Controllable Resistive Switching in ReS₂ /WS₂ Heterostructure for Nonvolatile Memory and Synaptic Simulation

Memristors with nonvolatile storage performance and simulated synaptic functions are regarded as one of the critical devices to overcome the bottleneck in traditional von Neumann computer architecture. 2D van der Waals heterostructures have paved a new way for the development of advanced memristors by integrating the intriguing features of different materials and offering additional controllability over their optoelectronic properties. Herein, planar memristors with both electrical and optical tunability based on ReS₂ /WS₂ van der Waals heterostructure are demonstrated. The devices show unique unipolar nonvolatile behavior with high R_off /R_on ratio of up to 10⁶ , desirable endurance, and retention, which are superior to pure ReS₂ and WS₂ devices. When decreasing the channel length, the set voltage can be notably reduced while the high R_off /R_on ratios are retained. By introducing electrostatic doping through the gate control, the set voltage can be tailored in a wide range from 4.50 to 0.40 V. Furthermore, biological synaptic functions and plasticity, including spike rate-dependent plasticity and paired-pulse facilitation, are successfully realized. By employing optical illumination, resistive switching can also be modulated, which is dependent on the illumination energy and power. A mechanism related to the interlayer charge transfer controlled by optical excitation is revealed.