貴金属坩堝を使わずコールドクルーシブルを用いた酸化物バルク単結晶作製法

抄録

  The most of the oxide single crystals used as industrial products such as LiTaO₃ (LT), LiNbO₃ (LN), sapphire, Y₃Al₅O₁₂ (YAG), Gd₃(Al,Ga)₅O₁₂ (GAGG), etc. are produced by the Czochralski (CZ) method. In the CZ method, crucibles are regarded as indispensable for holding the melt. Especially in the case of oxides, crucibles are often used as a heat source, as well. However, the use of crucibles has long been a problem due to the following reasons: (1) crucibles limit the melting points of materials that can be handled and the atmosphere in which they can be grown, (2) crucibles are a source of impurities and other defects, and (3) crucibles are expensive (precious metals are used for growing materials with high melting points). In this paper, the Skull melt method, a melt growth method that does not use a crucible, is introduced. Oxide Crystal growth from Cold Crucible (OCCC) method, a fusion of the CZ method and Skull melt methods, was also introduced. In this report, the results of melt growth of GAGG and gallium oxide grown by the OCCC method are demonstrated. The fact that bulk single crystals of gallium oxide with a diagonal length of nearly 50 mm were obtained gives hope for the possibility of this method as a mass production technology.