### 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 language | English |
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Journal | Physical Review B Condensed Matter |

Volume | 82 |

Pages (from-to) | 233302 |

ISSN | 0163-1829 |

DOIs | |

Publication status | Published - 2010 |

## Cite this

Stobbe, S., Schlereth, T. W., Höfling, S., Forchel, A., Hvam, J. M., & Lodahl, P. (2010). Large quantum dots with small oscillator strength.

*Physical Review B Condensed Matter*,*82*, 233302. https://doi.org/10.1103/PhysRevB.82.233302