Bubbles defects distribution in sapphire bulk crystals grown by Czochralski technique

Sapphire crystals exhibit microscopic defects known as micro-bubbles or micro-voids. We have studied micro-bubbles distribution, and their sizes in sapphire crystals grown by Czochralski technique. They are not uniform, depend on the pulling rate and their presence strongly affect the optical properties such as transmission and wavefront quality. The results provide important information about micro-bubbles distribution and the possibilities to minimize their propagation during the growth procedure of sapphire single crystal using Czochralski technique. (C) 2012 Elsevier B.V. All rights reserved.