Tunneling electroresistance effect and low ON-state resistance-area product in monolayer-In2Se3-based van der Waals ferroelectric tunnel junctions

For the commercialization of high-density ferroelectric tunnel junction (FTJ) arrays, achieving a large ON/OFF tunneling electroresistance (TER) ratio concurrently with a low ON-state resistance-area product (RAP) and a high endurance cycling is perhaps the greatest challenge. In this work, to decrease ON-state RAPs (the order of magnitude of MΩ.μm2) in the experimentally reported two-dimensional (2D) multilayer van der Waals (vdW) FTJs with large TER ratios, taking monolayer In2Se3 out-plane ferroelectric barrier as an example, we construct a graphene.In2Se3.Au (Gr.In2Se3.Au) FTJ to investigate the electron transport properties using first-principles quantum transport simulations. It is found that the low ON-state RAPs of < 37 Ω.μm2 can indeed be obtained in our Gr.In2Se3.Au FTJ model, but the TER ratios become also much smaller than the experimental result of 3.9 × 108 % due to low barrier asymmetry and Ohmic contacts under both polarization states. After inserting a h-BN (BN) monolayer into right-side In2Se3/Au interface, an enhanced TER effect of one order of magnitude higher with maximum TER ratio of ∼104 % and still low ON-state RAPs (< 60 Ω.μm2) can be obtained owing to reversible metallization of In2Se3 barrier and protective role of BN for ferroelectricity. Our work provides theoretical foundation for further experimental study.