EFG GROWTH OF SAPPHIRE TUBES UP TO 85 MM IN DIAMETER

Conditions for large tubular sapphire crystal growth have been examine d. Single crystalline tubes with outer diameters of upto 85 mm were gr own successfully by the EFG technique using a simple one-healer growth assembly. The dependence of structural perfection on growth condition s and die-top design have been investigated. The process for seed enla rgement upto the full-circular cross-section was found to be of primar y importance for high-quality growth, and a suitable algorithm has bee n suggested. (C) 1998 Elsevier Science B.V. All rights reserved.