title: Tunable mid-infrared localized surface plasmon resonances in silicon nanowires.
abstract: We observe and systematically tune an intense mid-infrared absorption mode that results from phosphorus doping in silicon nanowires synthesized via the vapor-liquid-solid technique. The angle- and shape-dependence of this spectral feature, as determined via in-situ transmission infrared spectroscopy, supports its assignment as a longitudinal localized surface plasmon resonance (LSPR). Modulation of resonant frequency (740-1620 cm(-1)) is accomplished by varying nanowire length (135-1160 nm). The observed frequency shift is consistent with Mie-Gans theory, which indicates electrically active dopant concentrations between 10(19) and 10(20) cm(-3). Our findings suggest new opportunities to confine light in this ubiquitous semiconductor and engineer the optical properties of nontraditional plasmonic materials.
authors.affiliation: School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors.forename: Li-Wei
authors.initials: LW
authors.lastname: Chou
authors.forename: Naechul
authors.initials: N
authors.lastname: Shin
authors.forename: Saujan V
authors.initials: SV
authors.lastname: Sivaram
authors.forename: Michael A
authors.initials: MA
authors.lastname: Filler