Interfacial work function mismatch driven giant tunneling electroresistance in Sc2CO2/Al2S3 van der Waals ferroelectric tunnel junctions

Two-dimensional van der Waals ferroelectric heterostructures hold great promise for high-performance ferroelectric tunnel junctions (FTJs) due to their atomic-scale thickness and switchable polarization. Here, we report a first-principles study of the Sc2CO2/Al2S3 heterostructure, which demonstrates a switchable semiconductor–metal transition driven by ferroelectric polarization reversal. This transition stems from a dramatic modulation of the interfacial work function difference, from 0.067 eV in the P↑↑ state to 3.24 eV in the P↓↓ state. The large work function mismatch induces strong interlayer charge transfer, closing the bandgap and enabling metallic conduction. Non-equilibrium Green's function transport calculations reveal that a corresponding FTJ achieves an ultrahigh tunneling electroresistance ratio of 6.70×105%. Our work identifies polarization-controlled interfacial work function engineering as a potent mechanism for achieving giant switching effects in low-dimensional ferroelectric devices.