Ultrafast terahertz conductivity of photoexcited nanocrystalline silicon

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


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.


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