Solar-blind photodetectors have received increasing attention due to their widely applications in military and civil aspects. However, most of the photodetectors exhibit low detection ability for weak ultraviolet light signal, and the forewarning of weak ultraviolet radiation is important for the immune system of humans. Herein, the self-powered photodetector based on $\beta $ -Ga ₂ O ₃ /NiO heterojunction with an ultralow dark current (1.09 nA at −15 V) has been fabricated, and the synthesized platinum (Pt) nanoparticles (NPs) are used for surface modification of the device. The obtained devices with Pt NPs exhibit a large ${I}_{\text {photo}}/{I}_{\text {dark}}$ ratio of 9153, an excellent detectivity of $4.2\times 10^{9}$ Jones, an ultrahigh linear dynamic range of 79 dB, and a high responsivity of 4.27 mA/W, with respective enhancements over 4476%, 2220%, 71.7%, and 2442% compared to the pristine device, respectively. These results indicated that the device has the excellent ability for weak ultraviolet light signal detection, and the enhanced performance can be attributed to the Pt NPs, which can remarkably enhance the generation of photogenerated carriers via the formation of the local electric field and the local surface plasmon resonance effect. The experiment provides an effective method for fabricating high-performance solar-blind photodetector.

Self-powered photodetectors working in solar-blind region (below 280 nm) have attracted growing attention due to their wide applicability. Monoclinic Ga₂O₃ (β-Ga₂O₃) with excellent merits and a wide bandgap (4.9 eV) is regarded as a good candidate for solar-blind photodetector application. Self-powered photodetectors generally based on homo/heterojunction suffer from a complex fabrication process and slow photoresponse because of the interface defects and traps. Herein, we demonstrated a fabrication and characterization of a self-powered metal-semiconductor-metal (MSM) deep-ultraviolet (DUV) photodetector based on single crystal β-Ga₂O₃. The self-powered property was realized through a simple one-step deposition of an asymmetrical pair of Schottky interdigital contacts. The photocurrent and responsivity increase with the degenerating symmetrical contact. For the device with the most asymmetric interdigital contacts operated at 0 V bias, the maximum photocurrent reaches 2.7 nA. The responsivity R_λ, external quantum efficiency EQE, detectivity D*, and linear dynamic range LDR are 1.28 mA/W, 0.63, 1.77 × 10¹¹ Jones, and 23.5 dB, respectively. The device exhibits excellent repeatability and stability at the same time. Besides, the device presents a fast response speed with a rise time of 0.03 s and a decay time of 0.08 s. All these results indicate a promising and simple method to fabricate a zero-powered DUV photodetector.