Exceptionally slow rise in differential reflectivity spectra of excitons in GaN : effect of excitation-induced dephasing.
- University of Florida, Gainesville, FL
- Florida State University, Tallahassee, FL
- Seoul National University, Seoul, Korea
- Oklahoma State University, Stillwater, OK
Femtosecond differential reflectivity spectroscopy (DRS) and four-wave mixing (FWM) experiments were performed simultaneously to study the initial temporal dynamics of the exciton line-shapes in GaN epilayers. Beats between the A-B excitons were found only for positive time delay in both DRS and FWM experiments. The rise time at negative time delay for the DRS was much slower than the FWM signal or differential transmission spectroscopy at the exciton resonance. A numerical solution of a six band semiconductor Bloch equation model including nonlinearities at the Hartree-Fock level shows that this slow rise in the DRS results from excitation induced dephasing, that is, the strong density dependence of the dephasing time which changes with the laser excitation energy.
- Research Organization:
- Sandia National Laboratories
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 959242
- Report Number(s):
- SAND2004-2949J
- Journal Information:
- Proposed for publication in Physical Review B., Journal Name: Proposed for publication in Physical Review B.
- Country of Publication:
- United States
- Language:
- English
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