# Plasmonic Light Emission by Inelastic Charge Transport in Ultrathin Zinc Oxide/Metal Heterostructures

## TL;DR

This paper explores how ultrathin zinc oxide and silver structures emit light through plasmonic effects, revealing how electron transport influences the process.

## Contribution

The study reveals that inelastic charge transport across ZnO/Ag(111) interfaces drives plasmonic luminescence, with ZnO's conduction band acting as the initial state.

## Key findings

- Plasmonic luminescence is spectrally filtered by ZnO layers at positive bias.
- Photon emission above ZnO's conduction band edge is suppressed.
- Spectral filtering depends on the local electronic structure and bias conditions.

## Abstract

Controlling light emission from plasmonic nanojunctions
is crucial
for developing tunable nanoscale light sources and integrated photonic
applications. It requires precise engineering of plasmonic nanocavity
electrodes and a detailed understanding of electrically driven light
emission. Using scanning tunneling microscopy-induced luminescence
(STML), we studied plasmonic light emission from ultrathin ZnO/Ag(111)
inside a silver nanocavity. At positive bias, plasmonic luminescence,
caused by radiative decay of localized surface plasmons (LSP), is
spectrally low-pass filtered by the ZnO layers. The emission of photon
energies above the conduction band edge energy (ECB) of ZnO is suppressed, while the
spectral distribution below ECB resembles the LSP resonance on Ag(111). This spectral
filtering is absent at negative bias and depends on the local electronic
structure, as confirmed by spatial STML mapping. Our findings demonstrate
that the ZnO conduction band serves as the initial state for plasmonic
luminescence driven by inelastic electron transport across the ZnO/Ag(111)
interface.