All‐Silicon Broadband Infrared Photodetectors With In‐Plane Photon Trapping Structures

Abstract Silicon (Si) photonics has been widely explored for many various applications, including optical communication, optoelectronic computing, spectroscopy, and image sensing. As a key component for optoelectronic signal conversion in these applications, Si‐based infrared photodetectors have attracted extensive attention. However, achieving all‐Si on‐chip photodetection in the very long‐wavelength infrared (VLWIR) range remains challenging, with broadband enhancement and improved operating temperature being pressing issues that need to be addressed. An all‐Si photodetector design is presented using in‐plane photon trapping structures (IPTS) to enhance detection efficiency and improve the operating temperature of the photodetector at the VLWIR range. The photodetector achieves a broadband enhancement of 285–575% (across 12–19 µm) and a 31% reduction in dark current. Additionally, it exhibits an impressive peak specific detectivity of 1.9 × 10¹⁰ cm Hz^1/2 W⁻¹ at 15 µm, operating at a temperature of 40 K. This study introduces a novel all‐Si optoelectronic device architecture that offers a promising solution for improving the operating temperature and sensitivity of broadband VLWIR devices, making the whole system more compact and cost‐effective.