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Open AccessArticle

Nanoantenna Structure with Mid-Infrared Plasmonic Niobium-Doped Titanium Oxide

International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044, Japan
Department of Condensed Matter Physics, Graduate school of Science, Hokkaido University, Kita-10 Nishi-8 Kita-ku, Sapporo 060-0810, Japan
Institute of Photonics Technology, Jinan University, Guangzhou 510632, China
Nanotechnology Innovation Station, National Institute for Materials Science, Tsukuba 305-0044, Japan
Author to whom correspondence should be addressed.
Micromachines 2020, 11(1), 23;
Received: 17 November 2019 / Revised: 20 December 2019 / Accepted: 23 December 2019 / Published: 24 December 2019
(This article belongs to the Special Issue Infrared Nanophotonics: Materials, Devices, and Applications)
Among conductive oxide materials, niobium doped titanium dioxide has recently emerged as a stimulating and promising contestant for numerous applications. With carrier concentration tunability, high thermal stability, mechanical and environmental robustness, this is a material-of-choice for infrared plasmonics, which can substitute indium tin oxide (ITO). In this report, to illustrate great advantages of this material, we describe successful fabrication and characterization of niobium doped titanium oxide nanoantenna arrays aiming at surface-enhanced infrared absorption spectroscopy. The niobium doped titanium oxide film was deposited with co-sputtering method. Then the nanopatterned arrays were prepared by electron beam lithography combined with plasma etching and oxygen plasma ashing processes. The relative transmittance of the nanostrip and nanodisk antenna arrays was evaluated with Fourier transform infrared spectroscopy. Polarization dependence of surface plasmon resonances on incident light was examined confirming good agreements with calculations. Simulated spectra also present red-shift as length, width or diameter of the nanostructures increase, as predicted by classical antenna theory. View Full-Text
Keywords: nanoantenna; niobium-doped titanium oxide; mid-infrared plasmonics nanoantenna; niobium-doped titanium oxide; mid-infrared plasmonics
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Ngo, H.D.; Chen, K.; Handegård, Ø.S.; Doan, A.T.; Ngo, T.D.; Dao, T.D.; Ikeda, N.; Ohi, A.; Nabatame, T.; Nagao, T. Nanoantenna Structure with Mid-Infrared Plasmonic Niobium-Doped Titanium Oxide. Micromachines 2020, 11, 23.

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