Acoustoelastic Effect in Stressed Anisotropic Plates

This paper presents a forward calculation and analytic results of plate wave propagation in stressed plates of cubic materials. The single crystalline Ge films deposited on the Z-cut silicon wafers are investigated. Significant biaxial residual stresses in the film results from the lattice misfit between of the Ge film and the Si substrate. Phase velocity change of the acoustic waves due to mechanical stresses of the media is known as acoustoelastic (AE) effect. The calculated results indicate that the single Ge film has significant AE effect on the Lamb waves because of residual stresses induced in fabrication. The variations of phase velocity change are as small as only several m/s for the Lamb waves and even higher-order modes propagating in the Ge/Si layered system. It is still a challenge to identify the residual stresses in a thin-film heterostructure system using the measured phase velocity data of Lamb waves.