Pulse-shaped femtosecond-laser-modified Si:S photodetector for ultrawide-spectrum focal plane arrays and weak-light detection

High-performance Si photodetectors featuring an ultrawide spectral range can be realized through femtosecond (fs)-laser modification, enabling their broad application in focal plane arrays (FPAs) for artificial intelligence and complex operational scenarios. However, laser-induced surface inhomogeneity and elevated dark currents reduce the signal-to-noise ratio of FPAs in image detector arrays. To address these challenges, a pulse-shaping technique is employed here to precisely control light-matter interactions during laser modification. This approach not only improves the uniformity of surface microstructures but also significantly suppresses dark currents. The optimized device exhibits high responsivity across the visible to near-infrared spectrum, with a peak responsivity of 164.17 A·W^-1 at -2.5 V. Notably, the photodetector demonstrates exceptional weak-light detection capacity at room temperature owing to its record-high specific detectivity of 1.71 × 10¹⁴ Jones, surpassing that of all previously reported Si-based photodetectors. These results highlight substantial advancements in the application of fs-laser-modified Si photodetectors, underscoring their potential in fields such as autonomous driving, weak-light detection, and medical monitoring.