Ga ₂ O ₃ Deep-Ultraviolet Photodetectors: Materials, Device Architectures, and Performance Frontiers

Deep-ultraviolet (DUV) photodetectors operating in the solar-blind region (200–280 nm) are of critical importance for defense, space exploration, environmental monitoring, flame detection, and secure optical communication. Among ultrawide-bandgap semiconductors, gallium oxide (Ga 2 O 3 ) has emerged as a leading material platform owing to its large intrinsic bandgap, visible-blind response, high breakdown electric field, and compatibility with scalable growth technologies. This review provides a comprehensive and structured analysis of Ga 2 O 3 -based DUV photodetectors, covering nanostructured devices, metal–semiconductor–metal architectures, junction-based photodiodes, avalanche photodetectors, and field-effect-transistor-based photodetectors. Emphasis is placed on structure–property–performance relationships, underlying physical mechanisms, and key trade-offs governing responsivity, detectivity, gain, and response speed.