INTRINSIC DEPHASING TIMES OF PHOTOEXCITED ELECTRON VALENCE-HOLE PAIRSNEAR THE FERMI-EDGE OF A DEGENERATE ELECTRON-GAS IN QUANTUM-WELLS

Various single-particle and collective-mode scattering processes that contribute to the intrinsic dephasing time of photoexcited electron-va lence-hole pairs in degenerate, modulation-doped quantum wells are dis cussed. Detailed calculations show that sharp discontinuities in the e nergy dependence of the electron dephasing time can give information a bout short-range correlations associated with large wave vectors and h igh-frequency excitations of the coupled electron-LO-phonon system. Ho wever, to extract dephasing times from coherent optical excitations th e effects of the complex valence-band structure; i.e., mixing of light and heavy holes in GaAs quantum wells, must be considered.