On the existence of surface acoustic waves on piezoelectric substrates

The existence of surface waves on anisotropic materials was proven under fa irly general conditions by Lothe and Barnett in 1976 [1]. But, until now, t he status of surface waves on piezoelectric materials has remained unresolv ed. This paper presents general existence theorems for surface waves on pie zoelectric substrates. It is demonstrated that for short circuit boundary c onditions a surface wave solution must exist under virtually any circumstan ces. However, for a free surface, comparatively stringent existence conditi ons are required. Numerical examples are given for both free and shorted su rfaces, and it is demonstrated that, in some situations, a surface wave sol ution may not exist for free surface propagation. The existence proofs were developed as a result of theoretical work on Gree n function modeling, which is now the preferred technique for rigorous SAW and pseudo-SAW device analysis. The mechanisms of the existence proofs and the associated mathematical results give great insight into the structure a nd properties of the Green functions and include many results that are dire ctly relevant to device analysis.