Exciton-acoustic-phonon scattering in (Zn,Cd)Se/ZnSe quantum wells-the influence of quantum confinement

To study the influence of quantum confinement on exciton-acoustic-phonon scattering, we have grown seven (Zn,Cd)Se/ZnSe samples by MBE onto GaAs substrates. Exciton-resonant, femtosecond time-integrated four-wave mixing (TI-FWM) was carried out on each sample at five temperatures between 4 and 70 K and five excitation densities. Acquisition of this large data set of 175 TI-FWM delay scans is made possible by the use of fast-scan time-delay techniques. Exponential fits to the data, assuming a photon-echo configuration, yield measured values of /spl gamma/ (homogeneous exciton linewidth). Linear fits to these /spl gamma/ values at low temperature (<50 K) for a given excitation density provide the exciton-acoustic-phonon scattering parameter, /spl alpha/, for a particular sample and confirmed /spl alpha/ to be independent of excitation density. We have observed that the maximum of both the exciton-acoustic-phonon scattering parameter and the exciton binding energy occur at a similar well width indicating that the exciton-acoustic-phonon scattering rate is also directly correlated to the degree of quantum confinement.