Highly Polarization-Sensitive Narrowband Near-Infrared Photodetection by All-Silicon Embedded Plasmonic Hot Electron Devices

Polarization-sensitive narrowband near-infrared photodetection plays a crucial role in applications, such as astronomy, target identification, and environmental sensing. Plasmonic hot electron devices based on the internal photoemission effect offer a cost-effective and scalable alternative for achieving miniaturized, polarization-sensitive narrowband all-silicon photodetection, enabled by complementary metal-oxide-semiconductor-compatible fabrication and filterless configurations. However, their responsivity and polarization sensitivity remain insufficient for practical applications. Here, we report a highly polarization-sensitive, narrow-band hot electron photodetector based on an embedded Au–Si nanotrench metasurface. The device achieves strong narrowband anisotropic absorption of 85% with a full width at half-maximum of 30 nm. The photodetector exhibits a self-powered and tunable narrow-band photoresponse across the near-infrared regime, achieving a responsivity of 1.7 mA/W at λ = 1450 nm, representing a 2.83-fold enhancement over conventional plasmonic gratings. Moreover, the polarization ratio of 29 is among the highest reported and can be further improved to 130 using a subwavelength critically embedded configuration, demonstrating outstanding polarization imaging and sensing capability. These results pave the way for implementing compact, tunable, narrowband, polarization-sensitive all-silicon near-infrared photodetectors for applications in photocatalysis, polarized imaging, communication, and biosensing.