Surface and pseudo-surface acoustic waves piezoelectrically excited in diamond-based structures

Surface and pseudo-surface acoustic plane waves generated in two- and three-layer AlN/Diamond and AlN/Diamond/γ-TiAl structures by a point electric source are analyzed in the mathematical framework based on the Green's matrix integral representation and guided wave asymptotics derived using the residue technique. The attention is focused on the effect of pseudo-surface-to-surface wave degeneration at certain discrete values of h/λ (h is the thickness of the piezoelectric layer and λ is the wave-length). Earlier such optimal ratios were discovered and experimentally verified for the first pseudo-surface (Sezawa) wave mode in the AlN/Diamond structure. The present research reveals this effect for higher modes as well as examines its manifestation for three-layer structures with different diamond-to-AlN thickness ratios H/h.