Large quantum dots with small oscillator strength

S. Stobbe*, T. W. Schlereth, Sven Höfling, A. Forchel, J. M. Hvam, P. Lodahl

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)

Abstract

We have measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface. The size of the quantum dots is measured by in-plane transmission electron microscopy and we find average in-plane diameters of 40 nm. We have calculated the oscillator strength of excitons of that size assuming a quantum-dot confinement given by a parabolic in-plane potential and a hard-wall vertical potential and predict a very large oscillator strength due to Coulomb effects. This is in stark contrast to the measured oscillator strength, which turns out to be so small that it can be described by excitons in the strong confinement regime. We attribute these findings to exciton localization in local potential minima arising from alloy intermixing inside the quantum dots.

Original languageEnglish
Article number233302
Number of pages4
JournalPhysical Review. B, Condensed matter and materials physics
Volume82
Issue number23
DOIs
Publication statusPublished - 16 Dec 2010

Keywords

  • SPONTANEOUS-EMISSION
  • MICROCAVITY
  • SYSTEM
  • BOXES

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