Polarization-Independent Indium Phosphide Nanowire Photodetectors

Although semiconductor nanowire (NW) photodetectors are promising building blocks for nanoscale on-chip optoelectronic integration applications, poor absorption, and strong light polarization dependence due to their inherent anisotropic geometry remain an issue. Here, a polarization-insensitive photodetector is designed and experimentally demonstrated, which consists of an InP NW embedded in a dual-split bull's eye (DSBE) plasmonic antenna. The resultant photodetector exhibits a low noise equivalent power of 0.97 pW and a photoresponsivity of 0.96 A W^-1 at 740 nm with an external quantum efficiency of 163%. Importantly, the device exhibits an ultralow polarization dependence characteristic with a polarization degree significantly reduced from 91% down to 6%. The improved performance stems from the intrinsic symmetry of the orthogonal DSBE and the strong surface plasmon coupling, which significantly boosts the optical concentration abilities at all polarization angles as compared to the bare NW photodetector. This NW photodetector-antenna design provides a pathway for the development of high-performance nanoscale photodetectors for applications in advanced sensing, imaging, and quantum communications.