Evolution of interface configuration in sapphire single crystal growth via Czochralski method

Abstract

The evolution of interface configuration during sapphire crystal growth by Czochralski method was studied on the basis of chemical bonding conditions at crystal/melt interface. On the basis of chemical bonding theory of single crystal growth, when sapphire single crystal was grown along the c axis direction in Czochralski system, crystal/metal interface is composed of six crystallographically equivalent {110} interfaces thermodynamically. With the rotation of sapphire single crystal in the growth process, the interface configuration developed from hexagon to circle due to the appearance of {100} surfaces and {h10} microfacets at the intersection of two adjacent interfaces. The (h10) microfacet is made of (100) and (110) planes. Lower chemical bonding densities at the {100} surfaces and {h10} microfacets relative to that at {110} surfaces thermodynamically drive the formation of round interface configuration in sapphire Czochralski crystal growth along the c axis direction.

Keywords:

• Sapphire
• Interface configuration
• Chemical bonding theory
• Bonding density
• Czochralski method

Financial supports from the National Natural Science Foundation of China (grant nos. 51125009, 50872016 and 20973033), National Natural Science Foundation for Creative Research Group (grant nos. 20921002 and 21221061) and Hundred Talents Program of Chinese Academy of Sciences are acknowledged.