Paper
23 April 1998 Coherent dynamics of excitons in GaN studied by femtosecond four-wave-mixing spectroscopy
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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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.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Arthur J. Fischer, W. Shan, Jin-Joo Song, Dongsik Kim, DaeSu Yee, Yia-Chung Chang, Robert D. Horning, and Barbara L. Goldenberg "Coherent dynamics of excitons in GaN studied by femtosecond four-wave-mixing spectroscopy", Proc. SPIE 3277, Ultrafast Phenomena in Semiconductors II, (23 April 1998); https://doi.org/10.1117/12.306141
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KEYWORDS
Excitons

Gallium nitride

Polarization

Femtosecond phenomena

Phase shifts

Spectroscopy

Gallium arsenide

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