coming from the atmosphere and from the substrate. These findings suggest that Raman spectroscopy of bilayer graphene can be used to characterize the electrostatic environment of few-layers graphene.