Patents by Inventor Tangali S. Sudarshan

Tangali S. Sudarshan 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).

  • Patent number: 11680333
    Abstract: Methods for forming a graphene film on a silicon carbide material are provided, along with the resulting coated materials. The method can include: heating the silicon carbide material to a growth temperature (e.g., about 1,000° C. to about 2,200° C.), and exposing the silicon carbide material to a growth atmosphere comprising a halogen species. The halogen species reacts with the silicon carbide material to remove silicon therefrom. The halogen species can comprise fluorine (e.g., SiF4, etc.), chlorine (e.g., SiCl4), or a mixture thereof.
    Type: Grant
    Filed: February 14, 2014
    Date of Patent: June 20, 2023
    Assignee: University of South Carolina
    Inventors: Tangali S. Sudarshan, Tawhid Rana, MVS Chandrashekhar
  • Publication number: 20200056302
    Abstract: Methods are provided for growing basal plane dislocation (BPD)-free SiC device-ready epilayers, particularly suitable for 4H-SiC devices. The devices are formed via a substantially 100% conversion of BPDs to threading edge dislocations (TEDs) while pinning the conversion point below the epilayer interface. Methods include the formation of a recombination layer on a previously formed and etched buffer layer. Devices allow for improved reliability and efficiency of high voltage switches used in the day-to-day applications such as inverters, uninterrupted power supplies, and other high power handling devices employed in hybrid electric vehicles, aircraft electronic systems, etc. by enabling the manufacture of smaller, lighter, and more efficient, high power SiC devices in a cost effective, reliable platform.
    Type: Application
    Filed: March 1, 2018
    Publication date: February 20, 2020
    Inventors: ANUSHA BALACHANDRAN, MVS CHANDRASHEKHAR, TANGALI S. SUDARSHAN
  • Patent number: 10260166
    Abstract: Methods for forming an epilayer on a surface of a substrate are generally provided. For example, a substrate can be positioned within a hot wall CVD chamber (e.g., onto a susceptor within the CVD chamber). At least two source gases can then be introduced into the hot wall CVD chamber such that, upon decomposition, fluorine atoms, carbon atoms, and silicon atoms are present within the CVD chamber. The epilayer comprising SiC can then be grown on the surface of the substrate in the presence of the fluorine atoms.
    Type: Grant
    Filed: October 11, 2017
    Date of Patent: April 16, 2019
    Assignee: University of South Carolina
    Inventors: Tangali S. Sudarshan, Tawhid Rana, Haizheng Song
  • Patent number: 9966491
    Abstract: A bi-polar device is provided, along with methods of making the same. The bi-polar device can include a semiconductor substrate doped with a first dopant, a semiconductor layer on the first surface of the semiconductor substrate, and a Schottky barrier layer on the semiconductor layer. The method of forming a bi-polar device can include: forming a semiconductor layer on a first surface of a semiconductor substrate, where the semiconductor substrate comprises a first dopant and where the semiconductor layer comprises a second dopant that has an opposite polarity than the first dopant; and forming a Schottky barrier layer on a first portion of the semiconductor layer while leaving a second portion of the semiconductor layer exposed.
    Type: Grant
    Filed: February 22, 2016
    Date of Patent: May 8, 2018
    Assignee: University of South Carolina
    Inventors: MVS Chandrashekhar, Tangali S. Sudarshan, Sabih U. Omar, Gabriel Brown, Shamaita S. Shetu
  • Publication number: 20180044816
    Abstract: Methods for forming an epilayer on a surface of a substrate are generally provided. For example, a substrate can be positioned within a hot wall CVD chamber (e.g., onto a susceptor within the CVD chamber). At least two source gases can then be introduced into the hot wall CVD chamber such that, upon decomposition, fluorine atoms, carbon atoms, and silicon atoms are present within the CVD chamber. The epilayer comprising SiC can then be grown on the surface of the substrate in the presence of the fluorine atoms.
    Type: Application
    Filed: October 11, 2017
    Publication date: February 15, 2018
    Inventors: Tangali S. Sudarshan, Haizheng Song, Tawhid Rana
  • Patent number: 9885124
    Abstract: Methods for forming an epilayer on a surface of a substrate are generally provided. For example, a substrate can be positioned within a hot wall CVD chamber (e.g., onto a susceptor within the CVD chamber). At least two source gases can then be introduced into the hot wall CVD chamber such that, upon decomposition, fluorine atoms, carbon atoms, and silicon atoms are present within the CVD chamber. The epilayer comprising SiC can then be grown on the surface of the substrate in the presence of the fluorine atoms.
