title: Plasmonic Heating in Au Nanowires at Low Temperatures: The Role of Thermal Boundary Resistance.
abstract: Inelastic electron tunneling and surface-enhanced optical spectroscopies at the molecular scale require cryogenic local temperatures even under illumination-conditions that are challenging to achieve with plasmonically resonant metallic nanostructures. We report a detailed study of the laser heating of plasmonically active nanowires at substrate temperatures from 5 to 60 K. The increase of the local temperature of the nanowire is quantified by a bolometric approach and could be as large as 100 K for a substrate temperature of 5 K and typical values of laser intensity. We also demonstrate that a ∼3-fold reduction of the local temperature increase is possible by switching to a sapphire or quartz substrate. Finite element modeling of the heat dissipation reveals that the local temperature increase of the nanowire at temperatures below ∼50 K is determined largely by the thermal boundary resistance of the metal-substrate interface. The model reproduces the striking experimental trend that in this regime the temperature of the nanowire varies nonlinearly with the incident optical power. The thermal boundary resistance is demonstrated to be a major constraint on reaching low temperatures necessary to perform simultaneous inelastic electron tunneling and surface-enhanced Raman spectroscopies.
authors.affiliation: Department of Physics and Astronomy, ‡Department of Electrical and Computer Engineering, and §Department of Materials Science and NanoEngineering, Rice University , 6100 Main Street, Houston, Texas 77005, United States.
authors.forename: Pavlo
authors.initials: P
authors.lastname: Zolotavin
authors.affiliation: Department of Physics and Astronomy, ‡Department of Electrical and Computer Engineering, and §Department of Materials Science and NanoEngineering, Rice University , 6100 Main Street, Houston, Texas 77005, United States.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Alabastri
authors.affiliation: Department of Physics and Astronomy, ‡Department of Electrical and Computer Engineering, and §Department of Materials Science and NanoEngineering, Rice University , 6100 Main Street, Houston, Texas 77005, United States.
authors.forename: Peter
authors.initials: P
authors.lastname: Nordlander
authors.affiliation: Department of Physics and Astronomy, ‡Department of Electrical and Computer Engineering, and §Department of Materials Science and NanoEngineering, Rice University , 6100 Main Street, Houston, Texas 77005, United States.
authors.forename: Douglas
authors.initials: D
authors.lastname: Natelson
keywords: laser heating; low temperatures; molecular junctions; nanowire; plasmon; plasmon damping; thermal boundary resistance; thermoplasmonics