Raman Fingerprint of Charged Impurities in Graphene

摘要: We report strong variations in the Raman spectra for different single-layer graphene samples obtained by micromechanical cleavage. This reveals presence of excess charges, even absence intentional doping. Doping concentrations up to ∼1013cm−2 are estimated from G peak shift and width variation both position relative intensity second order 2D peak. Asymmetric peaks indicate charge inhomogeneity on a scale less than 1μm.