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

摘要

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 formn(+)-p(-)-p(+)(S2) andn(+)-[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 mu A. 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 theI-Vcurve under the assumption of a vertical van der Waals bonding stacked structure as equivalent to the complex horizontal channel is introduced.