Localized Surface Plasmon Resonance‐Enhanced SiC UV Photodetectors Based on Ordered Al/Al ₂ O ₃ Core–Shell Nanoparticle Arrays

4H-SiC-based ultraviolet (UV) photodetectors (PDs) are urgently required for applications in flame detection and secure communication. However, these devices are hindered by their low quantum efficiency properties and sluggish response speed. Here, a substantial enhancement in UV detection is implemented by integrating periodic triangular Al/Al₂O₃ Core-Shell Nanoparticles (NPs) Arrays into 4H-SiC metal-semiconductor-metal (MSM) PDs. The detector exhibits an extremely low dark current (5.0 × 10^-14 A) and a peak responsivity of 2.14 A W^-1, corresponding to an external quantum efficiency of 984%. A high detectivity of 1.22 × 10¹⁴ Jones is achieved under illumination of 270 nm wavelength light at 30 V, while an ultra-high response speed is obtained with a rise time of 0.74 ns and a fall time of 1.47 ns. The improvement is attributed to the coupling between the lightning rod effect at the tips of the triangular NPs within the electrostatic field and localized surface plasmon resonance (LSPR), as well as the LSPR coupling effect between NPs, which enhances the electric field of the devices and triggers a localized avalanche effect. These results highlight the wide application and potential of NPs-enhanced 4H-SiC-based UV PDs in high-speed and high-precision detection.