Emulation of optical and electrical synaptic functions in MoS2/SnSe2 van der Waals heterojunction memtransistors

The simulation of advanced synaptic functions of the human brain by electrical devices could be an effective strategy towards constructing high-efficiency neuromorphic systems. Two-dimensional (2D) materials are promising candidates in fabrication of optoelectronic devices due to their excellent photoelectric performances. Herein, opto-electronic synapses based on layered MoS2/SnSe2 van der Waals heterojunction (vdWH) memtransistors have been investigated. It can be observed that the typical synaptic functions, such as excitatory/inhibitory postsynaptic current (EPSC/IPSC), long-term potentiation/depression (LTP/LTD), paired-pulse facilitation/depression (PPF/PPD), as well as the transition from short-term memory (STM) to long-term memory (LTM) are realized using both electrical and optical pulses as input signals. In addition, the time constant for PPF under optical pulses was 3.91 s, which was comparable with the response times of biological neural synapses. So the MoS2/SnSe2 memtransistor could work as an electronic synapse in future artificial neural networks, inspiring the implementation of 2D materials for neuromorphic computation.