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Proceedings Paper

Coherent dynamics of excitons in GaN studied by femtosecond four-wave-mixing spectroscopy
Author(s): Arthur J. Fischer; W. Shan; Jin-Joo Song; Dongsik Kim; DaeSu Yee; Yia-Chung Chang; Robert D. Horning; Barbara L. Goldenberg
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Paper Abstract

Femtosecond four-wave-mixing (FWM) is used to study the coherent dynamics of excitons in thin epilayers of GaN grown by metalorganic chemical vapor deposition on sapphire substrates. Temperature dependent FWM is used to accurately measure the exciton homogeneous linewidth and it is shown that the exciton-LO phonon interaction is larger in GaN than in other III-V materials. Furthermore, the excitonic resonances in our samples are shown to be very nearly homogeneously broadened even at low temperature. We have observed strong beating behavior in the FWM signal corresponding to the energy separation of the A and B free exciton transitions. The beats were studied as a function of relative position across the B exciton linewidth in order to determine that the beating is due to a coherent exchange of population between the A and B excitons and not to, so called, polarization interference. The quantum beats were further studied as a function of polarization geometry and a phase shift of 180 degrees was observed when changing from collinear to cross-linear polarization geometries. The FWM signal was calculated in the ultrashort pulse limit in order to theoretically model the observed phase change.

Paper Details

Date Published: 23 April 1998
PDF: 8 pages
Proc. SPIE 3277, Ultrafast Phenomena in Semiconductors II, (23 April 1998); doi: 10.1117/12.306141
Show Author Affiliations
Arthur J. Fischer, Oklahoma State Univ. (United States)
W. Shan, Oklahoma State Univ. (United States)
Jin-Joo Song, Oklahoma State Univ. (United States)
Dongsik Kim, Seoul National Univ. (South Korea)
DaeSu Yee, Seoul National Univ. (South Korea)
Yia-Chung Chang, Univ. of Illinois/Urbana-Champaign (United States)
Robert D. Horning, Honeywell Technology Ctr. (United States)
Barbara L. Goldenberg, Honeywell Technology Ctr. (United States)

Published in SPIE Proceedings Vol. 3277:
Ultrafast Phenomena in Semiconductors II
Kong-Thon F. Tsen; Harold R. Fetterman, Editor(s)

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