Industrial growth of lithium tetraborate (Li/sub 2/B/sub 4/O/sub 7/) piezocrystal and its SAW applications

Lithium tetraborate Li/sub 2/B/sub 4/O/sub 7/ (LBO) single crystal is a superior substrate material for surface acoustic wave and bulk acoustic wave devices due to its fairly high electromechanical coupling factor and zero temperature coefficient of frequency in [110] plane. In this paper, Bridgman growth of large size LBO crystals is presented from an industrial point of view. The improvements and advantages of the modified Bridgman method are discussed. Mass production of /spl Phi/3 4 LBO boules has been realized in our laboratory. The fabrication of SAW devices based on LBO wafers is introduced briefly.