Enhanced broadband Si-based optoelectronic synapse for artificial visual applications

Abstract

Broadband sensibility and efficient image recognition are crucial for perception and memory storage in remote sensing, reconnaissance and environmental monitoring inspired by the human cognitive system. Although the amorphous silicon (a-Si) thin film is compatible to the complementary-metal–oxidesemiconductor (CMOS) technology, implementing in-sensor broadband recognition and memory based on intrinsic a-Si is still a challenge due to the band gap restrictions and the limited spectrum sensing ability. Herein, through doping of Ru (Ruthenium), optoelectronic devices based on the band engineered a-Si:Ru films have been fabricated with a silicon-oxide heterostructure, demonstrating comprehensive broadband image recognition, memory and convolutional processing simultaneously. Upon regulating the trapping and releasing of the photogenerated electron-hole pairs, the devices could mimic various synaptic functions such as excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), transition from short- to long-term potentiation, lower switching energy and adjustable photocurrent analog states. Moreover, the in-sensor broadband convolutional processing has enhanced the high recognition accuracy for multi-band visuals, indicating a significant opportunity for future neuromorphic sensory applications and advanced robot visual systems.