Single-particle-picture breakdown in laterally weakly confining GaAs quantum dots

Daniel Huber,Saimon Filipe Covre Da Silva,Petr Klenovský,Simon Schuler,Barbara Ursula Lehner,Armando Rastelli,Diana Csontosová,Marcus Reindl

doi:10.1103/physrevb.100.235425

Abstract

We present a detailed investigation of different excitonic states weakly confined in single GaAs/AlGaAs quantum dots obtained by the Al droplet-etching method. For our analysis we make use of temperature-, polarization- and magnetic field-dependent $\mu$-photoluminescence measurements, which allow us to identify different excited states of the quantum dot system. Besides that, we present a comprehensive analysis of g-factors and diamagnetic coefficients of charged and neutral excitonic states in Voigt and Faraday configuration. Supported by theoretical calculations by the Configuration interaction method, we show that the widely used single-particle Zeeman Hamiltonian cannot be used to extract reliable values of the g-factors of the constituent particles from excitonic transition measurements.

Highlights

We present a detailed investigation of different excitonic states weakly confined in single GaAs/AlGaAs quantum dots obtained by the Al droplet-etching method
The knowledge of the magneto-optical properties of GaAs/AlGaAs quantum dots (QDs) obtained by droplet etching is restricted to only a few works [25,26,27], and a comprehensive analysis is to the best of our knowledge missing
We begin by characterizing the optical transitions of our GaAs/AlGaAs QDs

Summary

INTRODUCTION

Within the past few years, GaAs quantum dots (QDs), obtained with the droplet-etching method [1,2,3], emerged as a promising source of nonclassical states of light, such as single photons with a strongly suppressed multiphoton emission probability [4], highly indistinguishable photon states [5,6,7,8], and single polarization entangled photon-pairs with a near unity degree of entanglement [5,9,10,11] Recently was it realized that excitons must be weakly confined in these QDs, as the measured ground-state exciton (X ) lifetimes of about 250 ps [5,9,10] are significantly lower than the minimum lifetime expected for a strongly confining system (440 ps) [6,12]. We demonstrate by experiment and CI calculations that a SP picture, which turns out to be adequate in the case of strongly confining QDs, leads to poor results in a weakly confining system [21,24,32]

Polarization-resolved and temperature-dependent μ-PL measurements

Magneto-optical properties of GaAs QDs

CONFIGURATION-INTERACTION CALCULATIONS

CONCLUSION