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Title: Electrical tuning of a quantum plasmonic resonance

Abstract

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 λ 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. As a result,more » a quantum-mechanical model including the quantum size effect reproduces the experimental results, whereas a classical model only predicts a red shift.« less

Authors:
 [1];  [1];  [2];  [1];  [1];  [3];  [3];  [1]
  1. Stanford Univ., Stanford, CA (United States)
  2. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Nanjing Univ., Nanjing (China)
  3. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1394086
Grant/Contract Number:
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Nanotechnology
Additional Journal Information:
Journal Volume: 12; Journal Issue: 9; Journal ID: ISSN 1748-3387
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Liu, Xiaoge, Kang, Ju -Hyung, Yuan, Hongtao, Park, Junghyun, Kim, Soo Jin, Cui, Yi, Hwang, Harold Y., and Brongersma, Mark L. Electrical tuning of a quantum plasmonic resonance. United States: N. p., 2017. Web. doi:10.1038/NNANO.2017.103.
Liu, Xiaoge, Kang, Ju -Hyung, Yuan, Hongtao, Park, Junghyun, Kim, Soo Jin, Cui, Yi, Hwang, Harold Y., & Brongersma, Mark L. Electrical tuning of a quantum plasmonic resonance. United States. doi:10.1038/NNANO.2017.103.
Liu, Xiaoge, Kang, Ju -Hyung, Yuan, Hongtao, Park, Junghyun, Kim, Soo Jin, Cui, Yi, Hwang, Harold Y., and Brongersma, Mark L. 2017. "Electrical tuning of a quantum plasmonic resonance". United States. doi:10.1038/NNANO.2017.103.
@article{osti_1394086,
title = {Electrical tuning of a quantum plasmonic resonance},
author = {Liu, Xiaoge and Kang, Ju -Hyung and Yuan, Hongtao and Park, Junghyun and Kim, Soo Jin and Cui, Yi and Hwang, Harold Y. and Brongersma, Mark L.},
abstractNote = {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 λF 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. As a result, a quantum-mechanical model including the quantum size effect reproduces the experimental results, whereas a classical model only predicts a red shift.},
doi = {10.1038/NNANO.2017.103},
journal = {Nature Nanotechnology},
number = 9,
volume = 12,
place = {United States},
year = 2017,
month = 6
}

Journal Article:
Free Publicly Available Full Text
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  • We report an experimental demonstration of electrical tuning of plasmon resonances of optical nanopatch antennas over a wide wavelength range. The antennas consist of silver nanocubes separated from a gold film by a thin 8 nm polyelectrolyte spacer layer. By using ionic liquid and indium tin oxide coated glass as a top electrode, we demonstrate dynamic and reversible tuning of the plasmon resonance over 100 nm in the visible wavelength range using low applied voltages between −3.0 V and 2.8 V. The electrical potential is applied across the nanoscale gap causing changes in the gap thickness and dielectric environment which, in turn, modifies themore » plasmon resonance. The observed tuning range is greater than the full-width-at-half-maximum of the plasmon resonance, resulting in a tuning figure of merit of 1.05 and a tuning contrast greater than 50%. Our results provide an avenue to create active and reconfigurable integrated nanophotonic components for applications in optoelectronics and sensing.« less
  • We investigate the optical response of a gold nanorod (NR) array coupled with a gold nanoparticle (NP) film. We show that, as the NP density is increased to the percolating regime, the NR-NP hybrids are tuned into plasmonic Fano resonance, characterized by the coherent coupling of the discrete plasmonic modes of the NR array with the continuous plasmonic modes of the NP film. As a consequence, the optical transmission of the NP film is substantially enhanced. Even more strikingly, the electromagnetic fields around the NR array become much stronger, as reflected by the two orders of magnitude enhancement in themore » avalanche photoluminescence. These findings may prove instrumental in the design of various plasmonic nanodevices.« less
  • We investigate the optical response of a gold nanorod array coupled with a semicontinuous nanoparticle film. We find that, as the gold nanoparticle film is adjusted to the percolating regime, the nanorod-film hybrids are tuned into plasmonic Fano resonance, characterized by the coherent coupling of discrete plasmonic modes of the nanorod array with the continuum band of the percolating film. Consequently, optical transmission of the percolating film is substantially enhanced. Even more strikingly, electromagnetic fields around the nanorod array become much stronger, as reflected by 2 orders of magnitude enhancement in the avalanche multiphoton luminescence. These findings may prove instrumentalmore » in the design of various plasmonic nanodevices.« less
  • The Drude equation for dielectric constant ϵ(E) depends on four parameters: ϵ∞, effective mass m*, optical mobility µopt, and optical carrier concentration nopt. By solving this equation at ϵ(Eres)=0, we obtain a relationship between µopt and nopt at constant plasmonic resonance energy Eres [or wavelength λres (µm)=1.2395/Eres (eV)]. A family of µopt versus nopt curves covering a range of λres values (including the limiting wavelength λres=∞) constitutes a plasmonic resonance phase diagram (PRPD) for a semiconductor defined by only ϵ∞ and m*. The PRPD is a convenient instrument that allows an immediate prediction of λres from Hall-effect measurements of µHmore » and nH. We apply the PRPD analysis to a series of ten ZnO samples grown by pulsed laser deposition at 200°C in an ambient of 33%H2:67%Ar and annealed in 25°C steps for 10 min in air at various temperatures from 400 to 600°C. For the samples annealed at 550°C or lower, the µH/nH points yield predicted values of λres that range from 1.07 to 2.80 µm; however, the 575 and 600°C samples are predicted to have no resonance at all. Reflectance curves for the eight samples annealed up to 550 °C decrease slowly from 6 eV down to about Eres= 0.5–1.15 eV, and then increase rapidly for E < Eres. In contrast, there is no such resonance-related increase for the 575 and 600 °C samples. Satisfactory agreement is found between the reflectance minima and the Hall-effect-predicted values of λres.« less