Nanoscale semiconductors are emerging as promising plasmonic materials for applications in the infrared. Herein, we study the near-field coupling between adjacent plasmonic resonators embedded in Si nanowires with in-situ infrared spectroscopy and discrete dipole approximation calculations. Si nanowires containing multiple phosphorus-doped segments, each with a user-programmable aspect ratio and carrier density, are synthesized via the vapor-liquid- solid technique and support localized surface plasmon resonances (LSPRs) between 5 and 10 μm. Discrete dipole approximation calculations confirm that the observed spectral response results from resonant absorption and free carrier concentrations are on the order of 10²⁰ cm^-3. Near-field coupling occurs between neighboring doped segments and the observed trends agree with plasmon hybridization theory. Our results highlight the utility of vapor-liquid-solid (VLS) synthesis for investigating the basic physics of surface plasmons in nanoscale semiconductors and suggest new opportunities for engineering light absorption in Si.

Date Published: 11 September 2013
PDF: 8 pages
Proc. SPIE 8809, Plasmonics: Metallic Nanostructures and Their Optical Properties XI, 88091R (11 September 2013); doi: 10.1117/12.2024216

Published in SPIE Proceedings Vol. 8809:
Plasmonics: Metallic Nanostructures and Their Optical Properties XI
Mark I. Stockman, Editor(s)