High-Responsivity Mid-Infrared Graphene Detectors with Antenna-Enhanced Photocarrier Generation and Collection
Author(s)
Yao, Yu; Shankar, Raji; Rauter, Patrick; Song, Yi; Kong, Jing; Loncar, Marko; Capasso, Federico; ... Show more Show less
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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).
Date issued
2014-06Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer ScienceJournal
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
ISSN
1530-6984
1530-6992