Patents by Inventor Utpal K. Chakrabarti
Utpal K. Chakrabarti has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Publication number: 20160172481Abstract: Methods, systems, and devices are disclosed for thermal processing of silicon carbide semiconductor devices. In one aspect, a method for fabricating a silicon carbide semiconductor device includes forming a thin epitaxial layer of a nitrogen and phosphorous co-doped SiC material on a SiC epitaxial layer formed on a SiC substrate, and thermally growing an oxide layer to form an insulator material on the nitrogen and phosphorous co-doped SiC epitaxial layer, in which the thermally growing the oxide layer results in at least partially consuming the nitrogen and phosphorous co-doped SiC epitaxial layer in the oxide layer to produce an interface including nitrogen and phosphorous between the SiC epitaxial layer and the oxide layer.Type: ApplicationFiled: December 21, 2015Publication date: June 16, 2016Inventors: Michael MacMillan, Utpal K. Chakrabarti
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Patent number: 9276069Abstract: Methods, systems, and devices are disclosed for implementing high power circuits and semiconductor devices. In one aspect, a method for fabricating a silicon carbide (SiC) device includes forming a thin layer of a protection material over a SiC substrate, in which the protection material has a lattice constant that substantially matches a lattice constant of SiC and the thin layer has a thickness of less than a critical layer thickness for the protection material over SiC to form a uniform interface between the protection material and SiC, forming a layer of an insulator material over the thin layer of the protection material, and forming one or more transistor structures over the insulator material.Type: GrantFiled: November 26, 2013Date of Patent: March 1, 2016Assignee: Global Power Technologies Group, Inc.Inventor: Utpal K. Chakrabarti
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Patent number: 9219122Abstract: Methods, systems, and devices are disclosed for thermal processing of silicon carbide semiconductor devices. In one aspect, a method for fabricating a silicon carbide semiconductor device includes forming a thin epitaxial layer of a nitrogen and phosphorous co-doped SiC material on a SiC epitaxial layer formed on a SiC substrate, and thermally growing an oxide layer to form an insulator material on the nitrogen and phosphorous co-doped SiC epitaxial layer, in which the thermally growing the oxide layer results in at least partially consuming the nitrogen and phosphorous co-doped SiC epitaxial layer in the oxide layer to produce an interface including nitrogen and phosphorous between the SiC epitaxial layer and the oxide layer.Type: GrantFiled: March 13, 2014Date of Patent: December 22, 2015Assignee: Global Power Technologies Group, Inc.Inventors: Michael MacMillan, Utpal K. Chakrabarti
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Patent number: 8871025Abstract: In a crystal growth method, a seed crystal 8 and a source material 4 are provided in spaced relation inside of a growth crucible 6. Starting conditions for the growth of a crystal 14 in the growth crucible 6 are then established therein. The starting conditions include: a suitable gas inside the growth crucible 6, a suitable pressure of the gas inside the growth crucible 6, and a suitable temperature in the growth crucible 6 that causes the source material 4 to sublimate and be transported via a temperature gradient in the growth crucible 6 to the seed crystal 8 where the sublimated source material precipitates. During growth of the crystal 14 inside the growth crucible 6, at least one of the following growth conditions are intermittently changed inside the growth crucible 6 a plurality of times: the gas in the growth crucible 6, the pressure of the gas in the growth crucible 6, and the temperature in the growth crucible 6.Type: GrantFiled: September 27, 2007Date of Patent: October 28, 2014Assignee: II-VI IncorporatedInventors: Avinash Gupta, Utpal K. Chakrabarti, Jihong Chen, Edward Semenas, Ping Wu
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Publication number: 20140264382Abstract: Methods, systems, and devices are disclosed for thermal processing of silicon carbide semiconductor devices. In one aspect, a method for fabricating a silicon carbide semiconductor device includes forming a thin epitaxial layer of a nitrogen and phosphorous co-doped SiC material on a SiC epitaxial layer formed on a SiC substrate, and thermally growing an oxide layer to form an insulator material on the nitrogen and phosphorous co-doped SiC epitaxial layer, in which the thermally growing the oxide layer results in at least partially consuming the nitrogen and phosphorous co-doped SiC epitaxial layer in the oxide layer to produce an interface including nitrogen and phosphorous between the SiC epitaxial layer and the oxide layer.Type: ApplicationFiled: March 13, 2014Publication date: September 18, 2014Applicant: Global Power Device CompanyInventors: Michael MacMillan, Utpal K. Chakrabarti
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Publication number: 20140145211Abstract: Methods, systems, and devices are disclosed for implementing high power circuits and semiconductor devices. In one aspect, a method for fabricating a silicon carbide (SiC) device includes forming a thin layer of a protection material over a SiC substrate, in which the protection material has a lattice constant that substantially matches a lattice constant of SiC and the thin layer has a thickness of less than a critical layer thickness for the protection material over SiC to form a uniform interface between the protection material and SiC, forming a layer of an insulator material over the thin layer of the protection material, and forming one or more transistor structures over the insulator material.Type: ApplicationFiled: November 26, 2013Publication date: May 29, 2014Applicant: GLOBAL POWER DEVICES COMPANYInventor: Utpal K. Chakrabarti
