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

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.