Split-Wedge Antennas with Sub-5 nm Gaps for Plasmonic Nanofocusing

Xiaoshu Chen; Nathan C. Lindquist; Daniel J. Klemme; Prashant Nagpal; David J. Norris; Sang Hyun Oh

doi:10.1021/acs.nanolett.6b04113

Split-Wedge Antennas with Sub-5 nm Gaps for Plasmonic Nanofocusing

Xiaoshu Chen, Nathan C. Lindquist, Daniel J. Klemme, Prashant Nagpal, David J. Norris, Sang Hyun Oh

Electrical and Computer Engineering

Research output: Contribution to journal › Article › peer-review

52 Scopus citations

Abstract

We present a novel plasmonic antenna structure, a split-wedge antenna, created by splitting an ultrasharp metallic wedge with a nanogap perpendicular to its apex. The nanogap can tightly confine gap plasmons and boost the local optical field intensity in and around these opposing metallic wedge tips. This three-dimensional split-wedge antenna integrates the key features of nanogaps and sharp tips, i.e., tight field confinement and three-dimensional nanofocusing, respectively, into a single platform. We fabricate split-wedge antennas with gaps that are as small as 1 nm in width at the wafer scale by combining silicon V-grooves with template stripping and atomic layer lithography. Computer simulations show that the field enhancement and confinement are stronger at the tip-gap interface compared to what standalone tips or nanogaps produce, with electric field amplitude enhancement factors exceeding 50 when near-infrared light is focused on the tip-gap geometry. The resulting nanometric hotspot volume is on the order of λ³/10⁶. Experimentally, Raman enhancement factors exceeding 10⁷ are observed from a 2 nm gap split-wedge antenna, demonstrating its potential for sensing and spectroscopy applications.

Original language	English (US)
Pages (from-to)	7849-7856
Number of pages	8
Journal	Nano letters
Volume	16
Issue number	12
DOIs	https://doi.org/10.1021/acs.nanolett.6b04113
State	Published - Dec 14 2016

Bibliographical note

Funding Information:
This research was supported by the Office of Naval Research Young Investigator Program (to X.S.C., N.C.L. and S.-H.O.), the National Science Foundation (CMMI No. 1363334 for D.J.K. and S.-H.O.; ECCS No. 1610333 for S.-H.O.; CAREER Award No. 1552642 for N.C.L.; NSF Graduate Research Fellowship for D.J.K.), Seagate Technology (MINT grant for S.-H.O.), and the MnDrive Initiative from the State of Minnesota (to D.J.K. and S.-H.O.). X.S.C. acknowledges support from the 3M Science and Technology Fellowship and the University of Minnesota Doctoral Dissertation Fellowship.

Publisher Copyright:
© 2016 American Chemical Society.

Keywords

Optical antenna
atomic layer deposition
atomic layer lithography
gap plasmon
surface-enhanced Raman scattering (SERS)
template stripping

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10.1021/acs.nanolett.6b04113

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@article{a4ca952b268e4ff7803b75b9bb44e8f5,

title = "Split-Wedge Antennas with Sub-5 nm Gaps for Plasmonic Nanofocusing",

abstract = "We present a novel plasmonic antenna structure, a split-wedge antenna, created by splitting an ultrasharp metallic wedge with a nanogap perpendicular to its apex. The nanogap can tightly confine gap plasmons and boost the local optical field intensity in and around these opposing metallic wedge tips. This three-dimensional split-wedge antenna integrates the key features of nanogaps and sharp tips, i.e., tight field confinement and three-dimensional nanofocusing, respectively, into a single platform. We fabricate split-wedge antennas with gaps that are as small as 1 nm in width at the wafer scale by combining silicon V-grooves with template stripping and atomic layer lithography. Computer simulations show that the field enhancement and confinement are stronger at the tip-gap interface compared to what standalone tips or nanogaps produce, with electric field amplitude enhancement factors exceeding 50 when near-infrared light is focused on the tip-gap geometry. The resulting nanometric hotspot volume is on the order of λ3/106. Experimentally, Raman enhancement factors exceeding 107 are observed from a 2 nm gap split-wedge antenna, demonstrating its potential for sensing and spectroscopy applications.",

keywords = "Optical antenna, atomic layer deposition, atomic layer lithography, gap plasmon, surface-enhanced Raman scattering (SERS), template stripping",

author = "Xiaoshu Chen and Lindquist, {Nathan C.} and Klemme, {Daniel J.} and Prashant Nagpal and Norris, {David J.} and Oh, {Sang Hyun}",

