Tunable dynamics via Ag-ion modulation for deterministic polarity reversal in Sb2S3 memristors

Antimony sulfide (Sb2S3) memristors typically operate via a Schottky-barrier-modulated, vacancy-mediated switching mechanism, which inherently suffers from large electroforming voltages. Here, we demonstrate a deterministic resistive switching polarity reversal in Sb2S3 memristors through Ag-ion modulation. By introducing an active silver (Ag) reservoir at the top interface, this solution-based treatment serves as an effective chemical pre-forming step: it substantially reduces the initial forming voltage from −4.70 to 2.18 V (close to the subsequent SET voltage of 1.75 V) and enlarges the ON/OFF window from ∼10 to ∼103. Combining x-ray photoelectron spectroscopy, Kelvin probe force microscopy, and dynamic band modeling, we elucidate that the treatment pins the Fermi level near the conduction band, collapses the original Schottky barrier, and re-routes conduction from the native interface-type switching regime to a grain-boundary-confined Ag-filamentary electrochemical metallization mechanism. The identical polarity reversal transfers to the long-term synaptic plasticity, offering a deterministic chemical handle for designing polarity-on-demand chalcogenide neuromorphic hardware.