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Appearance of polar optical modes in raman scattering in semiconductor nanocrystals

  • A. Yu. Boikov
  • S. V. KarpovEmail author
  • S. V. Mikushev
Article
  • 41 Downloads

Abstract

The Raman spectra of nine samples of glasses with different content of CdSe semiconductor nanocrystals of different dimensions obtained by annealing samples are studied. It is established that, in the spectra of nanocrystals of all samples, there appears a line of the fundamental polar vibration whose frequency is close to that of the longitudinal optical mode of the CdSe bulk crystal. In this case, the asymmetry of this line essentially depends on the sample, the semiconductor concentration, and the local excitation place. To analyze the obtained results, a factor analysis method is used to separate linearly independent components from the data set. It is established that three or four contributions with frequencies near 180, 190, 208, and, probably, 210 cm−1 can be singled out in the contour of the line under consideration. A comparison of the obtained results with the conclusions made by using microscopic models demonstrates a significant difference between the experimental data and the results obtained by using mechanical and dielectrical continuum models. It is possible that the real picture of quantum dot vibrations is more complicated and can be described better within the microscopic model. Moreover, for a CdS nanocrystal, the experimental spectra agree satisfactorily with results of calculation of vibrations, in which 3–4 bands with a frequency difference of 10-15 cm−1 exist in the region of the LO mode for crystals with dimensions of 5 × 5 × 5 unit cells (1000 atoms).

Keywords

Raman Spectrum Surface Investigation Neutron Technique Raman Line Fundamental Vibration 
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

© Pleiades Publishing, Ltd. 2008

Authors and Affiliations

  • A. Yu. Boikov
    • 1
  • S. V. Karpov
    • 1
    Email author
  • S. V. Mikushev
    • 1
  1. 1.Fock Research Institute of PhysicsSt. Petersburg State UniversitySt. PetersburgRussia

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