4 inch langasite crystals grown along SAW-cut orientations

• LGS crystals were possible to saw 4 in. wafer which was grown along the SAW-cut orientations.
• The ratio of crystal diameter and crucible diameter must be less than 60%.
• The rotation rate should be adapted during growth.
• The growth rate must be below the critical growth rate.
• The average frequency constant value is 1.34 MHz mm.

Langasite crystal is an important substrate material for intermediate frequency surface acoustic (IF-SAW) wave filters and high temperature sensors, due to their high piezoelectric constants, electromechanical coupling factor and no phase transformation up to the melting point. In this work, 3 and 4 in. circular shaped langasite crystals along SAW-cut orientations (0°, 22°, 90°) and (0°, 138.5°, 26.6°) were grown successfully. Key parameters to grow high quality crystals are discussed. Rocking curve and frequency tests show a high homogeneity of these crystals. Homogeneous langasite crystals grown along a SAW-cut orientation with controlled shape are of enormous commercial value.