Brian G Demczyk

US Patent:

61430706, Nov 7, 2000

Filed:

May 15, 1998

Appl. No.:

9/093846

Inventors:

David F. Bliss - Arlington MA
Brian G. Demczyk - West Newton PA
John Bailey - Temple NH

Assignee:

The United States of America as represented by the Secretary of the Air
Force - Washington DC

International Classification:

C30B 1310

US Classification:

117 49

Abstract:

The present invention describes the growth of single crystals of non-congruently melting alloys, in particular, silicon-germanium of constant composition in a quartz ampoule by the use of CaCl. sub. 2 as an encapsulant for the liquid encapsulated zone melting (LEZM) technique. The zone melting process was modified with the addition of calcium chloride which acts as a liquid encapsulant at temperatures above 660. degree. C. so that the crystal can grow without sticking to the container. The calcium chloride encapsulant creates a non-wetting buffer layer between the quartz container and the SiGe charge material allowing single crystal growth of mixed alloys. The crystal growth system consists of a vertical tube RF furnace with a water cooled split-ring concentrator. The concentrator is 5 mm. Thick by 25 mm diameter and provides a high temperature melt zone with a "spike" profile.