Sliding Ferroelectric Tunnel Junctions

TL;DR

This paper introduces van der Waals sliding ferroelectric tunnel junctions using bilayer hexagonal boron nitride, demonstrating giant tunnelling electroresistance and potential for high-density nano-memory applications.

Contribution

It develops and analyzes vdW sliding ferroelectric tunnel junctions with ultrathin barriers, revealing how inserting 2D materials enhances ferroelectricity and achieves giant TER.

Findings

Giant TER of ~10,000% achieved in sliding FTJs.

Electrode/BNN contact electric field quenches ferroelectricity.

Insertion of 2D materials restores ferroelectricity and enhances tunnelling performance.

Abstract

Very recently, ferroelectric polarization in staggered bilayer hexagonal boron nitride (BBN) and its novel sliding inversion mechanism was reported experimentally (Science 2021, 372, 1458; 2021, 372, 1462), which paves a new way to realize van der Waals (vdW) ferroelectric devices with new functionalities. Here, we develop vdW sliding ferroelectric tunnel junctions (FTJs) using the sliding ferroelectric BBN unit as ultrathin barriers and explore their transport properties with different ferroelectric states and metal contacts via the first principles. It is found that the electrode/BBN contact electric field quenches the ferroelectricity in the staggered BBN, resulting a very small tunnelling electroresistance (TER). Inserting high-mobility 2D materials between Au and BN can restore the BBN ferroelectricity, reaching a giant TER of ~10,000% in sliding FTJs. We finally investigate the metal-contact and thickness effect on the tunnelling property of sliding FTJs. The giant TER and multiple non-volatile resistance states in vdW sliding FTJs show the promising applications in voltage-controlled nano-memories with ultrahigh storage density.