Publication detail

Spontaneous brightening of dark excitons in GaAs/AlGaAs quantum dots near a cleaved facet

HUO, Y. KŘÁPEK, V. SCHMIDT, O. RASTELLI, A.

Original Title

Spontaneous brightening of dark excitons in GaAs/AlGaAs quantum dots near a cleaved facet

Type

journal article in Web of Science

Language

English

Original Abstract

Dark excitons (DEs) confined in epitaxial quantum dots (QDs) are interesting because of their long lifetime compared to bright excitons (BEs). For the same reason they are usually difficult to access in optical experiments. Here we report on the observation of vertically polarized light emission from DEs confined in high-quality epitaxial GaAs/AlGaAs QDs located in proximity of a cleaved facet of the QD specimen. Calculations based on the eight-band k·p method and configuration interaction allow us to attribute the brightening of the DE to the anisotropic strain present at the sample edge, which breaks the symmetry of the system and enhances valence-band mixing. The mechanism of DE brightening is discussed in detail by inspecting both the Bloch and envelope wave functions of the involved hole states. In addition, by investigating experimentally and theoretically QDs with different sizes, we find that the energy separation between DE and BEs tends to decrease with increasing QD height. Finally, the presence of a cleaved facet is found also to enhance the BE fine structure splitting. This work provides a simple method to optically probe dark excitonic states in QDs and shows that the properties of QDs can be significantly affected by the presence of nearby edges.

Keywords

dark excitons; quantum dots;

Authors

HUO, Y.; KŘÁPEK, V.; SCHMIDT, O.; RASTELLI, A.

Released

27. 4. 2017

ISBN

0163-1829

Periodical

PHYSICAL REVIEW B

Year of study

95

Number

16

State

United States of America

Pages from

1

Pages to

8

Pages count

8

URL

https://doi.org/10.1103/PhysRevB.95.165304

BibTex

@article{BUT135512,
  author="Y.H. {Huo} and Vlastimil {Křápek} and O.G. {Schmidt} and A. {Rastelli}",
  title="Spontaneous brightening of dark excitons in GaAs/AlGaAs quantum dots near a cleaved facet",
  journal="PHYSICAL REVIEW B",
  year="2017",
  volume="95",
  number="16",
  pages="1--8",
  doi="10.1103/PhysRevB.95.165304",
  issn="0163-1829",
  url="https://doi.org/10.1103/PhysRevB.95.165304"
}