Solar‐Blind Enhanced Dual‐Band Ultraviolet Photodetector

ABSTRACT We present a dual‐band ultraviolet photodetector based on a β ‐Ga ₂ O ₃ /(Al _x Ga _{1 − x} ) ₂ O ₃ /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 (Al _x Ga _1‐x ) ₂ O ₃ 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 Ga ₂ O ₃ 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 × 10 ¹³ 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.