Localized interface optical-phonon modes in superlattices with structural defects

摘要

Within the framework of dielectric continuum theory, we investigate the property of the localized interface optical-phonon modes (IOPM's) in semiconductor superlattices (SL's) with a structural defect layer. We find that for certain structural parameters the localized IOPM's always appear in pairs inside each frequency gap. Moreover, they possess either symmetric or antisymmetric properties with respect to the center of the defect layer and correspond to longitudinal and transverse vibrations, respectively. The frequency and the localization degree of these localized modes sensitively depend on the relative widths of the constituent layers in the unit cell and of the defect layer, and on the direction of propagation, but they are not affected by the period of the superlattice. [References: 24]