Ultrahigh TER ratios and nonvolatile behavior in dual-polarized GaAs/In2Se3 heterostructures: A first-principles study

Ferroelectric tunnel junctions (FTJs) have great potential for high-density nonvolatile memory applications. Achieving high performance of FTJs in low-dimensional materials is still challenging. Here, we systematically investigate the structural and electronic properties of dual-polarized GaAs/In2Se3 heterostructures by first-principles calculations based on density functional theory. It is shown how the interplay of polarization and stacking geometries of the monolayers can lead to heterojunctions with vastly different electronic properties. The band alignment in the heterojunctions is effectively governed by the ferroelectric polarization, changing from type-II (P↑ state) to type-III (P↓ state) in a self-doped P–N contact. Particularly, it is demonstrated that ferroelectric heterostructures can achieve a remarkably high tunneling electro-resistance ratio of 5.06 × 1014% at zero bias and up to 108% under a bias of ±0.15 V. This characteristic behavior is strongly related to the interfacial charge redistribution and to the ensuing electric polarization. Our findings not only unravel the role of polarization on the electronic properties but also open perspectives for nonvolatile FTJs in 2D ferroelectric semiconductors.