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Proceedings Paper

Terahertz emission spectroscopy of coherent phonons in semiconductors
Author(s): Masahiko Tani; Ryoichi Fukasawa; Michael Herrmann; Kiyomi Sakai; Shin-ichi Nakashima; Nobuya Yoshioka; Akihiro Ishida; Hiroshi Fujiyasu
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Paper Abstract

We investigate infrared-active coherent phonons excited in Te, PbTe (un-doped, n-type and p-type), and CdTe by observing the terahertz (THz) emission from these samples. Coherent THz emission corresponding to the longitudinal- optical (LO)-phonon frequency has been observed for all the samples, while no significant THz emission is observed at the transverse-optical (TO)-phonon frequency even at high carrier densities (> 1018 cm-3). The absence of THz emission at the TO-phonon frequency strongly contradicts the observation in the transient reflectivity measurements, where the signal oscillations at the TO-phonon frequencies arising from the LO-phonon-plasmon coupling (L_ mode) have been observed at high carrier densities. It is found from a model calculation that for a dipole oscillator on a sample surface the THz emission around the TO-phonon frequency is strongly suppressed due to the large dielectric constant near this frequency.

Paper Details

Date Published: 24 May 1999
PDF: 10 pages
Proc. SPIE 3624, Ultrafast Phenomena in Semiconductors III, (24 May 1999); doi: 10.1117/12.349285
Show Author Affiliations
Masahiko Tani, Communications Research Lab. (Japan)
Ryoichi Fukasawa, Communications Research Lab. (Japan)
Michael Herrmann, Communications Research Lab. (Japan)
Kiyomi Sakai, Communications Research Lab. (Japan)
Shin-ichi Nakashima, Osaka Univ. (Japan)
Nobuya Yoshioka, Shizuoka Univ. (Japan)
Akihiro Ishida, Shizuoka Univ. (Japan)
Hiroshi Fujiyasu, Shizuoka Univ. (Japan)

Published in SPIE Proceedings Vol. 3624:
Ultrafast Phenomena in Semiconductors III
Kong-Thon F. Tsen, Editor(s)

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