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Proceedings Paper

Terahertz imaging and time-domain spectroscopy of large-area graphene on silicon
Author(s): J. L. Tomaino; A. D. Jameson; J. Kevek; M. J. Paul; A. M. van der Zande; R. A. Barton; P. L. McEuen; E. D. Minot; Yun-Shik Lee
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Paper Abstract

We demonstrate THz imaging and time-domain spectroscopy of a single-layer graphene film. The large-area graphene was grown by chemical vapor deposition on Cu-foil and subsequently transferred to a Si substrate. We took a transmission image of the graphene/Si sample measured by a Si:bolometer (pixel size is 0.4-mm). The graphene film (transmission: 36 - 41%) is clearly resolved against the background of the Si substrate (average transmission: 56.6%). The strong THz absorption by the graphene layer indicates that THz carrier dynamics are dominated by intraband transitions. A theoretical analysis based on the Fresnel coefficients for a metallic thin film shows that the local sheet resistance varies across the sample from 420 to 590 Ohm, consistent with electron mobility ~ 3,000 cm2V-1s-1. We also measured time-resolved THz waveforms through the Si substrate and the graphene/Si sample. The waveforms consist of a series of single-cycle THz pulses: a directly transmitted pulse, then subsequent "echos" corresponding to multiple reflections from the substrate. The amplitude difference between graphene/Si pulses and Si pulses becomes more pronounced as the pulses undergo more reflections. From these measurements, we obtained spectrally flat transmission spectra of the transmitted pulses and the average sheet resistance 480 Ohm, consistent with the results of the power transmission measurement. The flat spectral responses indicate that the carrier scattering time in our graphene sample is much shorter than the THz pulse duration.

Paper Details

Date Published: 20 February 2012
PDF: 8 pages
Proc. SPIE 8260, Ultrafast Phenomena and Nanophotonics XVI, 82600Z (20 February 2012); doi: 10.1117/12.905525
Show Author Affiliations
J. L. Tomaino, Oregon State Univ. (United States)
A. D. Jameson, Oregon State Univ. (United States)
J. Kevek, Oregon State Univ. (United States)
M. J. Paul, Oregon State Univ. (United States)
A. M. van der Zande, Cornell Univ. (United States)
R. A. Barton, Cornell Univ. (United States)
P. L. McEuen, Cornell Univ. (United States)
E. D. Minot, Oregon State Univ. (United States)
Yun-Shik Lee, Oregon State Univ. (United States)

Published in SPIE Proceedings Vol. 8260:
Ultrafast Phenomena and Nanophotonics XVI
Markus Betz; Abdulhakem Y. Elezzabi; Jin-Joo Song; Kong-Thon Tsen, Editor(s)

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