Tunneling Recombination in Optically Pumped Graphene with Electron-Hole Puddles

We evaluate recombination of electrons and holes in optically pumped graphene associated with the interband tunneling between electron-hole puddles and calculate the recombination rate and time. It is demonstrated that this mechanism can be dominant in a wide range of pumping intensities. We show that the tunneling recombination rate and time are nonmonotonic functions of the quasi-Fermi energies of electrons and holes and optical pumping intensity. This can result in hysteresis phenomena.