Femtosecond studies of photoinduced bleaching and hot carrier dynamics in a-Si:H and a-Ge:H

M. Wraback, J. Tauc, D. Pang, W. Paul, J. K. Lee, E. A. Schiff

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6 Scopus citations


The femtosecond pump and probe technique with 2eV and 4eV photons was applied to the study of hot photocarriers with considerable excess energy in extended states of a-Si:H and a-Ge:H. Photoinduced changes in the complex dielectric constant ε1 + iε2 were calculated from the measured changes in reflectivity ΔR and transmission ΔT. This technique enables us to estimate that the average carrier cooling rates in our a-Si:H and a-Ge:H samples are about 2eV/psec and 1eV/psec, respectively. Photoinduced bleaching associated with the filling of band states dominates over intraband contributions to Δε1 and Δε2 for photon energies significantly exceeding the bandgap.

Original languageEnglish (US)
Pages (from-to)531-534
Number of pages4
JournalJournal of Non-Crystalline Solids
Issue numberPART 1
StatePublished - 1991


ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Materials Chemistry

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