One nanometer HfO$_2$-based ferroelectric tunnel junctions on silicon

TL;DR

This paper demonstrates 1 nm thick Zr-doped HfO₂ ferroelectric tunnel junctions on silicon, achieving record electroresistance and high tunnel current, promising for high-speed, nonvolatile memory applications.

Contribution

It introduces CMOS-compatible, ultrathin Zr:HfO₂ ferroelectric barriers with record electroresistance and high tunnel current, advancing ferroelectric tunnel junction technology.

Findings

Record 19000% electroresistance in HfO₂ FTJs.

Large tunnel current (> 1 A/cm²) at low voltage.

Ultrathin 1 nm ferroelectric barrier on silicon.

Abstract

In ferroelectric materials, spontaneous symmetry breaking leads to a switchable electric polarization, which offers significant promise for nonvolatile memories. In particular, ferroelectric tunnel junctions (FTJs) have emerged as a new resistive switching memory which exploit polarization-dependent tunnel current across a thin ferroelectric barrier. Here we demonstrate FTJs with CMOS-compatible Zr-doped HfO$_2$ (Zr:HfO$_2$) ferroelectric barriers of just 1 nm thickness, grown by atomic layer deposition on silicon. These 1 nm Zr:HfO$_2$ tunnel junctions exhibit large polarization-driven electroresistance (19000$\%$), the largest value reported for HfO$_2$-based FTJs. In addition, due to just a 1 nm ferroelectric barrier, these junctions provide large tunnel current (> 1 A/cm$^2$) at low read voltage, orders of magnitude larger than reported thicker HfO$_2$-based FTJs. Therefore, our proof-of-principle demonstration provides an approach to simultaneously overcome three major drawbacks of prototypical FTJs: a Si-compatible ultrathin ferroelectric, large electroresistance, and large read current for high-speed operation.