Investigation of the Resistive Switching Mechanism in Li_xNbO₂ Memristors

A complete understanding of the origin of resistive switching in memristors is necessary for implementation into neuromorphic computing applications. However, the resistive switching of memristors is typically attributed to a complex combination of processes (e.g., redox reactions, ionic transport, phase changes, etc.) post an electroforming step, which limits tunability and scalabilitiy of the device. Li_xNbO₂ analog memristors circumvent the electroforming step and demonstrate a promising new mechanism wherein the diffusion of Li⁺ ions enables precise control of the resistive states [1]. Here we utilize synchotron-based x-ray spectroscopy techniques to examine the electronic strucure of Li_xNbO₂ memristors. We employ x-ray absorption spectroscopy (XAS) across the active to observe variations in the Li content. Additionally, we investigate the origin of non-volatility by probing the buried interface at the metal contacts via hard x-ray photoelectron spectroscopy (HAXPES). This work opens a new avenue of methodology for illuminating resistive switching mechanisms in memristors from a fundamental perspective.

[1] S.A. Howard et. al., APL Mater. 7, 071103 (2019)