Effects of charged defects on the electronic and optical properties of self-assembled quantum dots

TL;DR

This study examines how point charge defects influence the electronic and optical properties of self-assembled quantum dots, revealing significant effects on spectra and electronic structure, especially in strain-free variants.

Contribution

It provides a comparative analysis of defect impacts on strained and strain-free quantum dots, highlighting differences in excitonic properties and polarization behaviors.

Findings

Charged defects significantly alter electronic structures and excitonic spectra.

Fine structure splitting and polarization are unaffected in strained quantum dots.

Strain-free quantum dots show notable changes in polarization and fine structure splitting.

Abstract

We investigate the effects of point charge defects on the single particle electronic structure, emission energies, fine structure splitting and oscillator strengths of excitonic transitions in strained In$_{0.6}$Ga$_{0.4}$As/GaAs and strain-free GaAs/Al$_{0.3}$Ga$_{0.7}$As quantum dots. We find that the charged defects significantly modify the single particle electronic structure and excitonic spectra in both strained and strain-free structures. However, the excitonic fine structure splitting, polarization anisotropy and polarization direction in strained quantum dots remain nearly unaffected, while significant changes are observed for strain-free quantum dots.