Full-Quantum Calculations of Low-Field Channel Mobility in Graphene Nanoribbon FETs Including Acoustic Phonon Scattering and Edge Roughness Effects

The low-field channel mobility of graphene nanoribbon (GNR) FETs is investigated through an atomistic full-quantum numerical model including elastic acoustic phonon (AP) scattering and edge roughness (ER), the latter being treated via a direct statistical approach. We find that, for narrow GNRs (W = 1 ÷ 2 nm), quantum localization effects due to ER become important, so that it is not possible to define an ER limited mobility. In this regime, the inclusion of AP scattering results in a current increase rather than decrease, due to phase breaking, which partially recovers the ohmic regime. The resulting total mobility extracted from a long channel GNR-FET biased in the ON-state is not far from the measured mobility of a GNR of comparable dimensions.