Reduction of electron-optical phonon scattering rates in a quantum well with a phonon wall

The intrasubband electron-polar optical phonon scattering rates for interface and confined phonons are calculated. The AlAs/GaAs/AlAs double heterostructures with independent confinement of electrons and phonons as well as structures containing a phonon wall (a phonon-reflecting barrier transparent to electrons) embedded in an electron quantum well (QW) are considered. It is shown that, because of the independent electron and phonon confinement in the double heterostructure, the scattering rate is lower than that obtained in the case of electron confinement alone. The total scattering rate by confined and interface phonons in the QW with a phonon wall is reduced significantly as compared with the rate of confined electron scattering by bulk phonons. Thus, the phonon wall within the electron QW is a powerful means of reducing electron scattering and enhancing, correspondingly, the electron mobility in two-dimensional (2D) heterostructures.