We describe time-integrated and spectrally resolved degenerate four-wave mixing (DFWM) on hexagonal GaN on sapphire for different laser energies and intensities. Our measured DFWM signal decays exhibit no contributions originating from polariton propagation effects in the 1- to 3-(Formula presented)m-thick bulk samples or from exciton/free-carrier scattering. At low temperatures and low excitation intensities the dephasing time of the (Formula presented) exciton is as long as 3 ps and is most likely due to scattering by defects. At excitation densities above (Formula presented) exciton-exciton scattering becomes the dominant dephasing mechanism and a fifth-order diffraction signal is observed above (Formula presented).
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jan 1 1997|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics