ELECTRON-MOBILITY AND SUBBAND POPULATION TUNING BY A PHONON WALL INSERTED IN A SEMICONDUCTOR QUANTUM-WELL

The electron-optical phonon scattering rate and electron subband popul ation in a semiconductor quantum well (QW) containing a phonon wall (P h-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 radica lly the intra- and intersubband scattering rates. Electron subband ene rgy spectra, phonon frequencies, electron and phonon wave functions an d scattering rates are found to depend on the Ph-wall position in the QW. The largest decrease of the intrasubband electron-phonon scatterin g rate takes place when the Ph-wall is located at the QW center. The i ntersubband scattering rate increases resonantly when the intersubband energy separation is equal to the interface phonon energy. The Ph-wal l increases the electron mobility in the QW except the areas where the resonance scattering takes place. The Ph-wall position in the QW caus ing the subband population inversion is determined in the case of opti cal excitation. (C) 1997 American Institute of Physics.