Optically excited artificial synapse based on α-In2Se3 FETs on Ta2O5

Abstract

Materials and devices for artificial synapses are being increasingly investigated owing to their promise for brain-inspired computing. Here, we demonstrate an optoelectronic synapse with a light-modulated memory capability in back-gated ferroelectric channel field-effect transistors made of multi-layered 2D α-In2Se3 on Ta2O5. The optical tunability is achieved by exploiting the frequency of the optical signal in vertically stacked layers of In2Se3, which generates a unique persistent photoresponse due to trapping at the In2Se3/Ta2O5 interface. For the 527 nm source wavelengths at intensities of 15 mW cm−2 the In2Se3-FET exhibits a high photoresponsivity at 850 AW−1. These devices can replicate synaptic functions such as photo-induced short-term memory, long-term memory and paired-pulse facilitation—all via optical modulation. We also demonstrate common memory effects that occur in the brain, such as memory loss and memory transitions that depend upon the stimulation rate (i.e., the interval between stimulation pulses). These demonstrations provide a simple and effective strategy for fabricating light-stimulated synaptic transistors with memory and learning abilities which are attractive for building vision-inspired neuromorphic systems.