Confined and interface phonon scattering in finite barrier GaAs/AlGaAs quantum wires

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Abstract
We report on the calculation of the total scattering rate in finite barrier GaAs/AlGaAs quantum wires based on the interaction Hamiltonian of confined longitudinal optical (LO) phonon and surface (SO) phonon modes. With multisubband processes being properly taken into account, our calculation indicates that for GaAs type of phonons the high-frequency symmetric (s+) branch plays an important role among all the other SO phonon branches; it can even dominate over confined LO phonons in highly confined quantum wires as observed by K. W. Kim, M. A. Stroscio, A. Bhatt, R. Mickevicius, and V. V. Mitin [J. Appl. Phys. 70, 319 (1991)]. Our results also demonstrate that the total contributions of confined LO and SO phonon scattering resemble closely to GaAs bulk LO phonon scattering. Selection rules between intersubband transitions for SO modes suggest the possibility of a bottle-neck effect for carrier relaxation in square wires compared with rectangular wires.