METHOD FOR GROWING LITHIUM NIOBATE SINGLE CRYSTAL

• Main Author: KAJIGAYA TOMIO
• Format: Patent
• Language: English; Japanese
• Published: 17.09.2020
• Subjects: AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUSPOLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR; CHEMISTRY; CRYSTAL GROWTH; METALLURGY; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE; REFINING BY ZONE-MELTING OF MATERIAL; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITHDEFINED STRUCTURE; SINGLE-CRYSTAL-GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL ORUNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL

To provide a method for stably growing a high quality lithium niobate (LN) single crystal by the Czochralski method even when growing a large-sized crystal having a diameter of 4 inches or more.SOLUTION: A method for growing a LN single crystal by the Czochralski method, capable of contacting a seed crystal 1 to a raw material melt in a crucible 12 arranged in the chamber 11 of a single crystal growth apparatus 10 and pulling the seed crystal by a pulling shaft (a seed rod) 16 while rotating the seed crystal to grow a crystal shoulder part and a crystal straight body part followed thereby comprises: controlling a temperature atmosphere in a space above the crucible so that the average temperature gradient on the pulling shaft 16 from a position above 1 mm from the surface of the raw material melt to a position above 20 mm is 2-10°C/cm; and contacting the seed crystal to the raw material melt to grow a lithium niobate single crystal having 4 inches or more of the crystal diameter of the crystal straight body part.SELECTED DRAWING: Figure 1 【課題】直径４インチ以上の大型結晶を育成する場合でも、安定的に高品質のニオブ酸リチウム（ＬＮ）単結晶をチョコラルスキー法により育成する方法を提供すること。【解決手段】単結晶育成装置10のチャンバー11内に配置された坩堝12の原料融液に種結晶１を接触させ、種結晶を回転させながら引上げ軸（シード棒）16により引上げて結晶肩部とこれに続く結晶直胴部を育成するチョコラルスキー法によるＬＮ単結晶の育成方法であって、原料融液表面より１ｍｍ上方の位置から２０ｍｍ上方の位置までの引上げ軸16上の平均温度勾配が２℃／ｃｍ〜１０℃／ｃｍとなるように坩堝上方空間の温度雰囲気を調整した後、種結晶を原料融液に接触させて結晶直胴部の結晶径が４インチ以上のニオブ酸リチウム単結晶を育成することを特徴とする。【選択図】図１