Evolution of the Raman 2D’ mode in monolayer graphene during electrochemical doping

Abstract

Effective charge doping and control of the Fermi level shift is a crucial aspect in graphene device fabrication. Raman spectroscopy is extensively used for primary characterization of such samples, however, quantification of carrier concentration using the known G-2D vector analysis can pose problems when more sources of phonon renormalization are present, for example lattice deformation or disorder. In such cases, analysis of another Raman mode can provide the needed missing information. In this study, chemical vapor-deposition-grown single-layer graphene was monitored by in-situ Raman spectroelectrochemistry with the focus on the behavior of the 2D’ mode upon the application of electrochemical potential. We analyzed the changes of the Raman peak intensity, frequency and linewidth of the 2D’ mode as a function of electrode potential in detail and compared the obtained results with well-known behavior of the G and 2D modes during electrochemical doping.