Plasmon-field-induced Metastable States in the Wetting Layer: Detected by the Fluorescence Decay Time of InAs/GaAs Single Quantum Dots

TL;DR

This paper demonstrates how plasmonic metal islands can induce long-lived metastable states in the wetting layer of InAs/GaAs quantum dots, significantly altering their fluorescence decay times and photon emission statistics.

Contribution

It introduces a novel method to control exciton emission lifetimes via plasmonic coupling with metal islands, revealing long-lived metastable states in the wetting layer.

Findings

QD lifetime increases from ~1 to 160 ns with metal islands.

Photon emission switches from antibunching to bunching due to metastable states.

Long-lived states are caused by destructive interference between dipole fields.

Abstract

We report a new way to slow down the spontaneous emission rate of excitons in the wetting layer (WL) through radiative field coupling between the exciton emissions and the dipole field of metal islands. As a result, a long-lifetime decay process is detected in the emission of InAs/GaAs single quantum dots (QDs). It is found that when the separation distance from WL layer (QD layer) to the metal islands is around 20 nm and the islands have an average size of approximately 50 nm, QD lifetime may change from approximately 1 to 160 ns. The corresponding second-order autocorrelation function g(2) ({\tau}) changes from antibunching into a bunching and antibunching characteristics due to the existence of long-lived metastable states in the WL. This phenomenon can be understood by treating the metal islands as many dipole oscillators in the dipole approximation, which may cause destructive interference between the exciton dipole field and the induced dipole field of metal islands.