Advances in GaN Nanowire-Based Optoelectronic Devices

One-dimensional GaN nanowires and their ternary alloys have developed from a structurally attractive wide-bandgap semiconductor architecture into a versatile platform for optoelectronic devices, neuromorphic functions, and emerging system-level applications. Their significance lies not only in the miniaturization of GaN devices, but also in the way the one-dimensional geometry reshapes strain relaxation, defect propagation, carrier transport, surface interaction, heterostructure design and optical confinement. Major progress in GaN nanowire-based optoelectronics is systematically discussed here, spanning growth strategies to practical applications. Particular attention is given to both top-down and bottom-up fabrication approaches, with emphasis on how growth pathways determine nanowire morphology, crystal quality, interface characteristics and device integration. Recent advances in photodetectors, light-emitting diodes and lasers are summarized. In addition, expanding applications in artificial synapses, image recognition, brain-inspired computing, wearable systems and solar water splitting further demonstrate that GaN nanowires are evolving from single-function device elements into multifunctional material platforms. Finally, forward-looking insights are provided into the challenges and future development of GaN nanowires. For brain-inspired computing, the most meaningful progress will come from array-level demonstrations, circuit-compatible architectures, and task-oriented evaluation under realistic signal conditions. GaN nanowires should be viewed not simply as one-dimensional versions of planar GaN, but as structurally reconfigurable and interface-rich building blocks capable of connecting light detection, emission, memory, computation, mechanical sensing and chemical energy conversion.