Tuning light emission crossovers in atomic-scale aluminum plasmonic tunnel junctions

TL;DR

This study demonstrates how tuning the conductance of atomic-scale aluminum tunnel junctions controls the dominant light emission mechanism, significantly enhancing photon yields and aligning experimental results with theoretical predictions.

Contribution

It introduces a method to tune light emission mechanisms in atomic-scale aluminum tunnel junctions by adjusting tunneling conductance, with quantitative agreement to theory.

Findings

Tuning conductance switches emission mechanisms.

Photon yields increase by two orders of magnitude.

Emission mechanism depends on tunneling rate and plasmonic properties.

Abstract

Atomic sized plasmonic tunnel junctions are of fundamental interest, with great promise as the smallest on-chip light sources in various optoelectronic applications. Several mechanisms of light emission in electrically driven plasmonic tunnel junctions have been proposed, from single-electron or higher order multi-electron inelastic tunneling to recombination from a steady-state population of hot carriers. By progressively altering the tunneling conductance of an aluminum junction, we tune the dominant light emission mechanism through these possibilities for the first time, finding quantitative agreement with theory in each regime. Improved plasmonic resonances in the energy range of interest increase photon yields by two orders of magnitude. These results demonstrate that the dominant emission mechanism is set by a combination of tunneling rate, hot carrier relaxation timescales, and junction plasmonic properties.