A better understanding of the low-field mobility in graphene nano-ribbons

Band structure calculations of graphene nano-ribbons in the presence of edge disorder using the tight-binding method have been used to find a simple analytical formulation for the dispersion relationship of extended electronic states. Once inserted in a Monte-Carlo simulator accounting for phonons and edge roughness scattering, the analytical model helped us understand the ribbon width dependence of the lowfield mobility: the main responsible for the low mobility values measured in narrow ribbons is not the higher defectivity of these devices, but, instead, the increased phonon scattering rate and mobility effective mass due to the strong band structure modification induced by reduced lateral dimensions with respect to a graphene sheet.