Boosting Hot-Electron Extraction Through Deep Groove Perfect Absorber for Si-Based Photodetector

We propose a deep-groove thin-film active antenna for Si-based hot-electron photodetectors. Simulation results show that near-perfect absorption is achieved when the incidence light is strongly confined within the grooves at cavity resonance modes. Meanwhile, superior internal quantum efficiency is expected due to that the generated hot electrons can be effectively extracted by emitting over the designed multi Schottky barriers, especially at the bottom region of the grooves. By using a rigorous calculation method based on the specific absorption spatial distribution, it is found that higher photoresponsivity can be obtained by tailoring the groove depth and metal thickness to make sure more hot electrons are generated at the bottom region of the grooves. The optimized device exhibits an unbiased responsivity of ~12 mA/W at 1550 nm, which suggests a promising candidate for infrared Si-based photodetection.