Unraveling the dynamics of conductive filaments in MoS2-based memristors by operando transmission electron microscopy

Advanced operando transmission electron microscopy (TEM) techniques enable the observation of nanoscale phenomena in electronic devices during operation. Here, we investigated lateral memristive devices composed of two dimensional layered MoS₂ with Pd and Ag electrodes. Under external bias voltage, we visualized the formation and migration of Ag conductive filaments (CFs) between the two electrodes, and their complete dissolution upon reversing the biasing polarity. The CFs exhibited a wide range of sizes, from several Ångströms to tens of nanometers, and followed diverse pathways: along the MoS₂ surfaces, within the van der Waals gap between MoS₂ layers, and through the spacing between MoS₂ bundles. Our method enables correlation between current-voltage responses and real-time TEM imaging, offering insights into failed and anomalous switching behaviors, and clarifying the cycle-to-cycle variabilities. Our findings provide solid evidence for the electrochemical metallization mechanism, elucidate the formation dynamics of CFs, and reveal key parameters influencing the switching performance.