Atomic vibrations in thin [111] superlattices

Abstract

We present theoretical investigations of atomic vibrations in thin superlattices grown in the [111] direction with f.c.c. stacking, using the adiabatic bond-charge model. In the acoustic range we confirm the existence of guided Love modes. In the optical range we observe folding, confinement and mode anisotropy behaviours. We show that confined optical modes approximate travelling waves in the propagation layer, decaying rapidly outside. In addition we clearly show optical interface modes of both `AlAs' and `GaAs' type, and that these modes are of the `Fuchs-Kliewer' variety. We compare the results obtained for the [111] direction to previous results obtained for the [001] and [110] directions.