Wafer-Scale Fabrication of Graphene-Based Plasmonic Photodetector with Polarization-Sensitive, Broadband, and Enhanced Response

Graphene-based photodetectors draw tremendous interests for broadband photodetection in optical communications, sensing, and hyperspectral imaging. However, the extremely low light absorption coefficient of graphene posts a great challenge for high-efficiency photodetection. Although plasmonic nanostructures provide resonant absorption enhancement and impressive responsivity, the current fabrication techniques suffer from being time-consuming, low-yield, and potentially high-cost. In this work, a wafer-scale graphene-Au nanogratings (Gra-Au NGs) plasmonic photodetector array is fabricated via two-beam holographic lithography, which achieves a photosensitive area of 1 mm(2), showing balanced abilities of polarization-sensitive, broadband, and enhanced photoresponse from visible to near-infrared regions. The maximum polarization extinction ratio and responsivity of the Gra-Au NGs photodetector reach 6.65 and 2.95 mA W-1. The surface plasmon resonance of Au NGs and near-field coupling with graphene render strong electric field confinement and enhanced light absorption, which improve the device photoresponse and polarization sensitivity. The hot electrons generation and transportation models in the Gra-Au NGs heterojunction are proposed, perfectly matching with the photocurrent mapping and equalized energy band distribution. This work enlightens the wafer-scale fabrication of graphene-based plasmonic photodetectors, and it can trigger the advances of free-space detection, such as remote sensing and satellite communication.