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).

  • Publication number: 20160172481
    Abstract: 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: Application
    Filed: December 21, 2015
    Publication date: June 16, 2016
    Inventors: Michael MacMillan, Utpal K. Chakrabarti
  • Patent number: 9276069
    Abstract: 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: Grant
    Filed: November 26, 2013
    Date of Patent: March 1, 2016
    Assignee: Global Power Technologies Group, Inc.
    Inventor: Utpal K. Chakrabarti
  • Patent number: 9219122
    Abstract: 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: Grant
    Filed: March 13, 2014
    Date of Patent: December 22, 2015
    Assignee: Global Power Technologies Group, Inc.
    Inventors: Michael MacMillan, Utpal K. Chakrabarti
  • Patent number: 8871025
    Abstract: 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: Grant
    Filed: September 27, 2007
    Date of Patent: October 28, 2014
    Assignee: II-VI Incorporated
    Inventors: Avinash Gupta, Utpal K. Chakrabarti, Jihong Chen, Edward Semenas, Ping Wu
  • Publication number: 20140264382
    Abstract: 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: Application
    Filed: March 13, 2014
    Publication date: September 18, 2014
    Applicant: Global Power Device Company
    Inventors: Michael MacMillan, Utpal K. Chakrabarti
  • Publication number: 20140145211
    Abstract: 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: Application
    Filed: November 26, 2013
    Publication date: May 29, 2014
    Applicant: GLOBAL POWER DEVICES COMPANY
    Inventor: Utpal K. Chakrabarti
  • Publication number: 20100031877
    Abstract: 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: Application
    Filed: September 27, 2007
    Publication date: February 11, 2010
    Applicant: II-VI INCORPORATED
    Inventors: Avinash Gupta, Utpal K. Chakrabarti, Jihong Chen, Edward Semenas, Ping Wu
  • Patent number: 7612345
    Abstract: 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: Grant
    Filed: January 27, 2006
    Date of Patent: November 3, 2009
    Assignee: Endicott Interconnect Technologies, Inc.
    Inventors: Csaba Szeles, Scott E. Cameron, Vincent D. Mattera, Jr., Utpal K. Chakrabarti
  • Publication number: 20090250692
    Abstract: 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: Application
    Filed: April 7, 2009
    Publication date: October 8, 2009
    Applicant: EV PRODUCTS, INC.
    Inventors: Csaba Szeles, Utpal K. Chakrabarti
  • Publication number: 20090041648
    Abstract: 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: Application
    Filed: January 27, 2006
    Publication date: February 12, 2009
    Inventors: Csaba Szeles, Scott E. Cameron, Vincent D. Mattera, JR., Utpal K. Chakrabarti
  • Patent number: 6320265
    Abstract: 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: Grant
    Filed: April 12, 1999
    Date of Patent: November 20, 2001
    Assignee: Lucent Technologies Inc.
    Inventors: Utpal K. Chakrabarti, Gustav E. Derkits, Jr.
  • Patent number: 5346855
    Abstract: 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: Grant
    Filed: January 19, 1993
    Date of Patent: September 13, 1994
    Assignee: AT&T Bell Laboratories
    Inventors: Erin K. Byrne, Utpal K. Chakrabarti, Todd R. Hayes
  • Patent number: 4749255
    Abstract: 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: Grant
    Filed: December 9, 1985
    Date of Patent: June 7, 1988
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Utpal K. Chakrabarti, Aland K. Chin, George J. Przybylek, LeGrand G. Van Uitert, George J. Zydzik