Solar-Blind Enhanced Dual-Band Ultraviolet Photodetector.

We present a dual-band ultraviolet photodetector based on a β-Ga₂O₃/(AlxGa₁ ₋ x)₂O₃/GaN heterojunction, which not only achieves solar-blind ultraviolet enhancement but also distinguishes different ultraviolet wavelengths (λ ≤ 270 nm and λ > 270 nm) by utilizing the varying current relaxation rates after exposure to different wavelengths of light. The introduction of the (AlxGa1-x)₂O₃ barrier layer significantly reduces the reverse leakage current of the heterojunction device. Meanwhile, under solar-blind ultraviolet irradiation, the self-trapped holes generated in the Ga₂O₃ material enhance the junction electric field and induce carrier tunneling, resulting in photogenerated current gain and significantly improving the device's photodetection performance in the solar-blind ultraviolet range. Under a -20 V bias, the device achieves a photocurrent gain of 2033, a photoresponsivity of 900 A/W, and a detectivity of 2.55 × 10¹³ Jones under solar-blind ultraviolet illumination. To address the pronounced persistent photoconductivity observed under solar-blind UV illumination, suppression is achieved by combining ultraviolet illumination with circuit interruption, significantly reducing the current relaxation time. Furthermore, a novel method for achieving dual-band ultraviolet detection is proposed, which utilizes the difference in relaxation rates of the device current under illumination at different ultraviolet wavelengths to enable discrimination between solar-blind and long-wave ultraviolet light.