Importance of confined longitudinal optical phonons in intersubband and backward scattering in rectangular AlGaAs/GaAs quantum wires

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Abstract
The important role of confined longitudinal optical (LO) and surface optical (SO) phonons is investigated for different types of individual scattering processes in AlGaAs/GaAs quantum wires. Electron wave function tailing due to finite barrier height has been properly taken into account. We demonstrate that for highly confined wires structures Ly=Lz=40 Å, forward and backward scattering are dominated by SO phonons. For 80 Å×80 Å structures, forward scattering is still predominately by SO phonons while backward scattering is dominated by confined LO phonons. Finally, for 150 Å×150 Å, confined phonons control both forward and backward scattering. However, we demonstrate that confined LO phonons play a dominant role in intersubband transitions even in highly confined structures, and that it has the most significant effect on the backward scattering in quantum wires of Ly=Lz≳80 Å.