An Image Detection-Memory-Recognition Artificial Visual Unit Based on Dual-Gate Phototransistors

Optoelectronic synapses integrating sensing-memory-processing functions have great advantages in neuromorphic computing for visual information processing and complex learning, recognition, and memory in an energy-efficient manner. Herein, a light-induced bidirectional response is demonstrated in the proposed WSe2/MoS2 junction field-effect transistor (JFET) with an extra Ge back gate. The WSe2/MoS2 JFET exhibits high responsivity and detectivity owing to effective modulation by the top junction and back dielectric gates. The unique bidirectional photoresponse and interfacial state storage properties of the device result in significant synaptic excitatory effects under visible light stimulation and remarkable synaptic inhibitory effects under infrared illumination. Optical storage with visible light and optical erasure with infrared light can be achieved in the device based on its synaptic behavior. The conductance changes under different types of illumination can be used to mimic the weight update in a neural network for image recognition. A high accuracy exceeding 98% was achieved in handwritten digit recognition. This visible and infrared dual-band phototransistor, which integrates image perception, memory, and recognition functionalities, provides a promising solution for self-driving, surveillance, computer vision, and biomedical imaging applications.