STOICHIOMETRIC LINBO3 SINGLE-CRYSTAL GROWTH BY DOUBLE CRUCIBLE CZOCHRALSKI METHOD USING AUTOMATIC POWDER SUPPLY-SYSTEM

Stoichiometric LiNbO3 single crystals 40 mm in diameter and 50-100 mm in length were grown by the Czochralski method using a double crucible and automatic powder supply system. The crystals were grown from a Li-rich melt (Li2O 58-60 mol%) in the inner crucible, and the stoichiometric LiNbO3 powder was supplied smoothly and continuously to the outer melt. From the lattice parameter and Curie temperature measurements, the chemical composition through the grown crystal was found to be close to the stoichiometric composition. The as-grown crystals were of single domain except at the periphery. From a comparison of the transmittance between stoichiometric and congruent LiNbO3 single crystals, the absorption edge wavelength of the stoichiometric crystal was found to be 10 nm shorter than the congruent crystal. From these results, it is expected that this double crucible Czochralski method can be effectively applied to control crystal stoichiometry during growth and to produce uniformly doped single crystals of various oxide compositions.