Tristate Resistive Switching in Heterogenous Van Der Waals Dielectric Structures

Two dimensional (2D) materials have been used in memristors to improve and stabilize resistive switching (RS) behavior; however, most reports used large device area ( ≥ 10
⁴
μm
²
), in which currents in each resistive state may be driven by largely defective regions that are not applicable in smaller devices. Here we present the first fabrication of cross-point memristors with sizes of 5 μm ×5 μm using multilayer heterogeneous van der Waals structure. We have constructed graphene/hexagonal boron nitride/graphene (G/h-BN/G) devices using Ti and Au electrodes. The devices can show two-state or tristate operation depending on the current limitation (CL) used. Similar memristors with larger size of 100 μm ×100 μm do not show this behavior, indicating that miniaturization of 2D materials based memristors is key to achieve this performance.