Analysis of Emission Dynamics of a Long Lifetime in Single InAs/GaAs Quantum Dots

TL;DR

This paper introduces a three-level model to simulate the long lifetime emission decay in single InAs/GaAs quantum dots, capturing the non-single exponential decay and auto-correlation behavior with analytical formulas.

Contribution

A novel three-level model is proposed to accurately describe emission decay and auto-correlation in quantum dots with long-lived metastable states.

Findings

The model fits experimental decay curves well.

Derived analytical expression for average lifetime.

Successfully modeled second-order auto-correlation function.

Abstract

A very long lifetime emission with non-single exponential decay characteristic has been reported for single InAs/GaAs quantum dot (QD) samples, in which there exists a long-lived metastable state in the wetting layer (WL) [ACS Photonics 2020,7,3228-3235]. In this article we have proposed a new three-level model to simulate the emission decay curve. In this model, assuming that the excitons in metastable state will diffuse and be trapped by QDs, and then emit fluorescence in QDs, a stretched-like exponential decay formula is derived as I(t)=At^({\beta}-1)e^(-(rt)^{\beta}), which can well describe the long lifetime decay curve with an analytical expression of average lifetime <{\tau}>=1/r{\Gamma}(1/{\beta}+1), where {\Gamma} is the Gamma function. Furthermore, based on the proposed three-level model, an expression of the second-order auto-correlation function g^2 (t) which can well fit the measured g^2 (t) curve is also obtained.