▎ 摘　　要

The relaxation process of photoexcited electrons in graphene is simulated by using a Monte Carlo method. A full-band treatment is used for the electron-phonon interaction, and an approximate treatment is used for the electron-electron interaction. The Monte Carlo simulations reveal an ultrafast relaxation of electrons with a time constant of about 20 fs, which is close to a recent experimental result. Despite the ultrafast relaxation of electrons, a population inversion for the photoexcited electron-hole system is expected. (C) 2011 The Japan Society of Applied Physics