Bias‐Tunable GaN‐Based Dual‐Mode Photodiode Integrating Self‐Powered Sensing and Synaptic Memory for Artificial Vision

ABSTRACT Artificial visual perception systems urgently require a single device that simultaneously integrates optical sensing, information processing, and memory. However, the fundamentally different operational mechanisms of photodetection and optical memory present a major challenge to their coexistence in one device. Here, a GaN‐based dual‐mode photodiode (GaN‐DM‐photodiode) switchable between self‐powered photodetector (SPPD) and optoelectronic synapse (OS) modes via bias modulation is designed and fabricated. In SPPD mode, the device exhibits a high specific detectivity ( D* ) of 1.49 × 10 ^{1 2} Jones under 465 nm illumination, along with rapid rise/decay times of 84.95/90.68 ms. In OS mode, it successfully emulates fundamental essential biological synaptic functions, including paired‐pulse facilitation (PPF), short‐term to long‐term memory (STM/LTM) transition, and “learning experience” behavior. Furthermore, circuit‐level demonstration confirms the great potential and distinct advantages of this GaN‐DM‐photodiode for practical applications. This work provides a novel strategy for integrating self‐powered optical sensing and memory functions into a single device, offering a robust foundation for the development of high‐efficiency artificial visual perception systems.