Midinfrared absorption of PbSe/Pb1xEuxTe quantum dot superlattices in IV-VI microcavities

T. Schwarzl, W. Heiss, G. Springholz, H. Krenn, T. Fromherz, A. Raab, and I. Vavra
Phys. Rev. B 65, 245321 – Published 21 June 2002
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Abstract

The midinfrared absorption of highly ordered self-assembled PbSe/Pb1xEuxTe quantum dot superlattices is investigated. A different approach is used for quantitative determination of the absorption spectrum of the dot superlattice by inserting it into a high-finesse microcavity structure with a small mode spacing and Pb1xEuxTe/EuTe Bragg mirrors. For such microcavities, we show a linear relation between the width of each cavity resonance and the extinction coefficient at the resonance energy. Thus, the absorption spectrum is experimentally determined from the resonance widths. It reveals a narrow peak arising from the quantum dots and a step from the two-dimensional wetting layers. The peak absorption coefficient of the dot ensemble amounts to 2.5×104cm1 and is similar to that of the wetting layers. We also present calculations of the dispersion of the absorption coefficient based on model dielectric functions of quantum dots and wetting layers. From a fit to the experimental absorption spectrum, we deduce interband transition energies as well as corresponding oscillator strengths and level broadenings. The broadening of the dot transition due to dot size fluctuations of the large quantum dot ensemble is only 8.7 meV, confirming the exceptionally high dot size uniformity in the PbSe quantum dot superlattice.

  • Received 20 February 2002

DOI:https://doi.org/10.1103/PhysRevB.65.245321

©2002 American Physical Society

Authors & Affiliations

T. Schwarzl1,*, W. Heiss1, G. Springholz1, H. Krenn2, T. Fromherz1, A. Raab1, and I. Vavra3

  • 1Institut für Halbleiter- und Festkörperphysik, Johannes Kepler Universität Linz, Altenbergerstraße 69, A-4040 Linz, Austria
  • 2Institut für Experimentalphysik, Karl-Franzens-Universität Graz, Universitätsplatz 5, A-8010 Graz, Austria
  • 3Institute of Electrical Engineering, Slovak Academy of Sciences, 842 39 Bratislava, Slovakia

  • *Corresponding author. Email address: thomas.schwarzl@jku.at

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Vol. 65, Iss. 24 — 15 June 2002

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