Growth of 3-inch langasite single crystal and its application to substratefor surface acoustic wave filters

Macro defect-free langasite (La3Ga5SiO14) of 3" diameter was grown by the C zochralski technique. Thermal treatment of the melt and a uniform interface shape are important for langasite growth with a clear habit of faceting. T he homogeneity in composition was two-dimensionally investigated by X-ray d iffraction analysis and SAW (surface acoustic wave) velocity distribution o n the wafer fabricated from the crystal. The deviation was sufficiently sma ll for the use of langasite as a suitable substrate in SAW device applicati ons. SAW properties were calculated based on the available material constan ts.