Crystal Systems Corporation

Gt Crystal Systems, LLC

US Government As Represented by the Secretary of the Army

Gtat Corporation

Ghemini Technologies

Frederick Schmid

Chandra P Khattak

David B Joyce

Maynard B Smith

James W McCauley

Hui Zhang

Dennis J Viechnicki

Cody Riopel

Charles P Gazzara

Vernon E White

Vladimir Gorbulev

John Brouillette

Daniel P Betty

Jarda L Caslavsky

Ryan Philpott

John H Wohlgemuth

A method of producing a crystalline material is provided that may include providing a crystal growth apparatus comprising a chamber, a hot zone, and a muffle. The hot zone may be disposed within the chamber and include at least one heating system, at least one heat removal system, and a crucible containing feedstock. Additionally, the method may include providing a muffle that surrounds at least two sides of the crucible to ensure uniform temperature distribution through the feedstock during crystal growth to allow the crystalline material to be grown with a square or rectangular shaped cross section.

Technique for controlling temperature uniformity in crystal growth apparatus

A sapphire crystal growth apparatus is provided that includes a chamber, a hot zone and a muffle. More specifically, the hot zone is disposed within the chamber and includes at least one heating system, at least one heat removal system, and a crucible containing feedstock. Additionally, a muffle that surrounds at least two sides of the crucible is also provided to ensure uniform temperature distribution through the feedstock during crystal growth to allow the crystalline material to be grown with a square or rectangular shaped cross section.

A method for minimizing unwanted ancillary reactions in a vacuum furnace used to process a material, such as growing a crystal. The process is conducted in a furnace chamber environment in which helium is admitted to the furnace chamber at a flow rate to flush out impurities and at a predetermined pressure to achieve thermal stability in a heat zone, to minimize heat flow variations and to minimize temperature gradients in the heat zone. During cooldown helium pressure is used to reduce thermal gradients in order to increase cooldown rates.

High-temperature process improvements using helium under regulated pressure

A method and apparatus for refining metallurgical silicon to produce solar grade silicon for use in photovoltaic cells. A crucible in a vacuum furnace receives a mixture of metallurgical silicon and a reducing agent such as calcium disilicide. The mix is melted in non-oxidizing conditions within the furnace under an argon partial pressure. After melting, the argon partial pressure is decreased to produce boiling and the process ends with directional solidification. The process reduces impurities, such as phosphorus, to a level compatible with solar-grade silicon and reduces other impurities significantly.

Method and apparatus for refining metallurgical grade silicon to produce solar grade silicon

To reduce the heat input to the bottom of the crucible and to control heat extraction independently of heat input, a shield can be raised between a heating element and a crucible at a controlled speed as the crystal grows. Other steps could include moving the crucible, but this process can avoid having to move the crucible. A temperature gradient is produced by shielding only a portion of the heating element; for example, the bottom portion of a cylindrical element can be shielded to cause heat transfer to be less in the bottom of the crucible than at the top, thereby causing a stabilizing temperature gradient in the crucible.

System and method for crystal growing

A cutting machine has a blade mounted for reciprocating movement. A workpiece is rotated while the blade is reciprocated, and then the workpiece is rotated through smaller angles to complete the cut. A holder is attached to partially cut slices of the workpiece.

Method and apparatus for cutting workpieces

An apparatus for purifying metallurgical grade silicon to produce solar grade silicon has a container for holding molten silicon and one or more torches for providing oxygen and hydrogen gas to heat the molten silicon so that the reaction time is prolonged, to create turbulence, and to introduce silica powder and water vapor for reactions with molten silicon. The molten silicon is then directionally solidified.

Method and apparatus for purifying silicon

An apparatus for purifying metallurgical grade silicon to produce solar grade silicon has a container for holding molten silicon and one or more submergible torches for providing a flame surrounded by inert gas to heat the molten silicon so that the reaction time is prolonged, to create turbulence, and to introduce silica powder and water vapor for reactions with molten silicon. The molten silicon is then directionally solidified by providing the container in a coolant tank and controlling the coolant level with controllable valves so that further purification is achieved by segregating impurities.

Method for purifying silicon

A radial cut profile is achieved while advancing a workpiece at a substantially constant rate in a direction towards a cutting blade by moving the workpiece vertically relative to the blade in synchronization with the oscillation of the workpiece. The vertical movement is provided by a linkage including two links pivotally connected to each other. The other end of one link is pivotally connected to the feed mechanism. The other end of the other link is fixed relative to the oscillating workpiece.

Method and apparatus to produce a radial cut profile

A cutting blade the core of which is generally tear-drop shaped in cross-section. The sides of the tear-drop shaped core form an included angle of not less than about 5 degrees (and typically not less than about 9 degrees), and abrasive is provided essentially on only the wide bottom surface of the core.

Shaped blades

A high temperature heat exchanger is used with the Czochralski crystal growing method to control the heat extraction from crystal silicon ingots as they are grown. The high temperature heat exchanger also acts as a shaping die so that silicon bars, or ingots, of various shapes, including square, circular, rectangular or ribbon, can be produced by shaping during the growth stage.

Method and apparatus for growing shaped crystals

A process that, without doping of PBN crucibles, produces semi-insulating GaAs having low, or essentially no, dislocation density; and in which the crystal may be in situ annealed after growth. The process is a variant of the Heat Exchanger Method (HEM) disclosed in U.S. Pat. No. 3,898,051. Crack-free, semi-insulating GaAs crystals having low dislocation density are grown from presynthesized undoped GaAs meltstock in sealed quartz (vitreous silica) crucibles, without the need for an encapsulant. One aspect of the invention features seeded growth of &lt;100&gt; orientation crystals having a dislocation density 1-2 orders of magnitude less than that of the seed; in another aspect, crystals having fewer than 500 dislocations/cam.sup.2 in their center column are grown without a seed.

Gallium arsenide crystal growth

A wafering machine having a multiplicity of wire cutting blades supported by a bladehead reciprocally moving past a workpiece supported by a holder that rocks about an axis perpendicular to the wires at a frequency less than the reciprocation of the bladehead.

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Marblehead, MA, United States of America

Frederick Schmid