High-Performance Self-Driven Ultraviolet Photodetector Based on Sol–Gel Derived NiO/Sn:Ga ₂ O ₃ p–n Junction

Ga2O3-based self-driven solar-blind ultraviolet (SBUV) photodetectors have attracted considerable attention for their promising applications in military, civil, and industrial fields. However, conventional manufacturing methods for high-performance Ga2O3 photodetectors typically require complex processes and high costs, thereby severely constraining their practical applications. In this work, we demonstrate a high-performance NiO/Sn:Ga2O3 p–n junction SBUV photodetector fabricated by a low-cost sol–gel method. The device exhibits an excellent photocurrent response under zero bias, with a responsivity (R) of 47.89 mA/W and a detectivity (D*) of 4.60 × 1011 Jones at 240 nm. These performance parameters are remarkably higher than those of the Ga2O3 device (R = 7.91 mA/W, D* = 0.61 × 1011 Jones) and the NiO/Ga2O3 device (R = 19.36 mA/W, D* = 2.61 × 1011 Jones). Under weak light illumination (P255 nm = 0.53 μW/cm2), the R and D* of the NiO/Sn:Ga2O3 SBUV photodetector reach 150.6 mA/W and 1.33 × 1012 Jones, respectively, which are superior to most reported NiO/Ga2O3-based photodetectors. The ultrahigh performance can be attributed to the enhanced built-in electric field at the NiO/Sn:Ga2O3 p–n junction interface and the improved electrical transport properties of the Sn:Ga2O3 layer. This study provides a feasible route toward the development of low-cost, high-performance Ga2O3-based self-driven UV photodetectors.