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

Authors:

Liu, Xiaoge ^[1]; Kang, Ju -Hyung ^[1]; Yuan, Hongtao ^[2]; Park, Junghyun ^[1]; Kim, Soo Jin ^[1]; Cui, Yi ^[3]; Hwang, Harold Y. ^[3]; Brongersma, Mark L. ^[1]

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+ Show Author Affiliations

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:

Mon Jun 12 00:00:00 EDT 2017

Research Org.:

SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1394086

Grant/Contract Number:  

AC02-76SF00515

Resource Type:

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