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Ultrafast terahertz conductivity of photoexcited nanocrystalline silicon

  • David G. Cooke
  • A. Nicole MacDonald
  • Aaron Hryciw
  • Al Meldrum
  • Juan Wang
  • Q. Li
  • Frank A. Hegmann
Article

Abstract

The ultrafast transient ac conductivity of nanocrystalline silicon films is investigated using time-resolved terahertz spectroscopy. While epitaxial silicon on sapphire exhibits a free carrier Drude response, silicon nanocrystals embedded in glass show a response that is best described by a classical Drude–Smith model, suitable for disorder-driven metal–insulator transitions. In this work, we explore the time evolution of the frequency dependent complex conductivity after optical injection of carriers on a picosecond time scale. Furthermore, we show the lifetime of photoconductivity in the silicon nanocrystal films is dominated by trapping at the Si/SiO2 interface states, occurring on a 1–100 ps time scale depending on particle size and hydrogen passivation.

Keywords

Optical Injection Picosecond Time Scale Photoconductive Decay Smith Model Energy Filter Transmission Electron Microscopy 
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.

Notes

Acknowledgments

The authors thank J. Gao for the Cr/Au electrode deposition and acknowledge helpful discussions with N. V. Smith, F. Marsiglio and A. Slepkov, and financial support from NSERC, CIPI, and iCORE.

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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • David G. Cooke
    • 1
    • 2
  • A. Nicole MacDonald
    • 1
  • Aaron Hryciw
    • 1
  • Al Meldrum
    • 1
  • Juan Wang
    • 3
  • Q. Li
    • 3
  • Frank A. Hegmann
    • 1
  1. 1.Department of PhysicsUniversity of AlbertaEdmontonCanada
  2. 2.COM·DTUTechnical University of DenmarkKgs. LyngbyDenmark
  3. 3.Department of PhysicsThe Chinese University of Hong KongShatinHong Kong

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