Highly transparent solid-state artificial synapse based on oxide memristor

A synaptic device based on memristive switching that functionally mimics a biological synapse uses an electronic synapse (like a wire) to realize neuromorphic computing. Conventional two-terminal based memristors can be used for high-performing synaptic devices; however, these memristors suffer from several shortcomings (e.g. reproducibility) due to unstable filament formation during the switching process. Here, a solid state electronic synaptic device based on WO3/NiO/FTO heterostructures has been demonstrated. The typical artificial synaptic device behavior was observed from the current-voltage characteristics under consecutive voltage sweeps which revealing clockwise hysteresis. The schematic of the working mechanism of the solid-state electronic synapses revealed that the presence of the NiO layer, working as a carrier selective layer, enhances the trapping of charge carriers and thereby improves the stability and switching uniformity. In addition, from the analysis on the carrier transport mechanisms, the trap-filled assists space-charge-limited-current conduction mechanism is found to be dominant. This work will be an important step forward towards the realization of low-cost and transparent synaptic behavior.