Theoretical investigation of the lattice dynamics of GaAlSb superlattices

We investigate from first principles the effect of substitutional disorder on the off-resonance Raman activity of GaSb/AlSb superlattices (SLs) includ ing strain and mixing effects. The method we use is based on a perturbation scheme which allows to take into account both the actual chemical configur ation and local displacements from a given reference (virtual) system. We c alculate the first-order Raman spectra of different (GaSb)(n)(AlSb)(n) supe rlattices grow:n in the [0 0 1] direction. The investigation of the effects of the interface modes on the Raman spectra allows the correct interpretat ion of the features found in the experiment. (C) 2001 Elsevier Science B.V. All rights reserved.