Long Xiao

Ongoing efforts have been made to improve the photoresponsivity of plasmonic photodetectors. In this work, the photodetectors based on transparent conductive oxide (TCO)/Semiconductor/Metal configuration especially with a roughened interface were investigated numerically, and the effect of the roughness on the injection efficiency of hot electrons was analyzed. The simulated results indicate that a roughened structure alleviates effectively the momentum mismatch of hot electrons at the metal/semiconductor interface due to asymmetry factor, and greatly improves the injection efficiency as well as photoresponsivity. At the incidence wavelength of 1550 nm, the photoresponsivity increased by about 8 times. Meanwhile, the influence on the resonant wavelength shift is negligible where the roughness is nano-scale. Our work provides a valuable guidance for the theoretical and experimental research of plasmonic photodetectors.

This paper presents a waveguide-fed one-dimensional bull-eye antenna, which innovatively combines a waveguide slot array antenna with a bull-eye antenna. The antenna array uses a simple bulleye structure and the feeding uses the waveguide slot antenna with a large power capacity. The simulation results show that the antenna has a high gain of 23dBi and a power capacity of 9MW at 1.9GHz. The antenna gain increases with the increase of the number of grooves of the bulleye antenna or the number of slots in the waveguide. The antenna has the features of high gain, low loss, high power capacity, low cost and easy conformation.

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.