Theoretical limits of electron and hole doping in single layer graphene from DFT calculations

Density functional theory calculations suggest a pronounced hole electron doping asymmetry in a single layer graphene. It turns out that a single graphene sheet can sustain doping levels up to 0.1 holes or up to a remarkably large 1.9 electrons per atom while maintaining dynamical [phonon] stability. Estimates of the superconducting critical temperature in the electron doped regime based on McMillans formula reveal two local maxima in the function of doping level which correlate with the local maxima of the electron phonon coupling constant.