Probing energy transfer in an ensemble of silicon nanocrystals

H. Jayatilleka, D. Diamare, M. Wojdak, A. J. Kenyon, C. R. Mokry, P. J. Simpson, A. P. Knights, I. Crowe, M. P. Halsall

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Time-resolved photoluminescence measurements of silicon nanocrystals formed by ion implantation of silicon into silicon dioxide reveal multi-exponential luminescence decays. Three discrete time components are apparent in the rise and decay data, which we associate with different classes of nanocrystals. The values of decay time are remarkably constant with emission energy, but the relative contributions of the three components vary strongly across the luminescence band. In keeping with the quantum confinement model for luminescence, we assign emission at high energies to small nanocrystals and that at low energies to large nanocrystals. By deconvolving the decay data over the full emission band, it is possible to study the migration of excitation from smaller (luminescence donor) to larger (luminescence acceptor) nanocrystals. We propose a model of diffusion of excitation between neighboring nanocrystals, with long lifetime emission being from the largest nanocrystal in the local neighborhood. Our data also allow us to study the saturation of acceptor nanocrystals, effectively switching off excitation transfer, and Auger recombination in non-interacting nanocrystals. © 2011 American Institute of Physics.
    Original languageEnglish
    Article number033522
    JournalJournal of Applied Physics
    Volume110
    Issue number3
    DOIs
    Publication statusPublished - 1 Aug 2011

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