title: Enhancement of Radiative Plasmon Decay by Hot Electron Tunneling.
abstract: Here we demonstrate that photon emission induced by inelastic tunneling through a nanometer single gap between a sharp Au tip and an Au substrate can be significantly enhanced by the illumination of the junction with 634 nm laser light with an electric field component oriented parallel to the tip-axis, i.e., perpendicular to the sample. Analyzing photoluminescence (PL) spectra recorded as a function of bias voltage allows us to distinguish between PL from (1) the decay of electron-hole pairs created by the laser excited sp/d interband transition with a characteristic band at 690 nm and (2) the red-shifted radiative decay of characteristic plasmon modes formed by the gap. Since the electroluminescence spectra (without laser) already show the plasmonic gap modes, we conclude that the enhanced intensity induced by laser illumination originates from the radiative decay of hot electrons closely above the Fermi level via inelastic tunneling and photon emission into the plasmon modes. Since these processes can be independently controlled by laser illumination and the amplitude of the bias voltage, it is of great interest for designing new switchable photon emission plasmonic devices.
authors.affiliation: Institute of Physical and Theoretical Chemistry and LISA+, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wang
authors.affiliation: Institute of Physical and Theoretical Chemistry and LISA+, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Braun
authors.affiliation: Institute of Physical and Theoretical Chemistry and LISA+, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Dai
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Institute of Physical and Theoretical Chemistry and LISA+, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Peisert
authors.affiliation: Institute of Physical and Theoretical Chemistry and LISA+, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Hilmar
authors.initials: H
authors.lastname: Adler
authors.affiliation: Institute of Physical and Theoretical Chemistry and LISA+, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Chassé
authors.affiliation: Institute of Physical and Theoretical Chemistry and LISA+, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany.
authors.forename: Alfred J
authors.initials: AJ
authors.lastname: Meixner
keywords: hot electrons; inelastic electron tunneling; plasmons; tip-enhanced near-field optical microscopy