    Type: Grant
    Filed: November 20, 2012
    Date of Patent: February 6, 2018
    Assignee: University of South Carolina
    Inventors: Tangali S. Sudarshan, Haizheng Song, Tawhid Rana
  • Patent number: 9842898
    Abstract: A method of growing an epitaxial layer on a substrate is generally provided. According to the method, the substrate is heated in a chemical vapor deposition chamber to a growth temperature in the presence of a carbon source gas, then the epitaxial layer is grown on the substrate at the growth temperature, and finally the substrate is cooled in a chemical vapor deposition chamber to at least about 80% of the growth temperature in the presence of a carbon source gas. Substrates formed from this method can have a carrier lifetime between about 0.25 ?s and about 9.9 ?s.
    Type: Grant
    Filed: October 3, 2013
    Date of Patent: December 12, 2017
    Assignee: University of South Carolina
    Inventors: Tangali S. Sudarshan, Amitesh Srivastava
  • Patent number: 9644288
    Abstract: Non-destructive pretreatment methods are generally provided for a surface of a SiC substrate with substantially no degradation of surface morphology thereon. In one particular embodiment, a molten suspension mixture (e.g., including KOH (or KOH eutectic) and a buffering agent) is applied directly onto the surface of the SiC substrate to form a treated surface thereon. An epitaxial film (e.g., SiC) can then be grown on the treated surface to achieve very high (e.g., up to and including 100%) BPD to TED conversion rate close to the epilayer/substrate interface.
    Type: Grant
    Filed: December 2, 2014
    Date of Patent: May 9, 2017
    Assignee: University of South Carolina
    Inventors: Tangali S. Sudarshan, Haizheng Song, Tawhid Rana
  • Patent number: 9644287
    Abstract: Non-destructive pretreatment methods are generally provided for a surface of a SiC substrate with substantially no degradation of surface morphology thereon. In one particular embodiment, a molten mixture (e.g., including KOH and a buffering agent) is applied directly onto the surface of the SiC substrate to form a treated surface thereon. An epitaxial film (e.g., SiC) can then be grown on the treated surface to achieve very high (e.g., up to and including 100%) BPD to TED conversion rate close to the epilayer/substrate interface.
    Type: Grant
    Filed: December 2, 2014
    Date of Patent: May 9, 2017
    Assignee: University of South Carolina
    Inventors: Tangali S. Sudarshan, Haizheng Song, Tawhid Rana
  • Patent number: 9570560
    Abstract: An electronic device includes a silicon carbide layer having a first conductivity type and a main junction adjacent a surface of the silicon carbide layer, and a junction termination region at the surface of the silicon carbide layer adjacent the main junction. Charge in the junction termination region decreases with lateral distance from the main junction, and a maximum charge in the junction termination region may be less than about 2×1014 cm?2.
    Type: Grant
    Filed: December 11, 2013
    Date of Patent: February 14, 2017
    Assignees: Cree, Inc., The University of South Carolina
    Inventors: Qingchun Zhang, Anant K. Agarwal, Tangali S. Sudarshan, Alexander Bolotnikov
  • Publication number: 20160315211
    Abstract: A bi-polar device is provided, along with methods of making the same. The bi-polar device can include a semiconductor substrate doped with a first dopant, a semiconductor layer on the first surface of the semiconductor substrate, and a Schottky barrier layer on the semiconductor layer. The method of forming a bi-polar device can include: forming a semiconductor layer on a first surface of a semiconductor substrate, where the semiconductor substrate comprises a first dopant and where the semiconductor layer comprises a second dopant that has an opposite polarity than the first dopant; and forming a Schottky barrier layer on a first portion of the semiconductor layer while leaving a second portion of the semiconductor layer exposed.
    Type: Application
    Filed: February 22, 2016
    Publication date: October 27, 2016
    Inventors: MVS Chandrashekhar, Tangali S. Sudarshan, Sabih U. Omar, Gabriel Brown, Shamaita S. Shetu
  • Publication number: 20150368827
    Abstract: Methods for forming a graphene film on a silicon carbide material are provided, along with the resulting coated materials. The method can include: heating the silicon carbide material to a growth temperature (e.g., about 1,000° C. to about 2,200° C.), and exposing the silicon carbide material to a growth atmosphere comprising a halogen species. The halogen species reacts with the silicon carbide material to remove silicon therefrom. The halogen species can comprise fluorine (e.g., SiF4, etc.), chlorine (e.g., SiCl4), or a mixture thereof.
    Type: Application
    Filed: February 14, 2014
    Publication date: December 24, 2015
    Inventors: Tangali S. Sudarshan, Tawhid Rana, MV. S. Chandrashekhar
  • Publication number: 20150128850
    Abstract: Non-destructive pretreatment methods are generally provided for a surface of a SiC substrate with substantially no degradation of surface morphology thereon. In one particular embodiment, a molten suspension mixture (e.g., including KOH (or KOH eutectic) and a buffering agent) is applied directly onto the surface of the SiC substrate to form a treated surface thereon. An epitaxial film (e.g., SiC) can then be grown on the treated surface to achieve very high (e.g., up to and including 100%) BPD to TED conversion rate close to the epilayer/substrate interface.
