Probing the Electrical Switching of a Memristive Optical Antenna by STEM EELS

TL;DR

This paper introduces a novel electro-optical switching mechanism in a nanometer-scale junction that enables active tuning of plasmonic antennas with extremely small active volume, overcoming diffraction limits in photonics.

Contribution

It demonstrates a new solid-state electro-optical switching method using atom displacement in a nanoscale gap, with detailed analysis via STEM EELS.

Findings

Switching mechanism operates in the visible range with <5 nm^3 active volume.

Electrical and optical measurements confirm the formation of conductive channels.

EELS analysis reveals the optical behavior of the plasmonic tuning.

Abstract

The scaling of active photonic devices to deep-submicron length-scales has been hampered by the fundamental diffraction limit and the absence of materials with sufficiently strong electro-optic effects. Here, we demonstrate a solid state electro-optical switching mechanism that can operate in the visible spectral range with an unparalleled active volume of less than 5 nm cube, comparable to the size of the smallest electronic components. The switching mechanism relies on electrochemically displacing metal atoms inside the nanometer-scale gap to electrically connect two crossed metallic wires forming a crosspoint junction. Such junctions afford extreme light concentration and display singular optical behavior upon formation of a conductive channel. We illustrate how this effect can be used to actively tune the resonances of plasmonic antennas. The tuning mechanism is analyzed using a combination of electrical and optical measurements as well as electron energy loss (EELS) in a scanning transmission electron microscope (STEM).