The electron-optical phonon scattering rate and electron subband population in a semiconductor quantum well (QW) containing a phonon wall (Ph-wall) is calculated. It is shown that the Ph-wall (a barrier of one–two AlAs monolayers) inserted into an AlAs/GaAs/AlAs QW changes radically the intra- and intersubband scattering rates. Electron subband energy spectra, phonon frequencies, electron and phonon wave functions and scattering rates are found to depend on the Ph-wall position in the QW. The largest decrease of the intrasubband electron-phonon scattering rate takes place when the Ph-wall is located at the QW center. The intersubband scattering rate increases resonantly when the intersubband energy separation is equal to the interface phonon energy. The Ph-wall increases the electron mobility in the QW except the areas where the resonance scattering takes place. The Ph-wall position in the QW causing the subband population inversion is determined in the case of optical excitation. ©1997 American Institute of Physics.