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) |
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Pages (from-to) | 7849-7856 |
Number of pages | 8 |
Journal | Nano letters |
Volume | 16 |
Issue number | 12 |
DOIs | |
State | Published - Dec 14 2016 |
Bibliographical note
Publisher Copyright:© 2016 American Chemical Society.
Keywords
- Optical antenna
- atomic layer deposition
- atomic layer lithography
- gap plasmon
- surface-enhanced Raman scattering (SERS)
- template stripping