First-principles calculations on the effect of doping and biaxial tensile strain on electron-phonon coupling in graphene

Graphene has exhibited a wealth of fascinating properties, but is also known not to be a superconductor. Remarkably, we show that graphene can be made a conventional Bardeen-Cooper-Schrieffer superconductor by the combined effect of charge doping and tensile strain. While the effect of doping obviously enlarges the Fermi surface, the effect of strain profoundly increases the electron-phonon coupling. At the experimental accessible doping (∼4×1014 cm^-2) and strain (∼16%) levels, the superconducting critical temperature T_c is estimated to be as high as ∼30 K, the highest for a single-element material above the liquid hydrogen temperature.