Photo-synaptic Memristor Devices from Solution-processed Ga2O3 Thin Films

Hardware integration with biological synaptic function is the key to realizing brain-like computing. Resistive Random Access Memory (RRAM), with a similar structure to biological synapses, are important candidate for the simulation of biological synaptic function. In this work, Ga₂O₃ film as a functional layer of RRAM is prepared by the solution method, and an RRAM-based photo-synaptic device with an Ag/Ga₂O₃/Si structure is constructed subsequently. The device exhibits excellent bipolar resistive switching characteristics, with the merits of a large storage window and long retention time. Furthermore, the devices generated excitatory postsynaptic currents (EPSC) and paired-pulse facilitation (PPF) behaviors under light pulse stimulation, enabling the simulation of synaptic plasticity. The transformation of synaptic behavior from short-term memory (STM) to long-term memory (LTM) is achieved by observing the spike-duration dependent plasticity (SDDP), spike-intensity dependent plasticity (SIDP), spike-number dependent plasticity (SNDP) and spike-rate dependent plasticity (SRDP) characteristics of photonic synapses under different conditions. The device also simulates the process of successive “learning-forgotten-remembering”, revealing that RRAM-based photonic synapses have great potential in the fields of artificial visual perception and memory storage.