Evolution of cristobalite clusters on silica glass surfaces in molten silicon

Crystal growth at the interface between silica glass and molten silicon was investigated to clarify the formation process of a ring structure at the s urface of Czochralski crucibles. A cluster of faceted cristobalite at the i nterface was found to grow laterally and then transform into a ring with di sappearance of the faceted crystals at the, central region. The production of the cristobalite cluster is explained by dissolution of silica glass int o molten silicon and deposition of crystalline cristobalite at a nucleation site. Redissolution of the crystal at the central area of the cluster resu lted in the formation of a ring structure. It is deduced that the nucleatio n site of cristobalite clusters is provided by the devitrification of silic a glass. (C) 2000 The Electrochemical Society. S0013-4651(98)11-099-6. All rights reserved.