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Proceedings Paper

Subpicosecond time-resolved terahertz time-domain spectroscopy of transient carrier dynamics in semiconductors
Author(s): Michael Schall; Markus Walther; Carsten Winnewisser; Hanspeter Helm; Peter Uhd Jepsen
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Paper Abstract

We have applied a newly developed transient terahertz time- domain spectrometer to study the temporal development of the dynamics of photogenerated carriers in semiconductor materials. The study presented here include semi-insulating (SI) and low-temperature-grown (LT) GaAs. By measuring the detailed shape of a subpicosecond electrical field pulse (THz pulse) transmitted through the sample at a time T after excitation with a femtosecond laser pulse, the absorption coefficient and refractive index in the region between 0.1 THz and 3 THz can be measured with high accuracy. By varying the time T, the transient absorption and index spectra can be measured with subpicosecond time resolution. Temporal and spectral behavior of the carrier dynamics in SI and LT GaAs, in dependence of intensity and wavelength of the excitation pulse, is measured. We directly observe carrier scattering to the sidevalleys and the subsequent return of the carriers to the central valley. The experimental data strongly suggest that the transmission of the THz pulse through the photoconducting surface layer of the semiconductor can be described as instantaneous tunneling of the electric field through a metal-like barrier.

Paper Details

Date Published: 9 September 1999
PDF: 8 pages
Proc. SPIE 3828, Terahertz Spectroscopy and Applications II, (9 September 1999); doi: 10.1117/12.361038
Show Author Affiliations
Michael Schall, Univ. of Freiburg (Germany)
Markus Walther, Univ. of Freiburg (Germany)
Carsten Winnewisser, Univ. of Freiburg (Germany)
Hanspeter Helm, Univ. of Freiburg (Germany)
Peter Uhd Jepsen, Univ. of Freiburg (Germany)

Published in SPIE Proceedings Vol. 3828:
Terahertz Spectroscopy and Applications II
J. Martyn Chamberlain, Editor(s)

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