Device Engineering of Bismuth-Based Chalcogenides for Low-Noise, Near-Infrared Photon-Counting

Near-infrared (NIR) photodetection is critical for both military and civilian applications. However, conventional NIR detectors often suffer from high dark currents and reliance on cryogenic cooling, limiting their use in demanding environments. To overcome these challenges, we developed high-quality bismuth-based chalcogenide bilayer films using a cost-effective solution process and fabricated the corresponding photodiodes. The resulting silver bismuth sulfide/antimony bismuth sulfide bilayer photodetectors possess the metrics of both low dark current of antimony bismuth sulfide-based devices and the broad spectral response of silver bismuth sulfide-based photodetectors, exhibiting a synergistic enhancement in performance. The optimized photodiodes achieve an extended detection range up to 1250 nm while demonstrating excellent performance metrics, including ultralow dark current and noise, high sensitivity, fast response and outstanding stability. Moreover, these devices show promising potential for NIR photon-counting and optical communication, offering a viable pathway toward high-performance near-infrared photodetectors working at room temperature.