Excitons in Graphene and the Influence of the Dielectric Environment
arXiv:1107.5653
Abstract
The exciton Wannier equation for graphene is solved for different background dielectric constants. It is shown that freestanding graphene features strong Coulomb effects with a very large exciton binding energy exceeding eV. A second-order transition to a weak Coulomb regime is found if the effective background dielectric constant exceeds a critical value. All bound-state solutions vanish for epitaxial graphene on a substrate with large background permittivity, such as SiC.
4 pages, 2 figures