Experimental and numerical demonstration of threshold voltage asymmetry and synaptic plasticity in MoS2 transistors

Thanks to their advanced tunable electrical properties, two-dimensional materials have emerged as a promising platform for neuromorphic computing, offering unique flexibility and scalability. In this work, we report the fabrication and experimental characterization of MoS2-based transistors exhibiting counterclockwise hysteresis and synaptic plasticity. Our devices demonstrate multilevel conductivity modulation under pulsed excitation, and a pronounced dependence of the threshold voltages on the sweep rate of the applied gate signal. An in-house physics-based numerical simulator is exploited to rationalize the measured hysteresis and the frequency-dependent behavior, providing further insights into the underlying memristive mechanism, i.e., the delayed migration of oxygen ions. Moreover, simulations reveal that ion migration governs the observed plasticity, enabling control of current modulation through pulse duration. These findings establish the relevance of ionic dynamics in shaping device performance and highlight the potential of MoS2-based transistors for artificial neural network hardware.