Radiative lifetime of excitonic photoluminescence in amorphous semiconductors

Jai Singh, I OH

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    A comprehensive theory for calculating the radiative lifetime of excitons in amorphous semiconductors is presented. Four possibilities for the radiative recombination of an exciton are considered: (i) both excited electron and hole are in their extended states, (ii) electron is in the extended and hole in tail states, (iii) electron is in the tail and hole in extended states and (iv) both in their tail states. Rates of radiative recombination corresponding to each of the four possibilities are derived: (a) within two-level approximation, and at (b) nonequilibrium and (c) equilibrium conditions. It is found that rates derived under the nonequilibrium condition have no finite peak values with respect to the photoluminescence energy. However, considering that the maximum value of a rate derived at equilibrium gives the inverse of the radiative lifetime, the latter is calculated for all the four possibilities in a-Si:H. The radiative lifetime of excitons is found to be in the ns time range for possibilities (i)-(iii) at temperatures 15-20 K and in the ?s range at 3.7 K. When the recombination occurs from the tail states, the radiative lifetime gets prolonged due to the localization of charge carriers. Results agree very well with experiments and are compared with other theories as well. � 2005 American Institute of Physics.
    Original languageEnglish
    Pages (from-to)63516.1-63516.14
    JournalJournal of Applied Physics
    Volume97
    Issue number6
    Publication statusPublished - 2005

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    amorphous semiconductors
    radiative lifetime
    photoluminescence
    excitons
    radiative recombination
    electron states
    nonequilibrium conditions
    charge carriers
    physics
    approximation
    electrons
    temperature
    energy

    Cite this

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    title = "Radiative lifetime of excitonic photoluminescence in amorphous semiconductors",
    abstract = "A comprehensive theory for calculating the radiative lifetime of excitons in amorphous semiconductors is presented. Four possibilities for the radiative recombination of an exciton are considered: (i) both excited electron and hole are in their extended states, (ii) electron is in the extended and hole in tail states, (iii) electron is in the tail and hole in extended states and (iv) both in their tail states. Rates of radiative recombination corresponding to each of the four possibilities are derived: (a) within two-level approximation, and at (b) nonequilibrium and (c) equilibrium conditions. It is found that rates derived under the nonequilibrium condition have no finite peak values with respect to the photoluminescence energy. However, considering that the maximum value of a rate derived at equilibrium gives the inverse of the radiative lifetime, the latter is calculated for all the four possibilities in a-Si:H. The radiative lifetime of excitons is found to be in the ns time range for possibilities (i)-(iii) at temperatures 15-20 K and in the ?s range at 3.7 K. When the recombination occurs from the tail states, the radiative lifetime gets prolonged due to the localization of charge carriers. Results agree very well with experiments and are compared with other theories as well. � 2005 American Institute of Physics.",
    keywords = "Amorphous semiconductors, Excitation density, Nonthermal equilibrium, Photoluminescence energy, Amorphous materials, Charge carriers, Computer simulation, Excitons, Low temperature effects, Phonons, Photoluminescence, Refractive index, Spontaneous emission, Semiconductor materials",
    author = "Jai Singh and I OH",
    year = "2005",
    language = "English",
    volume = "97",
    pages = "63516.1--63516.14",
    journal = "Journal of Applied Physics",
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    publisher = "American Institute of Physics",
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    }

    Radiative lifetime of excitonic photoluminescence in amorphous semiconductors. / Singh, Jai; OH, I.

    In: Journal of Applied Physics, Vol. 97, No. 6, 2005, p. 63516.1-63516.14.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Radiative lifetime of excitonic photoluminescence in amorphous semiconductors

    AU - Singh, Jai

    AU - OH, I

    PY - 2005

    Y1 - 2005

    N2 - A comprehensive theory for calculating the radiative lifetime of excitons in amorphous semiconductors is presented. Four possibilities for the radiative recombination of an exciton are considered: (i) both excited electron and hole are in their extended states, (ii) electron is in the extended and hole in tail states, (iii) electron is in the tail and hole in extended states and (iv) both in their tail states. Rates of radiative recombination corresponding to each of the four possibilities are derived: (a) within two-level approximation, and at (b) nonequilibrium and (c) equilibrium conditions. It is found that rates derived under the nonequilibrium condition have no finite peak values with respect to the photoluminescence energy. However, considering that the maximum value of a rate derived at equilibrium gives the inverse of the radiative lifetime, the latter is calculated for all the four possibilities in a-Si:H. The radiative lifetime of excitons is found to be in the ns time range for possibilities (i)-(iii) at temperatures 15-20 K and in the ?s range at 3.7 K. When the recombination occurs from the tail states, the radiative lifetime gets prolonged due to the localization of charge carriers. Results agree very well with experiments and are compared with other theories as well. � 2005 American Institute of Physics.

    AB - A comprehensive theory for calculating the radiative lifetime of excitons in amorphous semiconductors is presented. Four possibilities for the radiative recombination of an exciton are considered: (i) both excited electron and hole are in their extended states, (ii) electron is in the extended and hole in tail states, (iii) electron is in the tail and hole in extended states and (iv) both in their tail states. Rates of radiative recombination corresponding to each of the four possibilities are derived: (a) within two-level approximation, and at (b) nonequilibrium and (c) equilibrium conditions. It is found that rates derived under the nonequilibrium condition have no finite peak values with respect to the photoluminescence energy. However, considering that the maximum value of a rate derived at equilibrium gives the inverse of the radiative lifetime, the latter is calculated for all the four possibilities in a-Si:H. The radiative lifetime of excitons is found to be in the ns time range for possibilities (i)-(iii) at temperatures 15-20 K and in the ?s range at 3.7 K. When the recombination occurs from the tail states, the radiative lifetime gets prolonged due to the localization of charge carriers. Results agree very well with experiments and are compared with other theories as well. � 2005 American Institute of Physics.

    KW - Amorphous semiconductors

    KW - Excitation density

    KW - Nonthermal equilibrium

    KW - Photoluminescence energy

    KW - Amorphous materials

    KW - Charge carriers

    KW - Computer simulation

    KW - Excitons

    KW - Low temperature effects

    KW - Phonons

    KW - Photoluminescence

    KW - Refractive index

    KW - Spontaneous emission

    KW - Semiconductor materials

    M3 - Article

    VL - 97

    SP - 63516.1-63516.14

    JO - Journal of Applied Physics

    JF - Journal of Applied Physics

    SN - 0021-8979

    IS - 6

    ER -