TY - JOUR
T1 - Electrical tuning of a quantum plasmonic resonance
AU - Liu, Xiaoge
AU - Kang, Ju Hyung
AU - Yuan, Hongtao
AU - Park, Junghyun
AU - Kim, Soo Jin
AU - Cui, Yi
AU - Hwang, Harold Y.
AU - Brongersma, Mark L.
N1 - Funding Information:
This work was supported by the Extreme Electron Concentration Devices (EXEDE) MURI program of the Office of Naval Research (ONR) through grant no. N00014-12-1-0976. H.T.Y. and Y.C. acknowledge support by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under contract DE-AC02-76SF00515.
Publisher Copyright:
© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
PY - 2017/9/1
Y1 - 2017/9/1
N2 - Surface plasmon (SP) excitations in metals facilitate confinement of light into deep-subwavelength volumes and can induce strong light-matter interaction. Generally, the SP resonances supported by noble metal nanostructures are explained well by classical models, at least until the nanostructure size is decreased to a few nanometres, approaching the Fermi wavelength F of the electrons. Although there is a long history of reports on quantum size effects in the plasmonic response of nanometre-sized metal particles, systematic experimental studies have been hindered by inhomogeneous broadening in ensemble measurements, as well as imperfect control over size, shape, faceting, surface reconstructions, contamination, charging effects and surface roughness in single-particle measurements. In particular, observation of the quantum size effect in metallic films and its tuning with thickness has been challenging as they only confine carriers in one direction. Here, we show active tuning of quantum size effects in SP resonances supported by a 20-nm-thick metallic film of indium tin oxide (ITO), a plasmonic material serving as a low-carrier-density Drude metal. An ionic liquid (IL) is used to electrically gate and partially deplete the ITO layer. The experiment shows a controllable and reversible blue-shift in the SP resonance above a critical voltage. A quantum-mechanical model including the quantum size effect reproduces the experimental results, whereas a classical model only predicts a red shift.
AB - Surface plasmon (SP) excitations in metals facilitate confinement of light into deep-subwavelength volumes and can induce strong light-matter interaction. Generally, the SP resonances supported by noble metal nanostructures are explained well by classical models, at least until the nanostructure size is decreased to a few nanometres, approaching the Fermi wavelength F of the electrons. Although there is a long history of reports on quantum size effects in the plasmonic response of nanometre-sized metal particles, systematic experimental studies have been hindered by inhomogeneous broadening in ensemble measurements, as well as imperfect control over size, shape, faceting, surface reconstructions, contamination, charging effects and surface roughness in single-particle measurements. In particular, observation of the quantum size effect in metallic films and its tuning with thickness has been challenging as they only confine carriers in one direction. Here, we show active tuning of quantum size effects in SP resonances supported by a 20-nm-thick metallic film of indium tin oxide (ITO), a plasmonic material serving as a low-carrier-density Drude metal. An ionic liquid (IL) is used to electrically gate and partially deplete the ITO layer. The experiment shows a controllable and reversible blue-shift in the SP resonance above a critical voltage. A quantum-mechanical model including the quantum size effect reproduces the experimental results, whereas a classical model only predicts a red shift.
UR - http://www.scopus.com/inward/record.url?scp=85029072623&partnerID=8YFLogxK
U2 - 10.1038/nnano.2017.103
DO - 10.1038/nnano.2017.103
M3 - Article
C2 - 28604706
AN - SCOPUS:85029072623
SN - 1748-3387
VL - 12
SP - 866
EP - 870
JO - Nature Nanotechnology
JF - Nature Nanotechnology
IS - 9
ER -