Acoustoelastic anomaly in stressed heterostructures - art. no. 113308

We investigated the influence of stress an the,acoustic wave propagation in single crystalline heterostructures using a transfer matrix method. Both R ayleigh-type and Sezawa modes exhibit an acoustoelastic anomaly, where the stress-induced change of the phase velocity is maximum for finite film thic knesses, considerably smaller than the acoustic wavelength. For Ge/Si(001) compressed by I GPa the velocity shift of Sezawa modes reaches exceptionall y high values of about 2%. These results demonstrate the importance of stre ss effects on the determination of elastic constants of thin film heterostr uctures.