Semiconductor nanowire plasmonics
Surface plasmons enable the confinement and transport of light in deep-subwavelength volumes. Noble metals offer this extraordinary capability in the visible/near-infrared, yielding extreme chemical sensitivity (e.g., surface enhanced Raman scattering), high resolution near-field imaging, compact waveguides, and more. However, conventional metals cannot support truly localized surface plasmon resonances (LSPRs) at mid-/far-infrared wavelengths since they become nearly perfect conductors.
Nanoscale semiconductors are emerging as alternative, more flexible materials for manipulating light-matter interactions in the infrared. The tunability of semiconductor permittivity via chemical doping and/or electrostatic gating is central to their promise. Vapor-liquid-solid growth of semiconductor nanowires, which offers nanoscale control of dopant profile, provides an intriguing route to engineer both near- and far-field optical response. We are synthesizing and characterizing a range of plasmonic semiconductor nanowires with the goal of enabling narrowband infrared light sources, compact thermal waveguides, and ultrasensitive chemical sensors.