Ultra-scaled 2D resonant tunneling diodes (RTDs), with dimensions of 2 nm×4.55 nm and 2 nm×5.3 nm, exhibiting negative differential resistance (NDR) are proposed. Zigzag graphene nanoribbons (ZGNRs) are used as base material. Boron nitride (BN) decoration is utilized to open a gap in ZGNR energy bandstructure. Within the framework of nonequilibrium green’s function (NEFG) and tight binding (TB) approximated Hamiltonian the device operation of proposed RTDs is investigated. The effect of well and barrier length modulation on the device figures is studied. Results show that extremely small changes, in the order of few angstroms, in the well or the barrier dimensions translates to significant change in device figures.