Basic Properties of Tungsten Oxide Anodic Memristors

Herein, the fabrication of anodically grown WO 3 memristors in a metal–insulator–metal configuration and their characterization are reported. Oxidation state analysis by X‐ray photoelectron spectroscopy confirms the formation of a thin W oxide layer predominantly in the W 4+ oxidation state. The electrochemical analysis reveals that the anodization is mainly diffusion controlled, with partial WO 3 dissolution. Further, the fabricated memristors show strong self‐rectification during the I–U sweeps, where the conduction mechanism follows a Poole–Frenkel emission for the high resistive state, while the low‐resistive state is governed by Schottky emission at the metal–oxide interface. This allows a forming‐free resistive switching mechanism, without conductive filament formation, leading to improved device stability. Memristive endurance and retention testing reveal stable switching up to 10 6 cycles, and high‐/low‐resistive‐state ratios of almost three orders of magnitude. The endurance tests reveal that the memristive devices based on anodic WO 3 are of volatile type, beneficial for mimicking short‐term synaptic plasticity required by applications in neuromorphic computing.