Surface Plasmon Based Engineering of Semiconductor Nanowire Optics*

Emission from unthermalized (hot) excitons can be observed from high-quality crystals and quantum-well structures due to decreases in the exciton lifetimes but typically with low yields. By employing a plasmonic nanocavity, we observe efficient hot-exciton emission in core-shell CdS-SiO$_{2}$-Ag nanowires with intensities surpassing those from thermalized excitons [1]. These new spectral characteristics are mediated by whispering gallery plasmonic modes that yield highly intense electromagnetic fields. As a result, the exciton radiative lifetime is decreased by several orders of magnitude. The introduction of a high-quality hybrid plasmonic nanocavity structure significantly changes the photophysics of the host material, demonstrating an approach applicable to other material systems. \\[4pt] [1] Chang-Hee Cho, \textit{et al}, Nature Materials, \textbf{10}, 669 (2011).