Novel composite piezoelectric materials using direct bonding techniques

Novel composite piezoelectric materials for new piezoelectric devices are reported. The fabrication process using direct bonding techniques, bonded interface microstructures, and usefulness for piezoelectric devices are also reported. Monocrystalline piezoelectric materials such as LiNbO/sub 3/ and LiTaO/sub 3/ were successfully bonded directly onto the same material or different materials including semiconductor, without using any adhesive or such, effecting physically and electro-acoustically optically satisfactory interfaces. Despite the relatively low temperature of the heat treatment, the interface was found uniform, virtually void-free, and to be accomplished in an atomic order by TEM observation. Applications to one-chip electro-acoustic ICs and optical guided wave devices are described.