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Proceedings Paper

Ultrafast carrier dynamics in GaN epilayers studied by femtosecond pump-probe spectroscopy
Author(s): Arthur J. Fischer; Brian D. Little; Theodore J. Schmidt; Chan-Kyung Choi; Jin-Joo Song; Robert D. Horning; Barbara L. Goldenberg
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Paper Abstract

Femtosecond pump-probe measurements were performed in GaN epilayers to study carrier dynamics in the band edge region. Excitonic absorption was found to begin saturating at a pump fluence of 20 (mu) J/cm2 which corresponds to an estimated carrier density of 1 X 1018 cm-3. At zero delay between pump and probe, induced absorption is observed below the unpumped band gap due to ultrafast bandgap renormalization. After 375 fs, a large induced transparency is observed just below the excitonic resonance which is due to a transient electron-hole plasma. After 1 ps, the absorption has partially recovered to a level associated with excitonic phase-space filling. The absorption then recovers with a characteristic time of approximately 20 ps, a value which increases with increasing excitation density.

Paper Details

Date Published: 24 May 1999
PDF: 9 pages
Proc. SPIE 3624, Ultrafast Phenomena in Semiconductors III, (24 May 1999); doi: 10.1117/12.349293
Show Author Affiliations
Arthur J. Fischer, Oklahoma State Univ. (United States)
Brian D. Little, Oklahoma State Univ. (United States)
Theodore J. Schmidt, Oklahoma State Univ. (United States)
Chan-Kyung Choi, Oklahoma State Univ. (United States)
Jin-Joo Song, Oklahoma State Univ. (United States)
Robert D. Horning, Honeywell Technology Ctr. (United States)
Barbara L. Goldenberg, Honeywell Technology Ctr. (United States)

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

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