Intrinsic dephasing times of photoexcited electron–valence-hole pairs near 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–valence-hole pairs in degenerate, modulation-doped quantum wells are discussed. Detailed calculations show that sharp discontinuities in the energy dependence of the electron dephasing time can give information about short-range correlations associated with large wave vectors and high-frequency excitations of the coupled electron–LO-phonon system. However, to extract dephasing times from coherent optical excitations the effects of the complex valence-band structure, i.e., mixing of light and heavy holes in GaAs quantum wells, must be considered.