Ultranarrow-Band DUV Detection Enabled by Plasmonic Coupled Nanohole Arrays in AlN/GaN Superlattices

Precise signal identification in solar-blind deep-ultraviolet (DUV) detection critically relies on high-performance devices with exceptional spectral selectivity. A novel strategy is proposed to significantly enhance DUV photodetector performance by integrating plasmonic nanohole engineering with ultrashort-period AlN/GaN superlattices for ultranarrow-band detection. Simulations indicate that Al-filled nanoholes with a diameter of 230 nm and a sidewall angle of 60° can yield up to a 31-fold enhancement of the localized electric field at the Al-nanohole sidewall interfaces compared to nanohole structures without Al. Accordingly, metal–semiconductor–metal (MSM) photodetectors incorporating Al-filled hexagonal nanohole arrays within the AlN/GaN superlattice absorption layers were fabricated. The designed three-dimensional architecture, which provides an increased interaction area and effective optical path length, achieves a remarkable peak responsivity of 42.6 mA/W at 238 nm under a 15 V bias. This represents a 4.5-fold improvement over planar reference devices. Furthermore, the devices exhibit ultranarrow spectral selectivity with a full-width at half-maximum (fwhm) of only 19 nm, attributed to the precise spectral alignment between the localized surface plasmon resonance (LSPR) and the superlattice absorption profile. This novel combination of plasmonics and nanohole superlattices offers a promising avenue for high-performance DUV photodetectors in applications requiring highly selective spectral operation.