Hot-carrier generation from plasmons in an antenna-spacer-mirror nanostructure

By introducing Au-nanodisk antennas, we conveniently got hot carriers from decay of surface plasmons (SPs) on planar interface in an Au-antennas/TiO₂-spacer/Au-mirror (ASM) structure without an additional phase-matching process for SP generation. The presence of hot carriers from SPs is distinguished by opposite photocurrents compared with a similar structure without an Au mirror. Analyzed by extinction spectra and electrodynamics simulations, reflection between an Au nanodisk layer and an Au mirror induces an optical response of cavity mode, which excites SPs on an Au-mirror interface and significantly enhances the light harvesting, thus leading to a relatively high hot-carrier density from SP decay. The peak of incident photon-to-electron conversion efficiencies at different wavelength also well matches the optical response of the structure.