A Bias‐Tunable Multispectral Photodetector Based on a GaN/Te <i> _x </i> Se _1‐ <i> _x </i> Homo‐Type Heterojunction with a Unidirectional Barrier

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_xSe_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 10⁵. 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 × 10¹¹ 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 × 10⁹ 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.