Photocurrent enhancement of graphene photodetectors by photon tunneling of light into surface plasmons

Maleki, A, Cumming, B, Gu, M, Downes, J, Coutts, D and Dawes, J 2017, 'Photocurrent enhancement of graphene photodetectors by photon tunneling of light into surface plasmons', Journal of Optics (United Kingdom), vol. 19, no. 10, pp. 1-8.


Document type: Journal Article
Collection: Journal Articles

Title Photocurrent enhancement of graphene photodetectors by photon tunneling of light into surface plasmons
Author(s) Maleki, A
Cumming, B
Gu, M
Downes, J
Coutts, D
Dawes, J
Year 2017
Journal name Journal of Optics (United Kingdom)
Volume number 19
Issue number 10
Start page 1
End page 8
Total pages 8
Publisher Institute of Physics Publishing
Abstract We demonstrate that surface plasmon resonances excited by photon tunneling through an adjacent dielectric medium enhance the photocurrent detected by a graphene photodetector. The device is created by overlaying a graphene sheet over an etched gap in a gold film deposited on glass. The detected photocurrents are compared for five different excitation wavelengths, ranging from λ0 = 570 nm to λ0 = 730 nm. Although the device is not optimized, the photocurrent excited with incident p-polarized light (which excites resonant surface plasmons) is significantly amplified in comparison with that for s-polarized light (without surface plasmon resonances). We observe that the photocurrent is greater for shorter wavelengths (for both s- and p-polarizations) with increased photothermal current. Position-dependent Raman spectroscopic analysis of the optically-excited graphene photodetector indicates the presence of charge carriers in the graphene near the metallic edge. In addition, we show that the polarity of the photocurrent reverses across the gap as the incident light spot moves across the gap. Graphene-based photodetectors offer a simple architecture which can be fabricated on dielectric waveguides to exploit the plasmonic photocurrent enhancement of the evanescent field. Applications for these devices include photodetection, optical sensing and direct plasmonic detection.
Subject Optical Physics not elsewhere classified
Keyword(s) grapheme
photodetectors
surface plasmons
DOI - identifier 10.1088/2040-8986/aa86d3
Copyright notice © 2017 IOP Publishing
ISSN 2040-8978
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