An Ultrasensitive\nBi₂O₂Se/In₂S₃ Photodetector\nwith Low Detection Limit and Fast\nResponse toward High-Precision Unmanned Driving

Abstract

The\nmachine vision utilized in unmanned driving systems\nmust possess\nthe ability to accurately perceive scenes under low-light illumination\nconditions. To achieve this, photodetectors with low detection limits\nand a fast response are essential. Current systems rely on avalanche\ndiodes or lidars, which come with the drawbacks of increased energy\nconsumption and complexity. Here, we present an ultrasensitive photodetector\nbased on a two-dimensional (2D) Bi₂O₂Se/In₂S₃ heterostructure, incorporating a homotype unilateral\ndepletion band design. This innovative architecture effectively modulates\nthe transport of both free and photoexcited carriers, suppressing\nthe dark current and facilitating the rapid and efficient separation\nof photocarriers. Owing to these features, this device exhibits a\nresponsivity of 144 A/W, a specific detectivity of 1.2 × 10¹⁴ Jones, and a light on/off ratio of 1.1 × 10⁵. These metrics rank among the top values reported for state-of-the-art\n2D devices. Moreover, this device also demonstrates a fast response\ntime of 170/296 μs and a low noise equivalent power of 0.57\nfW/Hz^1/2, attributes that endow it with ultraweak light\nimaging capabilities. Furthermore, we have successfully integrated\nthis device into an unmanned driving system, providing a perspective\non the design and fabrication of future optoelectronic devices.