Gate-controllable negative differential conductance in graphene tunneling transistors

The transport characteristics and the possibility of controlling the negative differential conductance (NDC) in graphene tunnel field-effect transistors are investigated by means of numerical simulation. We find that an NDC effect can be achieved while the peak current and the peak-to-valley ratio (PVR) are controllable by tuning the gate voltage. Moreover, compared to the case of P-N junctions (Esaki diodes), the controllability of the potential profile in the gated region is shown to make the peak current higher and the PVR much less sensitive to the transition length between the two highly doped zones of the source and drain contacts. This work can stimulate further applications of this device in the field of high-frequency circuits, besides its potential for low-power digital operation.