Surface plasmon resonances in silicon nanowires with varying geometry

Silicon nanowires (SiNWs) are functional nanostructures for electronics in several fields such as photovoltaics, photodetectors, photocatalysis or sensing. Their synthesis can be VLS- compatible, which renders them potential candidates for large-scale applications. SiNWs exhibit unique electro-optical properties, including plasmon resonances (PRs): the collective oscillations of free electrons. An electromagnetic field can induce this phenomenon at specific frequencies, depending on the nanosystem shape and its surrounding medium. SiNWs are already used to absorb and amplify, by several orders of magnitude, radiant energy and to generate a locally amplified electric field, a beneficial mechanism in many applications. We demonstrated the longitudinal and transversal PRs in SiNWs in our recent work[1]. There is, however, no deep understanding in the literature on how the PR changes with the SiNW size. In this contribution, we report the study of the PRs triggered in SiNWs with varying diameters, pursued by high resolution electron energy loss spectroscopy, to understand how the SiNW geometry influences its plasmonic behaviour. We further support our findings with theoretical calculations to understand the PR's electric field intensity and spatial distribution upon a changing nanostructure geometry.

[1] Borgh, G., Bongiorno, C., La Magna, A., Mannino, G., Patanè, S., Adam, Jost and Puglisi, R. A., “Surface Plasmons in Silicon Nanowires” Accepted Manuscript: doi:10.1002/adpr.202100130