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Dipole-Dipole Interaction Effect on the Optical Response of Quantum Dot Ensembles

  • S. A. Filonovich
Chapter
Part of the NATO Science Series book series (NAII, volume 90)

Abstract

Semiconductors quantum dots (QDs) possess discrete excitonic and phonon spectra. For a spherical QD of radius R, the excitonic spectrum in the effective mass approximation (EMA) is well known [1]. Quantization of dipole-active optical phonons in very small crystals has received much less attention. Usually it is assumed that, for a spherical QD, there is only one far-infrared (FIR) active mode corresponding to a uniform polarization of the sphere, called the Fröhlich mode. Its frequency does not depend on the sphere’s radius. This is approximately correct if the QD radius exceeds 2-3 ran for II-VI materials like CdS and CdSe. For smaller QDs, the quantization of phonon modes is important. As it has been shown theoretically and experimentally in [2], FIR absorption spectrum of such a QD is constituted by a set of (homogeneously broadened) peaks at certain frequencies within the reststrahlen band of the bulk material. These phonon frequencies in function of the QD size can be calculated within a continuum approach similar to the EMA [3] or numerically.

Keywords

Effective Mass Approximation Uniform Polarization Excitonic Spectrum Oxyfluoride Glass Ceramic Fluorescence Line Narrowing 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media Dordrecht 2003

Authors and Affiliations

  • S. A. Filonovich
    • 1
  1. 1.Universidade do MinhoBraga

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