note = "Funding Information: This research was supported by the Office of Naval Research Young Investigator Program (to X.S.C., N.C.L. and S.-H.O.), the National Science Foundation (CMMI No. 1363334 for D.J.K. and S.-H.O.; ECCS No. 1610333 for S.-H.O.; CAREER Award No. 1552642 for N.C.L.; NSF Graduate Research Fellowship for D.J.K.), Seagate Technology (MINT grant for S.-H.O.), and the MnDrive Initiative from the State of Minnesota (to D.J.K. and S.-H.O.). X.S.C. acknowledges support from the 3M Science and Technology Fellowship and the University of Minnesota Doctoral Dissertation Fellowship. Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",

year = "2016",

month = dec,

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doi = "10.1021/acs.nanolett.6b04113",

language = "English (US)",

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T1 - Split-Wedge Antennas with Sub-5 nm Gaps for Plasmonic Nanofocusing

AU - Chen, Xiaoshu

AU - Lindquist, Nathan C.

AU - Klemme, Daniel J.

AU - Nagpal, Prashant

AU - Norris, David J.

AU - Oh, Sang Hyun

N1 - Funding Information: This research was supported by the Office of Naval Research Young Investigator Program (to X.S.C., N.C.L. and S.-H.O.), the National Science Foundation (CMMI No. 1363334 for D.J.K. and S.-H.O.; ECCS No. 1610333 for S.-H.O.; CAREER Award No. 1552642 for N.C.L.; NSF Graduate Research Fellowship for D.J.K.), Seagate Technology (MINT grant for S.-H.O.), and the MnDrive Initiative from the State of Minnesota (to D.J.K. and S.-H.O.). X.S.C. acknowledges support from the 3M Science and Technology Fellowship and the University of Minnesota Doctoral Dissertation Fellowship. Publisher Copyright: © 2016 American Chemical Society.

PY - 2016/12/14

Y1 - 2016/12/14

N2 - We present a novel plasmonic antenna structure, a split-wedge antenna, created by splitting an ultrasharp metallic wedge with a nanogap perpendicular to its apex. The nanogap can tightly confine gap plasmons and boost the local optical field intensity in and around these opposing metallic wedge tips. This three-dimensional split-wedge antenna integrates the key features of nanogaps and sharp tips, i.e., tight field confinement and three-dimensional nanofocusing, respectively, into a single platform. We fabricate split-wedge antennas with gaps that are as small as 1 nm in width at the wafer scale by combining silicon V-grooves with template stripping and atomic layer lithography. Computer simulations show that the field enhancement and confinement are stronger at the tip-gap interface compared to what standalone tips or nanogaps produce, with electric field amplitude enhancement factors exceeding 50 when near-infrared light is focused on the tip-gap geometry. The resulting nanometric hotspot volume is on the order of λ3/106. Experimentally, Raman enhancement factors exceeding 107 are observed from a 2 nm gap split-wedge antenna, demonstrating its potential for sensing and spectroscopy applications.

AB - We present a novel plasmonic antenna structure, a split-wedge antenna, created by splitting an ultrasharp metallic wedge with a nanogap perpendicular to its apex. The nanogap can tightly confine gap plasmons and boost the local optical field intensity in and around these opposing metallic wedge tips. This three-dimensional split-wedge antenna integrates the key features of nanogaps and sharp tips, i.e., tight field confinement and three-dimensional nanofocusing, respectively, into a single platform. We fabricate split-wedge antennas with gaps that are as small as 1 nm in width at the wafer scale by combining silicon V-grooves with template stripping and atomic layer lithography. Computer simulations show that the field enhancement and confinement are stronger at the tip-gap interface compared to what standalone tips or nanogaps produce, with electric field amplitude enhancement factors exceeding 50 when near-infrared light is focused on the tip-gap geometry. The resulting nanometric hotspot volume is on the order of λ3/106. Experimentally, Raman enhancement factors exceeding 107 are observed from a 2 nm gap split-wedge antenna, demonstrating its potential for sensing and spectroscopy applications.

KW - Optical antenna

KW - atomic layer deposition

KW - atomic layer lithography

KW - gap plasmon

KW - surface-enhanced Raman scattering (SERS)

KW - template stripping

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U2 - 10.1021/acs.nanolett.6b04113

DO - 10.1021/acs.nanolett.6b04113

M3 - Article

C2 - 27960527

AN - SCOPUS:85006248651

SN - 1530-6984

VL - 16

SP - 7849

EP - 7856

JO - Nano Letters

JF - Nano Letters

IS - 12

ER -

Split-Wedge Antennas with Sub-5 nm Gaps for Plasmonic Nanofocusing

Abstract

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