ELASTIC-CONSTANTS AND SURFACE ACOUSTIC-WAVES OF SUPERLATTICES

Elastic constants of superlattices and their surface acoustic waves ar e theoretically studied. An exact expression to calculate the surface acoustic wave velocity dispersions is derived for superlattices of fin ite thickness consisting of two kinds of layers rigidly stacked upon e ach other. The formulations are performed for both free superlattice p lates and substrated superlattices. Numerical calculations for Cu/Al a nd Cu/Ag systems are compared with those obtained using the effective elastic constant (EEC) model (Grimsditch M 1985 Phys. Rev. B 31 6818). A comparison clarifies the applicability of the EEC model.