Single-crystal – oriented-crystal – and epitaxy growth processes; – Processes of growth from liquid or supercritical state – Havin growth from molten state
Reexamination Certificate
2008-04-29
2008-04-29
Kunemund, Robert (Department: 1792)
Single-crystal, oriented-crystal, and epitaxy growth processes;
Processes of growth from liquid or supercritical state
Havin growth from molten state
C117S082000, C117S083000, C117S940000
Reexamination Certificate
active
10977523
ABSTRACT:
An improved technique that reduces the potential for trapped impurities and/or ensuring desired stoichiometry of a grown crystal. Improved contaminant removal is obtained by bubbling a scavenger gas, such as fluorine gas or hydrogen fluoride gas, through a melt of alkaline- or alkali-earth halides, to improve the purity of the melt by removing more volatile metal halides and oxygen contained within the melt. By reacting after the raw material has melted, any oxygen or metal impurities trapped in the raw material is free to react with the scavenger. A desired stoichiometry is achieved as the alkaline- or alkali-earth metals react with the halide in the scavenger gas. Decreasing the amount of impurities in the melt, and using a desired stoichiometeric melt, improves the radiation hardness and transmission properties of resulting ingot grown from the purified raw material. Additionally, this method may decrease the amount of time needed for outgassing. The method may also be used to form a high purity pre-melt, which in turn may be used to grow an ingot with higher purity.
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Written Opinion from International Patent Application No. PCT/US2005/037892.
R. C. Pastor et al., Crystal Growth of Alkaline Earth Fluorides in a Reactive Atmosphere PART II, Mat. Res. Bull., vol. 11, pp. 1037-1042, 1976. (XP 002381051).
Kunemund Robert
Renner , Otto, Boisselle & Sklar, LLP
Saint-Gobain Ceramics & Plastics, Inc.
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