A Vertical Hybrid van der Waals Ferroelectric Material for Nonvolatile Memory

Two-dimensional (2D) ferroelectric materials can form an atomically thin dipole layer that can influence the electronic properties of a hybrid layered structure composed of a ferroelectric layer and a transition-metal dichalcogenide (TMDC). In this work, we investigate the ability of a 2D ferroelectric material, CuBiP₂Se₆, to transition between two dipolar states as a potential nonvolatile memory component. We propose a 2D heterostructure as a tunable p–n junction composed of a TDMC layer and a 2D ferroelectric layer, wherein the TMDC layer acts as the electron acceptor and CuBiP₂Se₆ acts as the electron donor across the heterostructure. Using density functional theory, we find that the ferroelectric-MoSe₂ bilayer transitions between an indirect type II bandgap and a direct type I bandgap, as a function of the change in the direction of the electric dipole in the ferroelectric layer. The electric field can lock the bandgap of the bilayer in one of two states, thus operating as a switchable ferroelectric memory device. Our work presents new hybrid bilayer materials that could be used in the construction of neuromorphic components.