Femtosecond Exciton Dynamics and the Mott Transition in GaN under Resonant Excitation
✍ Scribed by S. Hess; R.A. Taylor; K. Kyhm; J.F. Ryan; B. Beaumont; P. Gibart
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 174 KB
- Volume
- 216
- Category
- Article
- ISSN
- 0370-1972
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✦ Synopsis
We present resonant femtosecond pump±probe reflectance measurements of excitons in high quality wurtzite GaN epilayers for a range of lattice temperatures and various pump intensities. From the density dependence of the excitonic bleaching we find that the Mott density is n Mott 2X2 Â 10 19 cm À3 . At 4 K we find that the exciton dynamics is dominated by trapping at defects via acoustic phonon emission on a timescale of $16 ps. At temperatures above 60 K we observe a much longer relaxation component of $350 to 400 ps, which we ascribe to the radiative recombination of free excitons.