Elastic surface waves in crystals with overlayers: cubic symmetry

The elastic surface waves of systems formed by semi-infinite cubic crystals with overlayers of cubic symmetry, having (001) free surfaces and interfaces was studied using a Green's-function technique, for arbitrary thickness and direction of propagation. For the symmetry directions (100) and (110) in the limit of small thickness of the overlayers, it is possible to obtain the dispersion relation of Rayleigh and Love waves in closed form, to first order in h kappa (h is the thickness of the overlayer; kappa is the parallel wave vector). An application is made to the system formed by a layer of Ga sub x Al sub 1--x As on a GaAs substrate and the influence of the layer composition on the dispersion relation of the elastic surface waves is discussed. 31 ref.--AA