Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbOx

TL;DR

This study investigates how different reactive metal electrodes influence the switching behavior of NbOx-based devices, revealing how metal-oxide interlayers affect device stability and response, which aids in designing more reliable resistive/threshold switches.

Contribution

It demonstrates the impact of various reactive metal electrodes on NbOx device switching, highlighting the role of metal-oxide interlayers and providing insights for device engineering.

Findings

Nb and Ti electrodes yield symmetric threshold switching

Cr electrodes produce asymmetric hysteresis windows

Ta and Hf electrodes show threshold-memory response

Abstract

Reactive metal electrodes (Nb, Ti, Cr, Ta, and Hf) are shown to play an important role in controlling the volatile switching characteristics of metal/Nb2O5/Pt devices. In particular, devices are shown to exhibit stable threshold switching under negative bias but to have a response under positive bias that depends on the choice of metal. Three distinct responses are highlighted: Devices with Nb and Ti top electrodes are shown to exhibit stable threshold switching with symmetric characteristics for both positive and negative polarities; devices with Cr top electrodes are shown to exhibit stable threshold switching but with asymmetric hysteresis windows under positive and negative polarities; and devices with Ta and Hf electrodes are shown to exhibit an integrated threshold-memory (1S1M) response. Based on thermodynamic data and lumped element modelling these effects are attributed to the formation of a metal-oxide interlayer and its response to field-induced oxygen exchange. These results provide important insight into the physical origin of the switching response and pathways for engineering devices with reliable switching characteristics.