Negative Differential Resistance in van der Waals Heterostructures Due to Moiré-Induced Spectral Reconstruction

Formation of moiré superlattices is common in van der Waals heterostructures as a result of the mismatch between lattice constants and misalignment of crystallographic directions of the constituent two-dimensional crystals. Here we discuss theoretically electron transport in a van der Waals tunneling transistor in which one or both of the electrodes are made of two crystals forming a moiré superlattice at their interface. As a proof of concept, we investigate structures containing either an aligned graphene/hexagonal boron nitride heterostructure or twisted-bilayer graphene and show that negative differential resistance is possible in such transistors and that this arises as a consequence of the superlattice-induced changes in the electronic density of states and without the need for momentum-conserving tunneling present in high-quality exfoliated devices. We extend this concept to a device with electrodes consisting of aligned graphene on α-In2Te2 and demonstrate negative-differential-resistance peak-to-valley ratios of approximately 10.