Inelastic carrier lifetime in a coupled graphene/electron-phonon system: Role of plasmon-phonon coupling

We calculate the inelastic scattering rates and the hot-electron inelastic mean free paths for both monolayer and bilayer graphene on a polar substrate. We study the quasiparticle self-energy by taking into account both electron-electron and electron-surface-optical-phonon interactions. In this calculation the leading-order dynamic screening approximation (G(0)W approximation) is used to obtain the quasiparticle self-energy by treating electrons and phonons on an equal footing. We find that the strong coupling between the surface-optical phonon and the plasmon leads to an additional decay channel for the quasiparticle through the emission of the coupled mode, and gives rise to an abrupt increase in the scattering rate, which is absent in the uncoupled system. In monolayer graphene a single jump in the scattering rate occurs, arising from the emission of the low-energy branch of the coupled plasmon-phonon modes. In bilayer graphene the emission of both low-and high-energy branches of the coupled modes contributes to the scattering rate and gives rise to two abrupt changes in the scattering rate. The jumps in the scattering rate can potentially be used in hot-electron devices such as switching devices and oscillators.