▎ 摘　　要

The authors have proposed a comprehensive analytical model for evaluating the impact ionization rate of electrons in monolayer graphene nanoribbons (GNRs). The impact ionization phenomena have been viewed as a multistage scattering process. All possible combinations of optical phonon scattering and electron-electron collision events prior to the impact ionization have been taken into account in the model. The impact ionization rate of electrons in monolayer GNR has been calculated and results are compared with the numerical data obtained from an analytical model proposed earlier. The effects of temperature and sheet electron concentration on the ionization rate have also been studied.