Modulation of Conductive Filaments in Ag/Cu₂S/SiO₂/W Memristor

For the active-metal/insulator/metal memristor, the reversible formation and annihilation of metallic filaments critically influence the performance. However, efficient methods of controlling filament nucleation sites and growth dimensions remain elusive, particularly for amorphous oxides. In this work, an ionic conductive Cu₂S layer is introduced to the Ag/SiO₂/W memristor to restrict the formation pathways of metallic filaments. Localized Cu₂S phase transition (from the monoclinic phase to the hexagonal phase) and columnar grain boundaries are identified as preferred nucleation and growth sites during SET. This approach suppresses random filament growth within the amorphous SiO₂ layer, overcomes the challenge of high-resistance state recovery, and significantly improves the controllability of filament formation and annihilation. As a result, the Ag/Cu₂S/SiO₂/W memristor demonstrates a stable cycling endurance and a switching ratio of up to 10⁶. This work provides experimental insight into controlling the formation of conductive filaments for high-performance memristors.