Plasmonic Nanoantennae with Ultrasmall Gaps and Their Application in Surface Enhanced Raman Scattering

Using direct focused ion beam milling lithography, we show fabrication of plasmonic nanoantennae with ultrasmall inter-particle separations and different outlines. Ultrasmall gap widths are achieved by appropriately aligning coaxial apertures during the milling process. The absorbance of the fabricated nanoantennae is experimentally characterized. As an important application, surface enhanced Raman scattering is demonstrated since such densely packed plasmonic nanoantennae with ultrasmall gaps can enable strong field enhancement, leading to important potential in nanophotonics and integrated optics.