Fowler–Nordheim Tunneling Induced Charge Transfer Plasmons between Nearly Touching Nanoparticles

Abstract

Reducing the gap between two metal nanoparticles down to atomic dimensions uncovers novel plasmon resonant modes. Of particular interest is a mode known as the charge transfer plasmon (CTP). This mode has been experimentally observed in touching nanoparticles, where charges can shuttle between the nanoparticles via a conductive path. However, the CTP mode for nearly touching nanoparticles has only been predicted theoretically to occur via direct tunneling when the gap is reduced to ~0.4 nm. Because of challenges in fabricating and characterizing gaps at these dimensions, experiments have been unable to provide evidence for this plasmon mode that is supported by tunneling. In this work, we consider an alternative tunneling process, that is, the well-known Fowler-Nordheim (FN) tunneling that occurs at high electric fields, and apply it for the first time in the theoretical investigation of plasmon resonances between nearly touching nanoparticles. This new approach relaxes the requirements on gap dimensions, and intuitively suggests that with a sufficiently high-intensity irradiation, the CTP can be excited via FN tunneling for a range of subnanometer gaps. The unique feature of FN tunneling induced CTP is the ability to turn on and off the charge transfer by varying the intensity of an external light source, and this could inspire the development of novel quantum devices.

A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations

“…We put particular emphasis in the extension of the QCM to incorporate the hydrodynamical treatment of nonlocal effects, and discuss the effect of non-zero temperatures on the optical properties. While this paper focuses on the linear response, the QCM can be extended to nonlinear phenomena 34,[127][128][129][130] by taking into account the dependence of tunneling across the gap on the strength of the local eld.…”

Quantum Plasmonics

“…An interesting idea is to use a strong electric field to enhance the tunnelling rate using Fowler Nordheim tunnelling (emission of electrons induced by an electrostatic field) [152]. Another fascinating modification to the dimer setup is to bridge the gap with suitable molecules that will increase the tunnelling distance.…”

Nonlinear Photon-Assisted Tunneling Transport in Optical Gap Antennas

“…For an atomic-scale gap, charge transfer plasmons are driving the antenna response in the so-called quantum tunneling regime [12][13][14][15]. In this regime, the quantum nature of the interaction opens a new paradigm for utilizing optical gap antennas beyond the control of electromagnetic fields at the nanometer length scale [16,17].…”