Enhanced UV photodetection of Ag-decorated GaN/Si heterojunctions prepared by pulsed laser ablation in liquid and hydrothermal deposition.

Abstract

In this study, GaN nanoparticles were synthesized by pulsed laser ablation in liquid (PLAL) followed by hydrothermal deposition. Different AgNO₃ concentrations were comparatively investigated to determine the optimum amount for fabricating the Ag-decorated GaN/Si UV photodetector. Among the investigated amounts, the sample prepared using 0.01 g AgNO₃ exhibited the highest figure of merit and was therefore selected for detailed characterization and device fabrication. Ag diffraction peaks and the hexagonal wurtzite GaN phase were confirmed by XRD investigation. Optical measurements showed a bandgap of 3.37 eV. FESEM and AFM analyses revealed a uniform distribution of Ag nanoparticles, indicating successful surface modification. Based on these improved physical properties, the Ag-decorated GaN/Si heterojunction photodetector was fabricated, exhibiting enhanced responsivity, detectivity, and overall UV-photodetection performance. The Ag-decorated device exhibited improved electrical performance and higher responsivity and detectivity at 380 nm compared with the pure GaN/Si device. The ideality factor (n) was reduced to 1.6 for the Ag-decorated GaN/Si heterojunction device. The faster response of the Ag-decorated GaN/Si device demonstrates its potential for fast-switching optoelectronic applications.