Graphene nanoribbon tunneling field effect transistors

The electron-hole symmetry characteristic of graphene nanoribbons (GNRs) gives rise to the electron (hole) tunneling through valence (conduction) band states. By employing this property we have numerically investigated GNR field effect transistors with p+-type source and drain in the presence of a gate voltage-induced n-type channel using the non-equilibrium Greenʹs function formalism. For long channels, the traditional FET-like I-V behavior is achieved, but at short channels, the sub threshold current opens up an oscillatory dependence on the gate voltage with a considerable amount of current of over 10−6 A. This is the characteristic current behavior of resonant tunneling transistors that exhibit regions of negative differential resistance. The calculated discrete density of states in the channel attributes this behavior to the constructed n-type channel island between p-type source and drain with thin barriers formed by the energy gap.