High-Responsivity Mid-Infrared Graphene Detectors with Antenna-Enhanced Photocarrier Generation and Collection
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Author(s)
Yao, Yu
Shankar, Raji
Rauter, Patrick
Song, Yi
Kong, Jing
Loncar, Marko
Capasso, Federico
Date Issued
June 2014
Journal
Nano Letters
Publisher
American Chemical Society (ACS)
Citation
Yao, Yu et al. “High-Responsivity Mid-Infrared Graphene Detectors with Antenna-Enhanced Photocarrier Generation and Collection.” Nano Letters 14, 7 (July 2014): 3749–3754 © 2014 American Chemical Society
Version
Author's final manuscript
Abstract
Graphene is an attractive photoconductive material for optical detection due to its broad absorption spectrum and ultrashort response time. However, it remains a great challenge to achieve high responsivity in graphene detectors because of graphene’s weak optical absorption (only 2.3% in the monolayer graphene sheet) and short photocarrier lifetime (<1 ps). Here we show that metallic antenna structures can be designed to simultaneously improve both light absorption and photocarrier collection in graphene detectors. The coupled antennas concentrate free space light into the nanoscale deep-subwavelength antenna gaps, where the graphene light interaction is greatly enhanced as a result of the ultrahigh electric field intensity inside the gap. Meanwhile, the metallic antennas are designed to serve as electrodes that collect the generated photocarriers very efficiently. We also elucidate the mechanism of photoconductive gain in the graphene detectors and demonstrate mid-infrared (mid-IR) antenna-assisted graphene detectors at room temperature with more than 200 times enhancement of responsivity (∼0.4 V/W at λ0 = 4.45 μm) compared to devices without antennas (<2 mV/W).
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
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DOI of Published Version
https://doi.org/10.1021/nl500602n