    Type: Application
    Filed: December 2, 2014
    Publication date: May 14, 2015
    Inventors: Tangali S. Sudarshan, Haizheng Song, Tawhid Rana
  • Publication number: 20150129897
    Abstract: Non-destructive pretreatment methods are generally provided for a surface of a SiC substrate with substantially no degradation of surface morphology thereon. In one particular embodiment, a molten mixture (e.g., including KOH and a buffering agent) is applied directly onto the surface of the SiC substrate to form a treated surface thereon. An epitaxial film (e.g., SiC) can then be grown on the treated surface to achieve very high (e.g., up to and including 100%) BPD to TED conversion rate close to the epilayer/substrate interface.
    Type: Application
    Filed: December 2, 2014
    Publication date: May 14, 2015
    Inventors: Tangali S. Sudarshan, Haizheng Song, Tawhid Rana
  • Patent number: 8900979
    Abstract: Non-destructive pretreatment methods are generally provided for a surface of a SiC substrate with substantially no degradation of surface morphology thereon. In one particular embodiment, a molten mixture (e.g., including KOH and a buffering agent) is applied directly onto the surface of the SiC substrate to form a treated surface thereon. An epitaxial film (e.g., SiC) can then be grown on the treated surface to achieve very high (e.g., up to and including 100%) BPD to TED conversion rate close to the epilayer/substrate interface.
    Type: Grant
    Filed: November 20, 2012
    Date of Patent: December 2, 2014
    Assignee: University of South Carolina
    Inventors: Tangali S. Sudarshan, Haizheng Song, Tawhid Rana
  • Publication number: 20140338588
    Abstract: Methods for forming an epilayer on a surface of a substrate are generally provided. For example, a substrate can be positioned within a hot wall CVD chamber (e.g., onto a susceptor within the CVD chamber). At least two source gases can then be introduced into the hot wall CVD chamber such that, upon decomposition, fluorine atoms, carbon atoms, and silicon atoms are present within the CVD chamber. The epilayer comprising SiC can then be grown on the surface of the substrate in the presence of the fluorine atoms.
    Type: Application
    Filed: November 20, 2012
    Publication date: November 20, 2014
    Inventors: Tangali S. Sudarshan, Haizheng Song, Tawhid Rana
  • Publication number: 20140231826
    Abstract: A method of growing an epitaxial layer on a substrate is generally provided. According to the method, the substrate is heated in a chemical vapor deposition chamber to a growth temperature in the presence of a carbon source gas, then the epitaxial layer is grown on the substrate at the growth temperature, and finally the substrate is cooled in a chemical vapor deposition chamber to at least about 80% of the growth temperature in the presence of a carbon source gas. Substrates formed from this method can have a carrier lifetime between about 0.25 ?s and about 9.9 ?s.
    Type: Application
    Filed: October 3, 2013
    Publication date: August 21, 2014
    Inventors: Tangali S. Sudarshan, Amitesh Srivastava
  • Publication number: 20140097450
    Abstract: An electronic device includes a silicon carbide layer having a first conductivity type and a main junction adjacent a surface of the silicon carbide layer, and a junction termination region at the surface of the silicon carbide layer adjacent the main junction. Charge in the junction termination region decreases with lateral distance from the main junction, and a maximum charge in the junction termination region may be less than about 2×1014 cm?2.
    Type: Application
    Filed: December 11, 2013
    Publication date: April 10, 2014
    Applicants: The University of South Carolina, Cree, Inc.
    Inventors: Qingchun Zhang, Anant K. Agarwal, Tangali S. Sudarshan, Alexander Bolotnikov
  • Patent number: 8637386
    Abstract: An electronic device includes a silicon carbide layer having a first conductivity type and a main junction adjacent a surface of the silicon carbide layer, and a junction termination region at the surface of the silicon carbide layer adjacent the main junction. Charge in the junction termination region decreases with lateral distance from the main junction, and a maximum charge in the junction termination region may be less than about 2×1014 cm?2.
    Type: Grant
    Filed: March 8, 2010
    Date of Patent: January 28, 2014
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Anant K. Agarwal, Tangali S. Sudarshan, Alexander Bolotnikov
  • Patent number: 8574528
    Abstract: A method of growing an epitaxial layer on a substrate is generally provided. According to the method, the substrate is heated in a chemical vapor deposition chamber to a growth temperature in the presence of a carbon source gas, then the epitaxial layer is grown on the substrate at the growth temperature, and finally the substrate is cooled in a chemical vapor deposition chamber to at least about 80% of the growth temperature in the presence of a carbon source gas. Substrates formed from this method can have a carrier lifetime between about 0.25 ?s and about 9.9 ?s.
    Type: Grant
    Filed: September 7, 2010
    Date of Patent: November 5, 2013
    Assignee: University of South Carolina
    Inventors: Tangali S. Sudarshan, Amitesh Srivastava