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Volume 178, 2015
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High-density metallic nanogap arrays for the sensitive detection of single-walled carbon nanotube thin films

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Abstract

We have investigated the extraordinary optical transmission of terahertz waves through an array of nanogaps with varying dimensions and periodicities, and used this platform to demonstrate terahertz sensing of a thin film of single-walled carbon nanotubes. We have used atomic layer lithography to fabricate periodic arrays of nanogap loops that have a gap size of 2 nm and a loop length of 100 μm (aspect ratio of 50 000). These sub-mm-scale loops of nanogaps can sustain terahertz electromagnetic resonances along the contour. We have characterized the transmission of terahertz waves through the nanogap arrays and investigated the influence of inter-gap electromagnetic coupling as the array periodicity shrinks from 100 μm to 4 μm. While the gaps occupy only 0.1% of the surface area, we have measured an amplitude (|E|) transmittance of over 50% due to the strong and broadband field enhancement inside the nanogaps. The absolute transmission through the 2 nm gaps along the rectangular loops can be boosted up to 25%, while it is only 1% for annular gaps with the same perimeter. Furthermore, the extremely tight field confinement and strong field enhancement near the 2 nm gap lead to 43% extinction of THz waves in a 10 nm-thick film of single-walled carbon nanotubes over the gaps. On the other hand, THz extinction by the same nanotube film on a bare glass substrate is only 2%. These nanogaps pave the way toward developing sensitive terahertz detectors for biological and chemical targets.

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Publication details

The article was received on 24 Nov 2014, accepted on 05 Dec 2014 and first published on 11 Mar 2015


Article type: Paper
DOI: 10.1039/C4FD00233D
Faraday Discuss., 2015,178, 195-201

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    High-density metallic nanogap arrays for the sensitive detection of single-walled carbon nanotube thin films

    H. Park, S. Namgung, X. Chen and S. Oh, Faraday Discuss., 2015, 178, 195
    DOI: 10.1039/C4FD00233D

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