Excitonic exchange splitting and Stokes shift in Si nanocrystals and Si clusters

Toshihide Takagahara, Kyozaburo Takeda

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    77 Citations (Scopus)

    Abstract

    The size dependence of the electron-hole exchange interaction in Si nanocrystals is investigated and the excitonic exchange splitting is predicted to be as large as 300 meV in extremely small Si clusters. The exciton-phonon interaction in Si nanocrystals for acoustic phonon modes is formulated to calculate the Stokes shift and the Huang-Rhys factor. It is found that the observed onset energy of photoluminescence can be interpreted mainly in terms of the excitonic exchange splitting, although the contribution from the Stokes shift is not negligible. The importance of the self-consistent determination of the effective dielectric constant of Si clusters including the excitonic effect is demonstrated in view of the possibility of resolving the large discrepancy between theories and experiments concerning the size dependence of the exciton energy.

    Original languageEnglish
    JournalPhysical Review B - Condensed Matter and Materials Physics
    Volume53
    Issue number8
    Publication statusPublished - 1996

    Fingerprint

    Excitons
    Nanocrystals
    nanocrystals
    excitons
    shift
    Exchange interactions
    Beam plasma interactions
    Photoluminescence
    Permittivity
    Acoustics
    interactions
    permittivity
    photoluminescence
    acoustics
    energy
    Electrons
    Experiments
    LDS 751

    ASJC Scopus subject areas

    • Condensed Matter Physics

    Cite this

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    AU - Takagahara, Toshihide

    AU - Takeda, Kyozaburo

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    N2 - The size dependence of the electron-hole exchange interaction in Si nanocrystals is investigated and the excitonic exchange splitting is predicted to be as large as 300 meV in extremely small Si clusters. The exciton-phonon interaction in Si nanocrystals for acoustic phonon modes is formulated to calculate the Stokes shift and the Huang-Rhys factor. It is found that the observed onset energy of photoluminescence can be interpreted mainly in terms of the excitonic exchange splitting, although the contribution from the Stokes shift is not negligible. The importance of the self-consistent determination of the effective dielectric constant of Si clusters including the excitonic effect is demonstrated in view of the possibility of resolving the large discrepancy between theories and experiments concerning the size dependence of the exciton energy.

    AB - The size dependence of the electron-hole exchange interaction in Si nanocrystals is investigated and the excitonic exchange splitting is predicted to be as large as 300 meV in extremely small Si clusters. The exciton-phonon interaction in Si nanocrystals for acoustic phonon modes is formulated to calculate the Stokes shift and the Huang-Rhys factor. It is found that the observed onset energy of photoluminescence can be interpreted mainly in terms of the excitonic exchange splitting, although the contribution from the Stokes shift is not negligible. The importance of the self-consistent determination of the effective dielectric constant of Si clusters including the excitonic effect is demonstrated in view of the possibility of resolving the large discrepancy between theories and experiments concerning the size dependence of the exciton energy.

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