Liquid Metal Based Synthesis of GaN Nanosheets with Ag Nanoparticle Modification for Enhanced Ultraviolet Photodetection

In this study, we propose a liquid metal-assisted synthesis technique for high-quality two-dimensional gallium nitride (2D GaN) nanosheets and fabricate high-performance ultraviolet (UV) photodetectors based on this approach. Silver (Ag) nanoparticles (NPs) are deposited on the 2D GaN surface via magnetron sputtering to induce the localized surface plasmon resonance (LSPR), thereby enhancing the device’s optoelectronic performance. The results show that Ag NPs modification significantly improves the optical absorption of 2D GaN in the UV–visible range, enhances the collection efficiency of photogenerated carriers, and reduces surface defect states. The optimized photodetector, operating at a bias voltage of 10 V, achieves a higher photocurrent (7.32 × 10–5 A) and lower dark current (1.1 × 10–9 A), with the photocurrent-to-dark current ratio (Ilight/Idark) increasing from 102 to 104. The responsivity (Rλ) is improved from 0.749 A/W to 2.01 A/W, the external quantum efficiency (EQE) increases from 254 to 683%, and the specific detectivity (D*) enhances from 1.99 × 109 to 5.34 × 1010 Jones. Additionally, the device exhibits an ideal linear relationship between photocurrent and incident light intensity (θ ≈ 1.02), demonstrating improved stability and predictability in its photoresponse. This study highlights the critical role of nanoscale engineering in advancing UV optoelectronic device performance and provides an effective strategy for designing high-performance UV photodetectors.