ELECTRON-PHONON INTERACTION AND LOW-FIELD DRIFT MOBILITY IN A POLAR SEMICONDUCTOR QUANTUM-WELL

We have calculated relaxation times by means of a general iterative pr ocedure when the electron-phonon interaction is included via three sca ttering mechanisms: the acoustic deformation potential, the piezoelect ric of the acoustic branch, and longitudinal optical mode coupling (LO ). Confinement of LO vibrations is taken into account by means of an a ppropriate Hamiltonian, and this leads to some selection rules for thi s interaction, which are carefully discussed. Screening of the electro n-phonon interaction is considered. Mobility calculations are carried out in a size-quantum-limit (SQL) approximation. We have compared the effects on the screening contributions of the different scattering mec hanisms and the confinement effects, produced by the use of different approximations for the electronic part, ranging from a self-consistent solution to an infinite barrier model.