posted on 2021-03-12, 18:39authored byLongji Cui, Yunxuan Zhu, Peter Nordlander, Massimiliano Di Ventra, Douglas Natelson
Surface
plasmon enhanced processes and hot-carrier dynamics in
plasmonic nanostructures are of great fundamental interest to reveal
light–matter interactions at the nanoscale. Using plasmonic
tunnel junctions as a platform supporting both electrically and optically
excited localized surface plasmons, we report a much greater (over
1000× ) plasmonic light emission at upconverted photon energies
under combined electro-optical excitation, compared with electrical
or optical excitation separately. Two mechanisms compatible with the
form of the observed spectra are interactions of plasmon-induced hot
carriers and electronic anti-Stokes Raman scattering. Our measurement
results are in excellent agreement with a theoretical model combining
electro-optical generation of hot carriers through nonradiative plasmon
excitation and hot-carrier relaxation. We also discuss the challenge
of distinguishing relative contributions of hot carrier emission and
the anti-Stokes electronic Raman process. This observed increase in
above-threshold emission in plasmonic systems may open avenues in
on-chip nanophotonic switching and hot-carrier photocatalysis.