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

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


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.


Refraction LaF3 Oxyfluoride 


  1. 1.
    Ekimov A.I. etal // JOSA (B). 1993. V.10. P.100.CrossRefGoogle Scholar
  2. 2.
    Vasilevskiy M.I. et al // phys. stat. sol. (b) 2001. V.224. • 5.CrossRefGoogle Scholar
  3. 3.
    Roca E., Trallero-Gmer C. and Cardona M. // Phys. Rev. B. 1994. V.49. P.13704.CrossRefGoogle Scholar
  4. 4.
    Milekhin A., Friedrich M., Zahn D.R.T., Sveshnikova L., and Repinsky S. // Appl. Phys. A. 1999. V.69. P.97.CrossRefGoogle Scholar
  5. 5.
    Vasilevskiy M.I., Akinkina E.I., de Paula A.M. and Anda E.V. // Semiconductors. 1998. V.32. P.1229.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2003

Authors and Affiliations

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

Personalised recommendations