On‐Chip Room‐Temperature Operated Short‐Wavelength‐Infrared Si:S Photodetector with a Vertical Junction

Abstract Silicon (Si)‐based photodetectors are cost‐effective, eco‐friendly, and compatible with on‐chip complementary metal‐oxide‐semiconductor (CMOS) technology. However, expanding their photoresponse into the short‐wavelength‐infrared region beyond 1.1 µm remains challenging because of the intrinsic bandgap of Si. In this study, an ion implantation sulfur‐doped Si‐based infrared photodetector featuring a blocked impurity band (BIB) structure is investigated. The detector achieves an extended sub‐bandgap infrared response up to 2 µm through impurity band transitions, facilitated by the artificial creation of a deep‐level impurity band within the Si bandgap. The device exhibited a competitive photodetection effect with a high responsivity of 107.3 mA W⁻¹ and an external quantum efficiency of 10.2%. Notably, the detector yielded an enhanced response speed with a raising time of 46 µs and a decay time of 135 µs at 1310 nm under room temperature. Finally, the versatile applications of this detector is presented in a multitude of scenarios encompassing material composition identification, multi‐band imaging, and optical communication. The proposed investigation not only proposed a method for Si‐based infrared detectors but also constituted a contribution to the advancement of silicon photonics.