Unconventional Multimodal Switching in Single-Crystalline Nanowire Channel ECRAM.

Electrochemical random-access memory (ECRAM) devices are promising synaptic elements for neuromorphic computing due to their uniform and tunable programmability. However, despite growing interest in ECRAM devices, studies have primarily focused on devices with amorphous or polycrystalline tungsten oxide (WO) films, leaving the impact of single-crystalline materials in oxygen-based ECRAMs largely unexplored. This work reports the first realization of single-crystalline hexagonal tungsten oxide (h-WO) nanowire (NW) based ECRAM device. Leveraging the high crystallinity and distinct atomic structure of h-WO NWs, the device exhibits significantly enhanced symmetry in conductance modulation, a key metric for synaptic emulation. More strikingly, a novel lateral switching mode emerges under specific configurations, accompanied by an unexpected conductance surge during relaxation, resembling neuronal integration and activation functions. A mechanism attributed to the electrode-NW interface properties is proposed to explain this behavior. These findings not only reveal a previously unexplored aspect of ECRAM switching physics, but also expand the functional potential of ECRAMs through fundamental material innovation.