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Proceedings Paper

Ultrafast carrier dynamics in semiconductor superlattices: terahertz gain and dephasing mechanism (Invited Paper)
Author(s): Norihiko Sekine; Yozo Shimada; Kazuhiko Hirakawa
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Paper Abstract

We have directly determined the spectral shape of the complex conductivities of Bloch oscillating electrons by using time-domain terahertz (THz)-electrooptic sampling technique and presented an experimental evidence for a dispersive Bloch gain in superlattices. This unique dispersive gain without population inversion arises from a non-classical nature of Bloch oscillations; that is, the phase of the Bloch oscillation (BO) is shifted by π/2 from that of the semi-classical charged harmonic oscillation when driven by the same ac field. By increasing the bias electric field, the gain bandwidth reached ~3 THz in our particular sample. It was also found that the dominant dephasing mechanism of the BOs is identified to be the interface roughness scattering (alloy disorder scattering) below (above) the critical bias electric field.

Paper Details

Date Published: 13 April 2005
PDF: 8 pages
Proc. SPIE 5725, Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX, (13 April 2005); doi: 10.1117/12.607517
Show Author Affiliations
Norihiko Sekine, Univ. of Tokyo (Japan)
Yozo Shimada, National Institute of Advanced Industrial Science and Technology (Japan)
Kazuhiko Hirakawa, Univ. of Tokyo (Japan)


Published in SPIE Proceedings Vol. 5725:
Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX
Kong-Thon Tsen; Jin-Joo Song; Hongxing Jiang, Editor(s)

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