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Summary: Measurements of the Carrier Dynamics
and Terahertz Response of Oriented
Germanium Nanowires using
Optical-Pump Terahertz-Probe
Spectroscopy
Jared H. Strait,*,
Paul A. George,
Mark Levendorf,
Martin Blood-Forsythe,
Farhan Rana,
and Jiwoong Park
School of Electrical and Computer Engineering, Department of Chemistry and
Chemical Biology, Cornell UniVersity, Ithaca, NY
Received April 30, 2009; Revised Manuscript Received June 22, 2009
ABSTRACT
We have measured the terahertz response of oriented Germanium nanowires using ultrafast optical-pump terahertz-probe spectroscopy. We
present results on the time, frequency, and polarization dependence of the terahertz response. Our results indicate intraband energy relaxation
times of photoexcited carriers in the 1.5-2.0 ps range, carrier density dependent interband electron-hole recombination times in the 75-125
ps range, and carrier momentum scattering rates in the 60-90 fs range. Additionally, the terahertz response of the nanowires is strongly
polarization dependent despite the subwavelength dimensions of the nanowires. The differential terahertz transmission is found to be large
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