Tunneling Energy and Capacitance of Twist-Controlled Graphene Double Layers Separated by Boron Nitride Barriers

We investigate dual-gated double-monolayer graphene heterostructures, consisting of two twist-controlled graphene layers separated by atomically thin hexagonal boron nitride (hBN) tunnel barriers with various thicknesses, to determine the interlayer tunneling energy and capacitance of the hBN barriers. Because the two graphene layers' crystal axes are twist-aligned throughout fabrication, we observe energy and momentum conserving resonant tunneling characterized by gate-tunable negative differential resistance. We analyze the experimental data using a single-particle tunneling model and extract interlayer tunneling energy and capacitance as a function of the barrier thicknesses.