Photomultiplication-Type β-Ga₂O₃ Solar-Blind Photodetector with Excellent Capability of Weak Signal Detection and Anti-Interference DUV Imaging

Achieving both low noise current and high photoconductivity gain in photodetectors (PDs) is essential for weak signal detection, but this remains a significant challenge in the state-of-the-art PDs. We fabricated highly sensitive solar-blind PDs on C-N co-doped β-Ga₂O₃ films with an extremely low dark current (10⁻¹³ A) and noise current (10⁻¹³ A Hz^−1/2), an extremely high photoresponsivity and external quantum efficiency (≈5.2 × 10⁵ A W⁻¹ and 2.6 × 10⁸%), a high 254 nm/280 nm rejection ratio (160), good transient photo-response characteristics and a wide linear dynamic range, exhibiting excellent capabilities of anti-interference deep-ultraviolet (DUV) imaging and optical communication. The extremely low noise current is attributed to the trapping of holes through deep-acceptor energy levels and weak electron-phonon scattering from C and N impurities. A photomultiplication mechanism is proposed and clarified by collective excitation of trapped holes and photogenerated carriers, which is triggered and amplified by impact ionization under strong electric fields arising from the external bias and photoinduced electric fields. This work presents a solution for the development of high-performance β-Ga₂O₃-based solar-blind PDs with DUV detection accuracy and weak signal detectivity, and paves the way for the evolution of DUV PDs applications in weak signal detection, anti-interference imaging, and optical communication.