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

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

  • Chen X Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
  • Lindquist NC Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
  • Klemme DJ Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
  • Nagpal P Chemical and Biological Engineering, University of Colorado , Boulder, Colorado 80303, United States.
  • Norris DJ Optical Materials Engineering Laboratory, ETH Zurich , 8092 Zurich, Switzerland.
  • Oh SH Department of Electrical and Computer Engineering, University of Minnesota , Minneapolis, Minnesota 55455, United States.
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  • 2016-12-15
Published in:
  • Nano letters. - 2016
Optical antenna
atomic layer deposition
atomic layer lithography
gap plasmon
surface-enhanced Raman scattering (SERS)
template stripping
English 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.
Language
  • English
Open access status
hybrid
Identifiers
Persistent URL
https://sonar.ch/global/documents/107922
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