Short-Wave Infrared Waveguide-Integrated PhotodetectorBased on Transfer-Free, Scalable Two-Dimensional Bismuth

Abstract Silicon photonic integrated circuits with two-dimensional (2D) materials have great potential for developing short-wave infrared (SWIR) optoelectronics. However, achieving high-performance waveguide-integrated photodetectors remains challenging because of the need to preserve the properties of 2D materials throughout their transfer and fabrication. To overcome this limitation, we demonstrate a SWIR waveguide-integrated 2D bismuth (Bi) photodetector developed using low-temperature pulsed laser deposition in the back-end of CMOS silicon device fabrication. Benefiting from prepatterning and direct growth processes, the thin Bi film and silicon waveguide are well-integrated, exhibiting an absorption coefficient of ∼2 dB·μm–1 at 2200 nm wavelengths. The fabricated photodetector exhibits a high responsivity of 185.3 mA·W–1 and a low dark current of 201.4 nA. The study establishes a waveguide-integrated, wafer-scalable, CMOS-compatible photodetector, with potential applications in sensing and spectroscopy in the SWIR spectrum.