Mapping the electromagnetic field confinement in the gap of germanium nanoantennas with plasma wavelength of 4.5 micrometers

Journal article (2016)

Authors

Eugenio Calandrini Istituto Italiano di Tecnologia
Tommaso Venanzi Sapienza University of Rome
Michele Ortolani Sapienza University of Rome
Felice Appugliese Sapienza University of Rome
Michela Badioli Sapienza University of Rome
Valeria Giliberti Sapienza University of Rome, Istituto Italiano di Tecnologia
Leonetta Baldassarre Sapienza University of Rome, Istituto Italiano di Tecnologia
Paolo Biagioni Politecnico di Milano
Francesco De Angelis Istituto Italiano di Tecnologia
Wolfgang M. Klesse University of New South Wales
G. Scappucci QCD/Scappucci Lab - QuTech Advanced Research Centre , University of New South Wales
Research Group
QCD/Scappucci Lab (QuTech Advanced Research Centre) (TU Delft)
Copyright: © 2016 Eugenio Calandrini, Tommaso Venanzi, Felice Appugliese, Michela Badioli, Valeria Giliberti, Leonetta Baldassarre, Paolo Biagioni, Francesco De Angelis, Wolfgang M. Klesse, G. Scappucci, Michele Ortolani
DOI: https://doi.org/10.1063/1.4962976
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Published Date

19-09-2016

Language

English

Reuse Rights

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Faculty

QuTech Advanced Research Centre

Department

Quantum Computing Division

Research Group

QCD/Scappucci Lab

Abstract

We study plasmonic nanoantennas for molecular sensing in the mid-infrared made of heavily doped germanium, epitaxially grown with a bottom-up doping process and featuring free carrier density in excess of 1020 cm-3. The dielectric function of the 250 nm thick germanium film is determined, and bow-tie antennas are designed, fabricated, and embedded in a polymer. By using a near-field photoexpansion mapping technique at λ = 5.8 μm, we demonstrate the existence in the antenna gap of an electromagnetic energy density hotspot of diameter below 100 nm and confinement volume 105 times smaller than λ3.

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