A Bias‐Tunable Multispectral Photodetector Based on a GaN/TexSe1‐x Homo‐Type Heterojunction with a Unidirectional Barrier

Abstract Multispectral detection technology captures characteristic spectral information across various wavebands, exhibiting substantial application potential. However, most currently reported multispectral photodetectors rely on intricate dual‐ or multi‐junction structures, severely limiting material thickness, doping concentration, and band alignment design, thereby impeding widespread adoption. In this study, a bias‐tunable multispectral photodetector featuring a straightforward single‐junction design is introduced. The device comprises a Te x Se 1‐ x /GaN homo‐type heterojunction with a unidirectional barrier. This structure effectively suppresses the majority‐carrier dark current, yielding a low reverse dark current of ≈10 −12 A and a high rectification ratio of up to 10 5 . By adjusting the bias polarity and magnitude, the spectral response range of the device can be broadened from ultraviolet (UV) to short‐wave infrared. Notably, the photodetection performance is exceptional: at 0 V bias, the device exhibits a responsivity of 0.25 A W −1 and a specific detectivity of 5.04 × 10 11 cm Hz 1/2 W −1 under 365 nm illumination; at −2 V bias, it achieves a responsivity of 0.58 A W −1 and a specific detectivity of 2.64 × 10 9 cm Hz 1/2 W −1 under 1060 nm illumination. Leveraging the bias‐tunable spectral response characteristic of the device, proof‐of‐concept imaging is successfully demonstrated. This research presents a simplified and economical method for fabricating multispectral photodetectors.