Negative Differential Resistance and Steep Switching in Chevron Graphene Nanoribbon Field-Effect Transistors

We show that recently fabricated Chevron type graphene nanoribbons act as a monolithic superlattice structure. This is enabled by the large periodic unit cells with regions of different effective bandgaps in these nanoribbons, resulting in minibands and gaps in the density of states above the conduction band edge. Quantum transport calculations based on non-equilibrium Green's function formalism reveal that a negative differential resistance (NDR) is expected to manifest in these nanoribbons. Due to the relatively low density of states, such NDR behavior can also be modulated with a gate electric field. We show that a sub-thermal subthreshold swing (<;kT/q) can potentially be obtained in a three-terminal configuration, even in the presence of optical phonon scattering.