Interfacial work-function engineering for giant tunneling electroresistance in a Sc2CO2/Y2CO2van der Waals ferroelectric tunnel junction.

Van der Waals ferroelectric tunnel junctions (FTJs) based on two-dimensional (2D) materials offer a promising platform for next-generation nonvolatile memory, yet achieving ultrahigh tunneling electroresistance (TER) remains a critical challenge. This work demonstrates a giant TER effect of 5.83 × 109% in a vertically stacked FTJ comprising out-of-plane ferroelectric monolayers Sc2CO2and Y2CO2. First-principles calculations and quantum transport simulations reveal that the TER originates from interfacial work-function engineering. In theP↓↓state, a substantial work-function difference (ΔW= 2.35 eV) drives significant charge transfer and yielding high conductance. Conversely, theP↓↑configuration exhibits a smaller ΔW(0.85 eV), insufficient to overcome the Sc2CO2band gap. These findings not only propose Sc2CO2/Y2CO2as an exceptional candidate for high-performance memory devices but also establish a general interfacial design strategy for achieving colossal TER in low-dimensional ferroelectric systems.