New RTDs with enhanced operation based on black phosphorus–graphene heterostructures and a semianalytical vdW tunneling model

Abstract

Two new vertical resonant tunneling devices (RTDs) of different sizes are proposed herein to achieve negative differential resistance with enhanced tunneling and peak-to-valley ratio (PVR) stability. The proposed structures are of the form n+–p−–p+ (S2) and n+–[p−–n+]–p−–p+ (S1) with different electrodes made of parallel graphene nanoribbon and graphene sheet (S2) or bilayer graphene (S1). The results of the simulations show a PVR of 3–3.5 depending on the geometry of the structure, with a maximum current of 10 μA. Also, robust PVR values in the range of 1.2–1.5 are obtained for these structures for a wide range of dimensions. An approximate analytical model for the I–V curve under the assumption of a vertical van der Waals bonding stacked structure as equivalent to the complex horizontal channel is introduced.