Observation of nonequilibrium carrier distribution in Ge, Si, and GaAs by terahertz pump-terahertz probe measurements

János Hebling, Matthias C. Hoffmann, Harold Y. Hwang, Ka Lo Yeh, Keith A. Nelson

Research output: Contribution to journalArticle

106 Citations (Scopus)

Abstract

We compare the observed strong saturation of the free-carrier absorption in n -type semiconductors at 300 K in the terahertz (THz) frequency range when single-cycle pulses with intensities up to 150 MW/ cm2 are used. In the case of germanium, a small increase in the absorption occurs at intermediate THz pulse energies. The recovery of the free-carrier absorption was monitored by time-resolved THz pump-THz probe measurements. At short probe delay times, the frequency response of germanium cannot be fitted by the Drude model. We attribute these unique phenomena of Ge to dynamical overpopulation of the high mobility Γ conduction-band valley.

Original languageEnglish
Article number035201
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume81
Issue number3
DOIs
Publication statusPublished - Jan 4 2010

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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