# Tunable Switching Mechanisms in HfZrO2‐Based Tunnel Junctions for High‐Performance Synaptic Arrays

## TL;DR

This paper shows how to design tunable, high-performance synaptic arrays using HfZrO2-based tunnel junctions for efficient neuromorphic computing.

## Contribution

The study introduces hybrid-switching mechanisms in HZO-based FTJs through controlled interlayer design and oxygen vacancy manipulation.

## Key findings

- Three distinct operational modes were achieved in HZO films using different electrode and interlayer configurations.
- A 42 × 42 FTJ array demonstrated uniform multi-level conductance modulation and stable VMM operations.
- Hybrid-switching FTJs offer scalable, energy-efficient hardware for in-memory computing and neuromorphic systems.

## Abstract

Strategic optimization of ferroelectric tunnel junctions (FTJs) is critical for advancing nonvolatile memory and neuromorphic computing technologies. In this work, we present a comprehensive study on materials and structural engineering to enable scalable hybrid‐switching FTJ arrays. We systematically manipulated oxygen vacancy (VO) concentrations in HfZrO2 (HZO) films through strategic choices of bottom electrodes and interfacial layers, achieving three distinct operational modes: pure ferroelectric switching, defect‐modulated switching, and combined hybrid switching. Our optimized devices demonstrate exceptional tunneling electroresistance (TER) performance: Mo bottom electrodes achieve a TER ratio of around 102, while Mo/Ti bottom electrodes attain TER to over 104. Lower‐leakage ferroelectric switching and enhanced polarization stability are observed with Mo bottom and ZrO2 interlayers, while VO‐driven resistive contributions from Ti electrodes amplify TER in hybrid devices. Utilizing these optimized parameters, we fabricated a 42 × 42 FTJ array demonstrating uniform multi‐level conductance modulation. The fabricated FTJ array was integrated into an in‐memory Vision Transformer (ViT) architecture, successfully performing stable and energy‐efficient parallel vector–matrix multiplication (VMM) operations despite device variability. This work shows that precisely engineered, large‐area hybrid‐switching FTJ arrays can provide a scalable and energy‐efficient hardware platform for next‐generation memory and neuromorphic systems.

This work demonstrates hybrid switching in engineered HZO‐based FTJs, enabled by controlled interlayer design and oxygen scavenging dynamics. The combined switching mechanism produces robust multilevel conductance states in large crossbar arrays, offering a materials‐driven pathway toward scalable in‐memory computing with enhanced tunability and stability.