title: Distinguishing between plasmon-induced and photoexcited carriers in a device geometry.
abstract: The use of surface plasmons, charge density oscillations of conduction electrons of metallic nanostructures, to boost the efficiency of light-harvesting devices through increased light-matter interactions could drastically alter how sunlight is converted into electricity or fuels. These excitations can decay directly into energetic electron-hole pairs, useful for photocurrent generation or photocatalysis. However, the mechanisms behind plasmonic carrier generation remain poorly understood. Here we use nanowire-based hot-carrier devices on a wide-bandgap semiconductor to show that plasmonic carrier generation is proportional to internal field-intensity enhancement and occurs independently of bulk absorption. We also show that plasmon-induced hot electrons have higher energies than carriers generated by direct excitation and that reducing the barrier height allows for the collection of carriers from plasmons and direct photoexcitation. Our results provide a route to increasing the efficiency of plasmonic hot-carrier devices, which could lead to more efficient devices for converting sunlight into usable energy.
authors.affiliation: Department of Electrical and Computer Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA.|Laboratory for Nanophotonics (LANP), Rice University, 6100 Main St., Houston, TX 77005, USA.
authors.forename: Bob Y
authors.initials: BY
authors.lastname: Zheng
authors.affiliation: Department of Electrical and Computer Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA.|Laboratory for Nanophotonics (LANP), Rice University, 6100 Main St., Houston, TX 77005, USA.
authors.forename: Hangqi
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Laboratory for Nanophotonics (LANP), Rice University, 6100 Main St., Houston, TX 77005, USA.|Department of Physics and Astronomy, Rice University, 6100 Main St., Houston, TX 77005, USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Manjavacas
authors.affiliation: Laboratory for Nanophotonics (LANP), Rice University, 6100 Main St., Houston, TX 77005, USA.|Department of Chemistry, Rice University, 6100 Main St., Houston, TX 77005, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: McClain
authors.affiliation: Laboratory for Nanophotonics (LANP), Rice University, 6100 Main St., Houston, TX 77005, USA.|Department of Physics and Astronomy, Rice University, 6100 Main St., Houston, TX 77005, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Nordlander
authors.affiliation: Department of Electrical and Computer Engineering, Rice University, 6100 Main St., Houston, TX 77005, USA.|Laboratory for Nanophotonics (LANP), Rice University, 6100 Main St., Houston, TX 77005, USA.|Department of Physics and Astronomy, Rice University, 6100 Main St., Houston, TX 77005, USA.|Department of Chemistry, Rice University, 6100 Main St., Houston, TX 77005, USA.
authors.forename: Naomi J
authors.initials: NJ
authors.lastname: Halas