Abstract
Femtosecond degenerate four-wave-mixing (FWM) is used to study coherent dynamics of excitons in GaN epilayers. Spectrally resolved (SR) FWM data are dominated by the and intrinsic excitonic resonances. SR FWM combined with time-integrated (TI) FWM demonstrates that the excitonic resonances are nearly homogeneously broadened even at low temperature. The temperature-dependent dephasing rate is used to deduce exciton-phonon interaction rates. TI FWM shows a strong beating between the and excitons and the beats are shown to be true quantum beats. In addition, a phase shift in the quantum beating was observed when the polarization geometry was changed from collinear to cross linear.
- Received 10 December 1996
DOI:https://doi.org/10.1103/PhysRevB.56.1077
©1997 American Physical Society