Fermi Velocity Modulation Induced Low‐Bias Negative Differential Resistance in Graphene Double Barrier Resonant Tunneling diode

Negative differential resistance (NDR) devices are adequate candidates for the functional devices applicable to the next‐generation integrated circuit technology so‐called “Beyond CMOS.” Here, a graphene velocity‐modulation‐barrier resonant‐tunneling diode operating at room temperature is proposed. The current–voltage characteristics of the device are analyzed using the non‐equilibrium Green's function technique. It is found that the Fermi velocity barrier in the well/barrier region manipulates the tunneling transmission probability by suppressing the Klein region and improving the resonant tunneling leading to NDR. For special values of velocity barriers, resonant states have maximum alignment with each other which increases peak current with a high peak to valley ratio (PVR). The width and the position of the NDR window are controlled and engineered by the device dimensions and the height of potential barriers. The smaller the device showed the better the NDR properties such as larger current density and maximum PVR. Taken together, the results reveal that adequate magnitude of the Fermi velocity in graphene barrier can be an impressive concept for the fabrication of emerging tunneling devices. By using different substrates and metal gates, Fermi velocity is modulated in graphene well/barrier structure. In the case without Fermi velocity modulation (top), resonant tunneling accompanied with Klein tunneling while introduction of the two various Fermi velocity of υF1 and υF2 with proper ratio Fermi velocity barrier between well and barrier improves negative differential resistance performance of device via suppressing Klein tunneling (bottom).