Ultrafast carrier dynamics in silicon nanocrystal films

  1. Get@NRC: Ultrafast carrier dynamics in silicon nanocrystal films (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1149/1.3700406
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Proceedings titleNanoscale Luminescent Materials 2
Series titleECS Transactions; Volume 45
Conference2nd International Symposium on Nanoscale Luminescent Materials - 221st ECS Meeting, May 6-10, 2012, Seattle, WA, USA
Pages2129; # of pages: 9
SubjectCarrier localization; Drude models; Filling fractions; Interface defects; Interface scattering; Nanocrystal sizes; Optical emissions; Percolation thresholds; Photoexcited carriers; Picosecond time scale; Si nanocrystal; Silicon nanocrystals; Thz spectroscopy; Time variations; Time-resolved; Time-scales; Ultrafast carrier dynamics; Nanocrystals; Nanotechnology; Optical waveguides; Percolation (computer storage); Percolation (fluids); Photoexcitation; Silicon; Interfaces (materials)
AbstractWe have applied time-resolved THz spectroscopy to probe the transient photoexcited carrier dynamics and THz conductivity in Si nanocrystal films with varying silicon volume filling fractions and nanocrystal sizes on picosecond time scales. The THz conductivity reveals microscopic carrier motion with significant interface scattering within nanocrystals as well as percolative transport between nanocrystals. The time variation of the THz conductivity is analyzed within the framework of the Drude-Smith model, an extension of the Drude model that characterizes carrier localization in nanostructured materials. Below the percolation threshold, transport between nanocrystals is inhibited and photoexcited carriers are localized within individual nanocrystals. These films also exhibit efficient optical emission. In films with Si filling fractions above the percolation threshold, photoluminescence is suppressed and a transition from long-range inter-nanocrystal transport immediately after photoexcitation to increased carrier localization over a 50 ps time scale due to accumulation of charges at interface defect sites is observed.
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AffiliationNational Research Council Canada (NRC-CNRC); Security and Disruptive Technologies
Peer reviewedYes
NPARC number21270221
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Record identifier1af14a35-2335-46d8-b840-ba89897c326b
Record created2014-01-13
Record modified2016-05-09
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