Acoustoelastic effect in stressed heterostructures

摘要

Mechanical stresses influence the phase velocity of acousticnwaves, known as the AE (acoustoelastic) effect. In order to calculatenthe AE effect of biaxially stressed layered systems, we extended thentransfer matrix method for acoustic wave propagation by considering thenchange of the density, the influence of residual stress, and thenmodification of the elastic stiffness tensor by residual strain and bynthird-order constants. The generalized method is applied to thencalculation of the angular dispersion of the AE effect for transversenbulk modes and surface acoustic waves on Ge(001). Our calculationsnreveal that the AE effect significantly depends on the propagationndirection and can even change sign. The maximal velocity change occursnfor transversally polarized waves propagating parallel to the [110]ndirection. For the layered Ge/Si(001) system, the AE effect isninvestigated for Love modes propagating in the [100] and [110]ndirections. The AE effect increases rapidly with increasing layernthickness and almost reaches its maximal value when the wave stillnpenetrates into the unstressed substrate