Short-Wave Infrared Waveguide-Integrated Photodetector Based on Transfer-Free, Scalable Two-Dimensional Bismuth
Liqiang Qi, Jiaqi Wang, Zhibin Yang, Yao Li, Rui Niu, Tianping Xu, Shuqi Xiao, Zhenping Wu, Tiegen Liu, Hon Ki Tsang, Zhenzhou ChengAbstract
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.