Semimetal‐Controlled Silicon‐Based Ultra‐Broadband Photodetector for Single‐Pixel Imaging and High‐Sensitivity Infrared Gas Sensing

Abstract Multifunctional photodetectors require the photosensitive layer to exhibit both broad spectral response and high‐performance characteristics. Silicon‐based photodetectors are widely applied, benefiting from high quantum efficiency and mature fabrication processes. However, the silicon bandgap of over 1 eV limits its operational range across a broad spectrum. In this study, a semimetal‐controlled, silicon‐based broadband photodetector is developed, in which the semimetal ZrTe 3 functions as both the barrier control layer and the light absorption layer. The results demonstrate that the designed silicon photodetector achieves an ultra‐broad spectral response ranging from ultraviolet to mid‐infrared (355 nm to 3.35 µm). With its high responsivity and ultrafast response time, a single‐pixel imaging module and a low‐concentration gas sensing module are further developed. The imaging module can capture clear contours at a sampling rate as low as 1%, highlighting its significant potential in computational optics. The gas sensing module detects CH 4 with a lower detection limit of 5.35 ppm in the near‐infrared and successfully demonstrates stable gas detection capabilities in the prototype.