Surface Plasmons in Silicon Nanowires

Plasmon resonances (PRs) in metallic nanostructures have been extensively studied, whereas reports on PR in silicon nanowires (Si NWs) are very few, partial, and they refer to structures larger than 100nm. Discrete resonances in Si NWs with core sizes as small as 30nm at high resolution are observed. They are attributed to plasmonic resonances identifying two groups, the traveling waves, exhibiting discrete modes along the NW length for several orders of harmonics, and the localized waves, generated by transverse oscillations along the NW diameter, observing them to the best of our knowledge for the first time in silicon NWs (SiNWs) of every size. The experimental findings are coupled to modeling, confirming the data and adding further insights into the Si NW's embedding medium role. A plasmon-induced resonant cavity in Si NWs opens markets in material processing, photodetectors, and novel plasmon-based nano-optics, thanks to the intense optical energy delivery below the diffraction limit and the addition of the exceptional integration capacity of silicon.