Subpicosecond time-resolved terahertz time-domain spectroscopy of transient carrier dynamics in semiconductors

M. Schall, M. Walther, C. Winnewisser, H. Helm, Peter Uhd Jepsen, J. M. Chamberlain (Editor)

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearch

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 semiinsulating (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 behaviour 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.
Original languageEnglish
Title of host publicationTERAHERTZ SPECTROSCOPY AND APPLICATIONS 11
Number of pages8
PublisherSpie-int Soc Optical Engineering
Publication date1999
Pages220-227
ISBN (Print)0-8194-3314-4
DOIs
Publication statusPublished - 1999
Externally publishedYes
EventConference on Terahertz Spectroscopy and Applications II - Munich, Germany
Duration: 16 Jun 199918 Jun 1999

Conference

ConferenceConference on Terahertz Spectroscopy and Applications II
CountryGermany
CityMunich
Period16/06/199918/06/1999
SeriesProceedings of SPIE, the International Society for Optical Engineering
Volume3828
ISSN0277-786X

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