Plasmonic‐Based Negative Photoconductance Photodetectors for a New Optical Window

In recent years, the short‐wave infrared (SWIR) region has been extended to 2 µm, opening new opportunities for optical windows and light detection and ranging (LiDAR) applications, particularly due to advantages such as eye safety and long‐range detection. In this study, we present the development and demonstration of a negative photoconductance (NPC)‐based detector operating at a wavelength of 2 µm. Illumination excites hot electrons via the anisotropic surface plasmon resonance in metal films, while the grating structure introduces strong polarization dependence and promotes multiple collisions between hot and conduction electrons. At a bias voltage of 70 mV, the device exhibited a responsivity of 979 mA/W and a detectivity of 2.59 × 10 11 Jones. The device demonstrated response and recovery times on the order of milliseconds, governed by the plasmonic effect. Furthermore, the device operated efficiently across a wide temperature range from 123 to 473 K. These results highlight the device's capability to operate over a broad temperature range while maintaining high responsivity, high detectivity, and fast switching, thereby paving the way for practical new optical wavelength photodetectors around 2 µm.