TRANSITION FROM LO-PHONON TO SO-PHONON SCATTERING IN MESOSCALE STRUCTURES

Macroscopic dielectric continuum models of optical-phonon modes predic t enhancements in the magnitudes of the surface-optical (SO) modes in double-barrier heterostructures as the heterojunction-to-heterojunctio n separation is reduced. In this paper, the ratio of electron scatteri ng by the SO-phonon modes to that by the (electrostatic) confined long itudinal-optical- (LO-) phonon modes is calculated for a GaAs/AlAs sho rt-period superlattice based on the assumption that electron-SO-phonon scattering may be described by a scalar potential. The scaling of the ratio of electron-SO-phonon scattering to electron-LO-phonon scatteri ng as a function of the superlattice period provides a sensitive test of the appropriateness of the scalar-potential model. The effect of ph onon confinement on electron-optical-phonon scattering rates is presen ted for rectangular quantum wires as well. A major conclusion of these new results is that it is essential to model phonon confinement prope rly in predicting carrier transport properties in mesoscale structures .