Czochralski crystal growth and characterization of large langatate (La3Ga5.5Ta0.5O14, LGT) crystals for SAW applications
Résumé
1.5 and 2 inch LGT, langatate (La$_3$Ga$_{5.5}$Ta$_{0.5}$O$_{14}$) crystals along the X[100], Y[120] and Z[001]-directions were successfully grown by the Czochralski technique under an argon/O$_2$ (0.1–0.5%) atmosphere. Homogeneous and defect-free crystals were obtained in a stationary stable regime. The ingot faceting is discussed as a function of growth direction. The interface shape is investigated as a function of the rotation rate. It is observed that crystal coloration depends on the growth atmosphere. Ga$_2$O$_3$ dendritic deposition on the crystal surface causes damage. It is shown that additional oxygen gas in the growth chamber limits melt decomposition and prevents the occurrence of dendrites. Surface acoustic wave (SAW) resonators are produced from the LGT grown crystals.