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Publication number: 20100031877Abstract: In a crystal growth method, a seed crystal 8 and a source material 4 are provided in spaced relation inside of a growth crucible 6. Starting conditions for the growth of a crystal 14 in the growth crucible 6 are then established therein. The starting conditions include: a suitable gas inside the growth crucible 6, a suitable pressure of the gas inside the growth crucible 6, and a suitable temperature in the growth crucible 6 that causes the source material 4 to sublimate and be transported via a temperature gradient in the growth crucible 6 to the seed crystal 8 where the sublimated source material precipitates. During growth of the crystal 14 inside the growth crucible 6, at least one of the following growth conditions are intermittently changed inside the growth crucible 6 a plurality of times: the gas in the growth crucible 6, the pressure of the gas in the growth crucible 6, and the temperature in the growth crucible 6.Type: ApplicationFiled: September 27, 2007Publication date: February 11, 2010Applicant: II-VI INCORPORATEDInventors: Avinash Gupta, Utpal K. Chakrabarti, Jihong Chen, Edward Semenas, Ping Wu
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Patent number: 7612345Abstract: A radiation detector crystal is made from CdxZn1-xTe, where 0?x?1; an element from column III or column VII of the periodic table, desirably in a concentration of about 1 to 10,000 atomic parts per billion; and the element Ruthenium (Ru), the element Osmium (Os) or the combination of Ru and Os, desirably in a concentration of about 1 to 10,000 atomic parts per billion using a conventional crystal growth method, such as, for example, the Bridgman method, the gradient freeze method, the electro-dynamic gradient freeze method, the so-call traveling heater method or by the vapor phase transport method. The crystal can be used as the radiation detecting element of a radiation detection device configured to detect and process, without limitation, X-ray and Gamma ray radiation events.Type: GrantFiled: January 27, 2006Date of Patent: November 3, 2009Assignee: Endicott Interconnect Technologies, Inc.Inventors: Csaba Szeles, Scott E. Cameron, Vincent D. Mattera, Jr., Utpal K. Chakrabarti
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Publication number: 20090250692Abstract: A room temperature radiation detector is made from a semi-insulating Cd1-xZnxTe crystal, where 0?x?1, having a first electrode made of Pt or Au on one surface of the crystal and a second electrode of Al, Ti or In on another surface of the crystal. In use of the crystal to detect radiation events, an electrical bias is applied between the first and second electrodes.Type: ApplicationFiled: April 7, 2009Publication date: October 8, 2009Applicant: EV PRODUCTS, INC.Inventors: Csaba Szeles, Utpal K. Chakrabarti
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Publication number: 20090041648Abstract: A radiation detector crystal is made from CdxZn1-xTe, where 0?x?1; an element from column III or column VII of the periodic table, desirably in a concentration of about 1 to 10,000 atomic parts per billion; and the element Ruthenium (Ru), the element Osmium (Os) or the combination of Ru and Os, desirably in a concentration of about 1 to 10,000 atomic parts per billion using a conventional crystal growth method, such as, for example, the Bridgman method, the gradient freeze method, the electro-dynamic gradient freeze method, the so-call traveling heater method or by the vapor phase transport method. The crystal can be used as the radiation detecting element of a radiation detection device configured to detect and process, without limitation, X-ray and Gamma ray radiation events.Type: ApplicationFiled: January 27, 2006Publication date: February 12, 2009Inventors: Csaba Szeles, Scott E. Cameron, Vincent D. Mattera, JR., Utpal K. Chakrabarti
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Patent number: 6320265Abstract: A semiconductor device includes a semiconductor layer, prelayer, refractory layer, and conductive layer. The conductive layer includes an ohmic contact layer, and may also include a barrier layer, of a highly stable, low-resistance element or compound, such as Au or Ti, which is formed on the refractory layer. The refractory layer is a material that does not react with, or dissociate from, either the prelayer or the conductive layer when the semiconductor device is exposed to relatively high temperatures. The refractory layer material may be metal suicides, phosphides, or nitrides. The material of the prelayer is selected to minimize strain between the prelayer, the refractory layer and the semiconductor layer to provide a relatively strong bond between the refractory layer and semiconductor. The prelayer may be selected to provide relatively high current injection to the semiconductor, and may further form a low Schottky barrier height with the semiconductor.Type: GrantFiled: April 12, 1999Date of Patent: November 20, 2001Assignee: Lucent Technologies Inc.Inventors: Utpal K. Chakrabarti, Gustav E. Derkits, Jr.
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Patent number: 5346855Abstract: Disclosed is a method of making InP-based DFB lasers that can reliably mitigate or substantially prevent erosion of the grating during overgrowth. The method comprises contacting, prior to overgrowth, the grating with a sulfurcontaining aqueous medium, e.g., 80 parts by weight H.sub.2 O/20 parts by weight ammonium sulfide.Type: GrantFiled: January 19, 1993Date of Patent: September 13, 1994Assignee: AT&T Bell LaboratoriesInventors: Erin K. Byrne, Utpal K. Chakrabarti, Todd R. Hayes
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Patent number: 4749255Abstract: Disclosed is a device including a surface coating for passivation or anti-reflection, and a method of manufacture. The coating comprises ZrO.sub.2 doped with yttrium, magnesium or calcium. The doped ZrO.sub.2 is preferably deposited on the device surface by electron-beam evaporation from a single crystal source of ZrO.sub.2 and Y.sub.2 O.sub.3, MgO or CaO.Type: GrantFiled: December 9, 1985Date of Patent: June 7, 1988Assignee: American Telephone and Telegraph Company, AT&T Bell LaboratoriesInventors: Utpal K. Chakrabarti, Aland K. Chin, George J. Przybylek, LeGrand G. Van Uitert, George J. Zydzik