A synaptic memristor based on two-dimensional layered WSe₂ nanosheets with short- and long-term plasticity

Neural synapses with diverse synaptic functions of short- and long-term plasticity are highly desired for developing complex neuromorphic systems. A memristor with its two terminals serving as pre- and post-neurons, respectively, can emulate two neuronal-based synaptic functions. In this work, multilayer two-dimensional (2D) layered WSe₂ nanosheets are synthesized by a salt-assisted chemical vapor deposition (CVD) method. Two-terminal memristors with a planar structure are fabricated based on the CVD-grown triangular WSe₂ nanosheets. The fabricated devices exhibit typical bipolar nonvolatile resistive switching behaviors with a high current ON/OFF ratio of up to 6 × 10³ and good retention and endurance properties, suggesting good stability and reliability of the WSe₂-based memristors. Furthermore, the developed memristors demonstrate synaptic functions of short- and long-term plasticity (STP and LTP), as well as a transition from STP to LTP by applying consecutive pulse voltages. Moreover, the WSe₂-based memristors exhibits biological synaptic functions of long-term potentiation and depression, and paired-pulse facilitation. Thus, our 2D WSe₂ nanosheet based memristors not only exhibit stable and reliable nonvolatile resistive switching behaviors, but also show potential applications in mimicking biological synapses.