Engineering oxygen vacancies via Ar+ ion implantation in single-layer HfO2 self-rectifying memristors

Metal-oxide self-rectifying memristors (SRMs) are promising candidates for selector-free high-density three-dimensional (3D) computing-in-memory (CIM) systems, yet the role of oxygen vacancy (OV) states in governing the self-rectifying memristive characteristics remains poorly understood. Here, argon ion (Ar+) implantation is employed as a post-deposition defect engineering strategy to regulate OV defect states in Ta/HfO2/Pt SRMs. The effect of the OV concentration and distribution on self-rectifying memristive performance is clarified. The optimized implantation condition (1 × 1015 ions/cm2, 15 keV) yields a rectification ratio (RR), nonlinearity (NL), and on/off ratio exceeding 105, as well as excellent switching uniformity. The device can be repeatedly programmed for more than 104 cycles and has robust retention for more than 104 s and a calculated scalability of 32 Gbit. Comparative experiments confirm that the Ar+ ion implantation engineered OV profile, featuring a higher concentration and an ordered OV distribution near the Ta electrode and a lower OV concentration near the Pt electrode, can balance trap-assisted transport and interfacial barrier preservation, contributing to at least a 100 times enhancement in RR, NL, and the on/off ratio. These findings establish a systematic understanding of SRM performance modulation mechanisms and provide a rational design approach for selector-free memristive devices toward scalable CIM applications.