Giant Tunneling Electroresistance in 2-D In-Plane Ferroelectric Tunnel Junctions Based on a α -In₂Se₃/Cd₃C₂ Heterostructure

Abstract

Ferroelectric tunnel junctions (FTJs), composed of two metallic or semiconductor leads separated by a thin ferroelectric tunnel barrier, demonstrate significant potential for nonvolatile memory devices. With the development of device miniaturization, 2-D FTJs have attracted increasing attention due to the unique characteristics of material stability, atomic thickness, and high tunnel electroresistance (TER) ratio. In this work, a 2-D in-plane van der Waals (vdW) FTJ constructed using a In2Se3/Cd3C2 heterostructure is designed, and its electron transport properties have been investigated based on density functional calculations combined with a nonequilibrium Green’s function (NEGF) technique. The results demonstrate that a TER ratio of 106% is achieved due to the change from Schottky- to Ohmic-type contact at the In2Se3/Cd3C2 interface accompanied by ferroelectric polarization reversal. Meanwhile, the current-voltage (I–V) characteristics at low bias voltages indicate significant amplitude differences between currents under different polarization states. The TER can be stably maintained above 106%, indicating two ideal states “0” and “1” for data storage. The mechanism for the Schottky to Ohmic switching is explained by different charge transfers between the contacted surfaces of the two materials under different polarization directions, which are further controlled by the work functions of them. Consequently, work function engineering offers a promising method for constructing 2-D ferroelectric vdW heterostructures and FTJs, which has promising application potential in nanoscale high-density ferroelectric memory devices.