
Nanobowls-assisted broadband absorber for unbiased Si-based infrared photodetection
Author(s) -
Leyuan Zhou,
Cheng Zhang,
Liujing Li,
Tingting Liu,
Ké Li,
Shaolong Wu,
Xiaofeng Li
Publication year - 2021
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.423897
Subject(s) - photodetection , materials science , optoelectronics , responsivity , photodetector , optics , specific detectivity , schottky barrier , plasmon , surface plasmon , physics , diode
Hot electrons from the nonradiative decay of surface plasmons have drawn extensive attention due to the outstanding performance in realizing below-bandgap photodetection. However, the widely employed metallic nanostructures are normally complex and delicate with a great challenge in large-area fabrication, and there is a great limitation to achieve substantial photoresponse at relatively long wavelengths (e.g., 2000nm) with polarization- and incident-angle independence. In this study, we theoretically and experimentally demonstrate a broadband, omnidirectional, and polarization-insensitive absorber based on wafer-scale silicon honeycomb nanobowls with 20-nm-thick gold overlayer. The average absorption across the long wave near infrared band (LW-NIR, i.e., 1100-2500 nm) is higher than 82%, which is contributed from the random nature and multimode localized plasmonic resonances excited on the side walls of nanobowls. Benefitted from the well-connected thin Au film and relatively low Schottky barrier, the generated hot electrons have a high transport probability to reach Schottky interface and participate in the interfacial charge transfer process. As a result, the hot-electron photodetector under no bias realizes a broadband photodetection up to 2000nm wavelength with a responsivity of 0.145 mA/W, and its cutoff wavelength is predicted up to 3300 nm by fitting the experimental result with Fowler theory. Our proposed Au/Si nanobowls photodetector could open a pathway to further extend the detection wavelength of Si-based photodetectors with a large-area and low-cost fabrication process, which promotes practical hot-electron applications.