Effect of interface disorder on the confined phonon modes of GaAs/AlAs superlattices

Abstract
We study the longitudinal optical-phonon modes in GaAs/AlAs(001) superlattices with disordered interface, using an 11-parameter rigid-ion model and the coherent-potential approximation. We show that, due to interface disorder, the frequencies of the confined modes deviate substantially from the bulk dispersion curve, the zone-center optical anisotropy is reduced, and the electrostatic interface modes show in the Raman spectrum. Our results are in good agreement with existing Raman measurements.