Medium-range order in amorphous silicon investigated by constrained structural relaxation of two-body and four-body electron diffraction data

Konstantin Borisenko, Bianca Haberl, Amelia Liu, Yixin Chen, Guoqiang Li, James Williams, Jodie Bradby, David Cockayne, Michael Treacy

    Research output: Contribution to journalArticleResearchpeer-review

    26 Citations (Scopus)

    Abstract

    The structures of four types of amorphous silicon are examined by an experimentally constrained structural relaxation method (ECSR). Experimental selected area electron diffraction data and fluctuation electron microscopy normalized diffraction variance data were used as constraints to guide a Monte Carlo relaxation procedure towards best fit models. A Tersoff potential was also used to further restrict the space of possible solutions. The materials examined were self-ion-implanted silicon and pressure-amorphized silicon, both in their as-prepared and thermally annealed states. In the fitted models for these materials regions containing two types of medium-range order were identified. One type involves formation of paracrystallites with cubic and hexagonal structures, where both short-range crystalline and medium-range order are present. The other type of medium-range order appears in the form of extended crystalline planes without associated short-range crystalline order. These two types can coexist. It is observed that the best fit models for both as-prepared samples contain approximately 10-15 paracrystalline ordered regions, reducing to about 5-10 in the annealed materials. None of the models are true continuous random networks. We conclude that, with long computational times and with a suitable potential function, the ECSR procedure provides a powerful, although at present semi-quantitative, tool for determining the structural form of medium-range order in thin amorphous materials.
    Original languageEnglish
    Pages (from-to)359 - 375
    Number of pages17
    JournalActa Materialia
    Volume60
    Issue number1
    DOIs
    Publication statusPublished - 2012

    Cite this

    Borisenko, Konstantin ; Haberl, Bianca ; Liu, Amelia ; Chen, Yixin ; Li, Guoqiang ; Williams, James ; Bradby, Jodie ; Cockayne, David ; Treacy, Michael. / Medium-range order in amorphous silicon investigated by constrained structural relaxation of two-body and four-body electron diffraction data. In: Acta Materialia. 2012 ; Vol. 60, No. 1. pp. 359 - 375.
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    abstract = "The structures of four types of amorphous silicon are examined by an experimentally constrained structural relaxation method (ECSR). Experimental selected area electron diffraction data and fluctuation electron microscopy normalized diffraction variance data were used as constraints to guide a Monte Carlo relaxation procedure towards best fit models. A Tersoff potential was also used to further restrict the space of possible solutions. The materials examined were self-ion-implanted silicon and pressure-amorphized silicon, both in their as-prepared and thermally annealed states. In the fitted models for these materials regions containing two types of medium-range order were identified. One type involves formation of paracrystallites with cubic and hexagonal structures, where both short-range crystalline and medium-range order are present. The other type of medium-range order appears in the form of extended crystalline planes without associated short-range crystalline order. These two types can coexist. It is observed that the best fit models for both as-prepared samples contain approximately 10-15 paracrystalline ordered regions, reducing to about 5-10 in the annealed materials. None of the models are true continuous random networks. We conclude that, with long computational times and with a suitable potential function, the ECSR procedure provides a powerful, although at present semi-quantitative, tool for determining the structural form of medium-range order in thin amorphous materials.",
    author = "Konstantin Borisenko and Bianca Haberl and Amelia Liu and Yixin Chen and Guoqiang Li and James Williams and Jodie Bradby and David Cockayne and Michael Treacy",
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    Medium-range order in amorphous silicon investigated by constrained structural relaxation of two-body and four-body electron diffraction data. / Borisenko, Konstantin; Haberl, Bianca; Liu, Amelia; Chen, Yixin; Li, Guoqiang; Williams, James; Bradby, Jodie; Cockayne, David; Treacy, Michael.

    In: Acta Materialia, Vol. 60, No. 1, 2012, p. 359 - 375.

    Research output: Contribution to journalArticleResearchpeer-review

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    T1 - Medium-range order in amorphous silicon investigated by constrained structural relaxation of two-body and four-body electron diffraction data

    AU - Borisenko, Konstantin

    AU - Haberl, Bianca

    AU - Liu, Amelia

    AU - Chen, Yixin

    AU - Li, Guoqiang

    AU - Williams, James

    AU - Bradby, Jodie

    AU - Cockayne, David

    AU - Treacy, Michael

    PY - 2012

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    AB - The structures of four types of amorphous silicon are examined by an experimentally constrained structural relaxation method (ECSR). Experimental selected area electron diffraction data and fluctuation electron microscopy normalized diffraction variance data were used as constraints to guide a Monte Carlo relaxation procedure towards best fit models. A Tersoff potential was also used to further restrict the space of possible solutions. The materials examined were self-ion-implanted silicon and pressure-amorphized silicon, both in their as-prepared and thermally annealed states. In the fitted models for these materials regions containing two types of medium-range order were identified. One type involves formation of paracrystallites with cubic and hexagonal structures, where both short-range crystalline and medium-range order are present. The other type of medium-range order appears in the form of extended crystalline planes without associated short-range crystalline order. These two types can coexist. It is observed that the best fit models for both as-prepared samples contain approximately 10-15 paracrystalline ordered regions, reducing to about 5-10 in the annealed materials. None of the models are true continuous random networks. We conclude that, with long computational times and with a suitable potential function, the ECSR procedure provides a powerful, although at present semi-quantitative, tool for determining the structural form of medium-range order in thin amorphous materials.

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