Theory for Optical-Phonon Raman Spectra of Imperfect Quantum Wells

A model, combining the effect of the matrix element of the Fröhlich interaction with the effect of the density of states of phonons, is proposed to clarify the origin of the Raman scattering lineshape in GaAs/AlAs multiple quantum wells(MQW), which has recently been assigned to the dips due to anticrossing of interface modes with the odd-order confined modes, rather than the peaks associated with the even-order modes. The numerical results based on this model have well reproduced main features in the resonant Raman scattering spectra of MQW with identical well width but different barrier widths and indicate that, when there exists the interface imperfection, the first several peaks in Raman spectra still result from the even-order confined modes, instead of the dips.