Spectral Tuning of Plasmonic Activity in 3D Nanostructures via High-Precision Nano-Printing

Plasmonic nanoparticles reveal unique optical properties and are increasingly incorporated into commercial products and technologies, ranging from photovoltaics to biological and chemical sensors. Shifting and tuning their plasmonic response according to the targeted application strongly depends on the ability to control the geometry in every detail and has not been reliably demonstrated for complex 3D nano-architectures yet. Following that motivation, it herein presents how Focused Electron Beam Induced Deposition (FEBID), a highly flexible additive 3D direct-write technology with spatial nano-scale precision, is used for the controlled and tunable fabrication of plasmonically active 3D nanostructures that exhibit highly concentrated, well defined and predictable local plasmonic resonances. As model systems, planar Au nanowires and 3D nano-tips of various geometries are prepared via FEBID and plasmonically characterized via scanning transmission electron microscopy based electron energy loss spectroscopy (STEM-EELS) mapping measurements. The findings are complemented with corresponding plasmon simulations, revealing very good agreement with experimental findings. This way, on-demand spectral tuning of the plasmonic response becomes accessible via upfront modeling and design of suitable 3D nanostructures, to achieve customized plasmonic responses, therefore paving the way for yet unrealized plasmonic applications in 3D space.