Acoustic properties of anistropic substrates

Nano-and micro-structures for telecommunications and sensing applications will, in the near and farther future, continue to become increasingly more intricate. They will operate at higher frequencies, and will incorporate various processing and actuation modalities in novel and very compact architectures. One of these modalities is anisotropic acoustics. Today, the great majority of acoustic devices are not part of an integrated structure, and operate using a single type of motion; current thin-film resonators (TFRs) and stacked-crystal filters (SCFs) are examples. To facilitate the realization of more sophisticated integrated structures, in this paper are given the relevant bulk acoustic wave parameters and values for a variety of anisotropic materials considered most likely to play important parts as multi-mode substrates and/or as active layers. The materials fall into the cubic (e.g., Si, Ge, C(d), and GaAs), hexagonal (e.g., the new single-crystal ferroelectrics), and trigonal (e.g., sapphire, lithium niobate, lithium tantalate, langasite and its isomorphs) crystal classes.