Gold-Patched Graphene Nanoribbons for High-Responsivity and Ultrafast Photodetection from Visible to Infrared Regimes

TL;DR

This paper introduces gold-patched graphene nanoribbons that enable broadband, ultrafast, and highly responsive photodetection from visible to infrared wavelengths, surpassing previous limitations of graphene photodetectors.

Contribution

The authors develop a novel nanostructure combining graphene nanoribbons with gold patches, achieving high responsivity and ultrafast operation without quantum dots or tunneling barriers.

Findings

Responsivity of 0.6 A/W at 0.8 μm and 11.5 A/W at 20 μm

Operation speeds exceeding 50 GHz

Response times improved by over seven orders of magnitude

Abstract

Graphene is a very attractive material for broadband photodetection in hyperspectral imaging and sensing systems. However, its potential use has been hindered by tradeoffs between the responsivity, bandwidth, and operation speed of existing graphene photodetectors. Here, we present engineered photoconductive nanostructures based on gold-patched graphene nanoribbons, which enable simultaneous broadband and ultrafast photodetection with high responsivity. These nanostructures merge the advantages of broadband optical absorption, ultrafast photocarrier transport, and carrier multiplication in graphene nanoribbons with the ultrafast transport of photocarriers to the gold patches before recombination. Through this approach, high-responsivity operation is achieved without the use of bandwidth- and speed-limiting quantum dots, defect states, or tunneling barriers. We demonstrate high-responsivity photodetection from the visible to the infrared regime (0.6 A/W at 0.8 {\mu}m and 11.5 A/W at 20 {\mu}m) with operation speeds exceeding 50 GHz. Our results demonstrate an improvement of the response times by more than seven orders of magnitude and an increase in bandwidths of one order of magnitude compared to those of higher-responsivity graphene photodetectors based on quantum dots and tunneling barriers.