A Carbon‐Introduced Single Layer GaN Artificial Optoelectronic Synapse for Human Action Recognition and Spatio‐Temporal Encoding

To realize real‐time, device‐based cognitive tasks, there is an urgent need to develop high‐performance optoelectronic synapse devices that integrate perception and storage functions. While optoelectronic synapse devices with various structures such as hybrid‐dimensional or heterostructure expand the functional design space, applicable neuromorphic vision hardware requires material platforms that are scalable, manufacturable and reproducible. This study demonstrates an array‐level single layer GaN synapse fabricated by conventional semiconductor processes. Although the direct bandgap of GaN is unfavorable for the persistent photoconductivity (PPC) effect, it can be obtained through intentionally introduced carbon atoms in GaN film by adjusting the growth parameters and optimizing the Ti/Al–GaN interface. The optoelectronic synapse device exhibits repeatable excitatory postsynaptic current (EPSC), paired‐pulse facilitation (PPF), tunable short‐term plasticity (STP) and long‐term potentiation (LTP). The carrier capture and release at carbon‐related deep‐level defects enable exceptional device uniformity and stability. The STP characteristics of this device are employed for human action recognition, enabling efficient processing of dynamic temporal signals. Moreover, array‐level LTP is used for spatio‐temporal encoding, demonstrating stable signal storage. This work establishes a concise, stable, and CMOS‐compatible fabrication strategy for optoelectronic synapse arrays, presenting a reliable and scalable hardware platform for future brain‐inspired perception and intelligent recognition systems.