Single crystal growth mechanism of sapphire

Abstract

We studied the single crystal growth mechanism of sapphire on the basis of chemical bonding calculations at growth interface and the growth of bulk crystal by Czochralski method. The high dislocation density of sapphire single crystals originated from octahedral linking of AlO6 octahedra via sharing their common plane in the structure, which results in intrinsic defects in sapphire single crystals. On the basis of chemical bonding theory of single crystal growth, crystal morphology of sapphire was quantitatively calculated by the chemical bonding conditions of different crystal surfaces. Thermodynamically, sapphire single crystal preferred to exhibit rhombohedral polyhedron bounded by six crystallographically equivalent {012} planes. Bulk sapphire single crystal with the size of 55 mm in diameter and 210 mm in length was grown along the c-axis direction via Czochralski method.