Kedar P Gupta

6365225, Apr 2, 2002

Aug 17, 2000

09/642735

Mohan Chandra - Merrimack NH
Kedar P. Gupta - Hollis NH
Jonathan A. Talbott - Amherst NH
Ijaz Jafri - Nashua NH
Vishwanath Prasad - East Setauket NY

G.T. Equipment Technologies, Inc. - Nashua NH

B05D 722

427237, 42725518, 42725527, 427255393, 427314, 423349

A method and apparatus, and product by process, for the production of bulk polysilicon by a chemical vapor deposition process on a removable tube section. A quartz envelope and base plate form a CVD reactor enclosure, with external radiant heaters providing process heat through the wall of the reactor, and with process gas inlet and outlet ports located in the base plate. A tube section, preferably an EFG silicon tube-section, vertically emplaced on the base plate and capped to close the top is used as the reaction chamber. During the CVD process, deposition occurs on the inside surface of the chamber tube, the inner diameter of the deposit layer becoming increasingly smaller as the yield accumulates. In a two tube reactor, a smaller diameter, vertical middle tube is uniformly spaced and supported inside the chamber tube for fall flow of process gas over and under the middle tube so that deposition occurs on the three exposed tube surfaces. A co-axial core tube and heater mounted on the base plate provides yet more deposition surface area, improved thermal gradient in the reaction chamber, and greater thermal efficiency to the process.

7175685, Feb 13, 2007

Apr 15, 2003

10/413774

Alleppey V Hariharan - Austin TX, US
Mohan Chandra - Merrimack NH, US
Kedar P Gupta - Hollis NH, US

GT Solar Incorporated - Merrimack NH

C22C 28/00
B22F 1/00

75228, 419 66

A bulk silicon material for making silicon ingots, consisting of silicon pellets, and a method for making the pellets from an agglomerate-free source of high purity silicon powder by feeding a controlled amount of silicon powder that is free of intentional additives and binders into a pellet die, and dry compacting the powder at ambient temperature with pressure to produce a pellet that has a density of about 50–75% of the theoretical density of elemental silicon, a weight within a range of about 1. 0 gram to about 3. 0 grams and preferably of about 2. 3 grams, a diameter in the range of 10 mm to 20 mm and preferably of about 14 mm, and a height in the range of 5 mm to 15 mm and preferably of about 10 mm.

7540919, Jun 2, 2009

Mar 31, 2006

11/394970

Santhana Raghavan Parthasarathy - Nashua NH, US
Yuepeng Wan - Nashua NH, US
Carl Chartier - Manchester NH, US
Jonathan A Talbott - Amherst NH, US
Kedar P Gupta - Hollis NH, US

GT Solar Incorporated - Merrimack NH

C30B 25/12

117 95, 117 97, 427133, 427154, 4273722, 4274211, 4274281, 428213

A process for making silicon ingots using a multi-part, reusable, graphite crucible of at least two mold pieces configured for assembly into an open top mold having an interior surface functional as a mold cavity for receiving molten silicon; removing or reducing a prior applied release coating from the interior surface until a uniformly smooth finish is achieved; coating the interior surface with a first layer of release coating comprising silicon nitride; coating the interior surface with a second layer of release coat comprising silica suspended in water; coating the interior surface with a third layer of release coat comprising silicon nitride; curing the release coat on said crucible; casting a silicon ingot in the crucible; and then repeating the prior steps multiple times.

20070148034, Jun 28, 2007

Jan 30, 2007

11/668488

Kedar Gupta - Merrimack NH, US
Yuepeng Wan - Nashua NH, NH
Santhana Parthasarathy - Nashua NH, US
Chandra Khattak - Danvers MA, US

GT SOLAR INCORPORATED - Merrimack NH

C22C 29/18

420578000

A bulk silicon material for making silicon ingots, consisting of silicon pellets, and a method for making the pellets from an agglomerate-free source of high purity, ultra fine silicon powder by feeding a controlled amount of silicon powder into a pellet die, and dry compacting the powder at ambient temperature with pressure to produce a pellet that has a density of about 50-85% of the theoretical density of elemental silicon, a weight within a range of about 1.0 gram to about 3.0 grams, a diameter in the range of 10 mm to 20 mm and preferably of about 14 mm, and a height in the range of 5 mm to 15 mm and preferably of about 10 mm.

20090206233, Aug 20, 2009

Apr 7, 2009

12/419515

Santhana Raghavan Parthasarathy - Nashua NH, US
Yuepeng Wan - Nashua NH, US
Carl Chartier - Manchester NH, US
Jonathan A. Talbott - Amherst NH, US
Kedar Gupta - Hollis NH, US

GT SOLAR INCORPORATED - Merrimack NH

B29C 33/56

249115

A process for making silicon ingots using a multi-part, reusable, graphite crucible of at least two mold pieces configured for assembly into an open top mold having an interior surface functional as a mold cavity for receiving molten silicon; removing or reducing a prior applied release coating from the interior surface until a uniformly smooth finish is achieved; coating the interior surface with a first layer of release coating comprising silicon nitride; coating the interior surface with a second layer of release coat comprising silica suspended in water; coating the interior surface with a third layer of release coat comprising silicon nitride; curing the release coat on said crucible; casting a silicon ingot in the crucible; and then repeating the prior steps multiple times.

20100101387, Apr 29, 2010

Oct 22, 2009

12/588656

Kedar Prasad Gupta - Hollis NH, US
Govindhan Dhanaraj - Merrimack NH, US

B26D 9/00
C30B 15/20

83 39, 117217, 117216, 117 3

A controlled heat extraction system and method thereof is disclosed. In one embodiment, a system includes a housing to form a chamber. The system further includes a seed cooling component adapted to support a bottom of the crucible and to receive a coolant fluid to cool the supported portion of the crucible. The system also includes at least one heating element substantially surrounding the seed cooling component and the crucible to heat the crucible, where the seed cooling component along with the crucible is movable relative to the at least one heating element. Furthermore, the system includes an insulating element substantially surrounding the crucible, the seed cooling component and the at least one heating element. Additionally, the system includes a gradient control device (GCD) movable relative to the insulating element, the at least one heating element, the seed cooling component and the crucible over a range of positions.

20110044842, Feb 24, 2011

Oct 21, 2010

12/909353

Kedar P. Gupta - Merrimack NH, US
Yuepeng Wan - Nashua NH, US
Santhana Raghavan Parthasarathy - Nashua NH, US
Chandra Khattak - Danvers MA, US

GT SOLAR INCORPORATED - Merrimack NH

B22F 3/02

419 66

A method for making bulk silicon material consisting of silicon pellets for making silicon ingots from an agglomerate-free source of high purity, ultra fine silicon powder includes feeding a controlled amount of silicon powder into a pellet die and dry compacting the powder at ambient temperature with pressure to produce a pellet that has a density of about 50-85% of the theoretical density of elemental silicon, a weight within a range of about 1.0 gram to about 3.0 grams, a diameter in the range of 10 mm to 20 mm and preferably of about 14 mm, and a height in the range of 5 mm to 15 mm and preferably of about 10 mm.

20110179992, Jul 28, 2011

Oct 21, 2010

12/909471

Govindhan Dhanaraj - Merrimack NH, US
Kedar Prasad Gupta - Hollis NH, US

C30B 11/02

117 81

Methods and systems related to an improved controlled heat extraction system for crystal growth, such as sapphire crystal growth are described, including methods and systems for mechanical probe-based and pyrometer-based inspection and automation processes, methods and systems for avoiding fusion of components, methods and systems for purging an inspection window, and methods and systems related to alternative crucible shapes.