Raman scattering and tunable electron–phonon coupling in single layer graphene

Graphene, the two-dimensional hexagonal lattice of carbon atoms, is promising for future electronic devices and for studies of fundamental interactions. New behaviors are linked to the extreme reduction in dimensionality to the atomic level and to the presence of Dirac fermion charge carriers. Here we review our recent work on Raman scattering studies in single layer graphene in which carrier densities are gate-modulated by the electric-field-effect (EFE). The couplings of long wavelength optical phonons (the G -band) with Dirac fermions display remarkable changes in energy and line-width that are tunable by the EFE. In these studies Raman methods emerge as tools for studies of unique properties of charge carriers in graphene such as particle–hole symmetry of Dirac fermions and the impact of disorder.