Enabling highly efficient infrared silicon photodetectors via disordered metasurfaces with upconversion nanoparticles.

Silicon photodetectors are highly desirable for their CMOS compatibility, low cost, and fast response speed. However, their applications in the infrared (IR) regime are inherently limited by the intrinsic bandgap of silicon, which limits the detection wavelengths to being below 1.1 μm. Although several methods have been developed to extend silicon photodetectors further in the IR range, these approaches often introduce additional challenges. Here, we present an approach to overcome these limitations by integrating disordered metasurfaces with upconversion nanoparticles, enabling IR detection by silicon photodetectors. The disordered design consisting of hybrid Mie-plasmonic cavities can enhance both the near-field localization and wide-band light absorption. The measured responsivity of the disordered element for 1550-nm laser is 0.22 A/W at room temperature, corresponding to an external quantum efficiency of 17.6%. Our design not only enhances the photocurrent performance, but also extends the working wavelength of silicon photodetectors to IR spectrum applications.