Charge carrier density dependent Raman spectra of graphene encapsulated in hexagonal boron nitride

The authors use low-temperature Raman spectroscopy measurements on gate-tunable graphene encapsulated in hBN to explore in detail the Raman $G$ and 2D mode frequencies and linewidths as function of the charge carrier density. This study provides a reference for Raman spectroscopy on ultraflat high-quality graphene (with a minimum 2D Raman line width of 14.5 cm${}^{\ensuremath{-}1})$ and is useful to investigate electron-phonon coupling and to benchmark graphene samples (including graphene-based heterostructures) when using Raman spectroscopy for process monitoring.