| Summary: | We investigate the dynamics of photoexcited carriers and non-equilibrium phonons in graphene under the linear energy dispersion approximation by solving the microscopic kinetic Bloch equations. The pump and drift effects from the laser field as well as the relevant scatterings (including Coulomb scattering with dynamic screening) are explicitly included. When the pump-photon energy is high enough (with the oscillation period much smaller than the pulse width and the scattering time), the influence of the drift term is shown to be negligible and the isotropic hot-electron Fermi distribution with separate conduction- and valence-band chemical potentials is established under scattering during the linearly polarized laser pulse investigated here. However, in the case with low pump-photon energy (with the oscillation period larger than the pulse width), the drift term is important and leads to a net momentum transfer from the electric field to the electrons. Owing to this net momentum and the dominant Coulomb scattering, a drifted Fermi distribution different from the one established under static electric field is found to be established in several hundred femtoseconds. We also show that the Auger process investigated in the literature involving only the diagonal terms of density matrices is forbidden by the dynamic screening. However, we propose an Auger process involving interband coherence and show that it contributes to the dynamics of carriers when the pump-photon energy is low (comparable with the variation speed of the distribution). In addition, the anisotropically momentum-resolved hot-phonon temperatures due to the linearly polarized light are also investigated, with the underlying physics revealed.
|
|---|