Patents by Inventor Sarit Dhar

Sarit Dhar 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: 9984894
    Abstract: Methods of forming a semiconductor structure include providing an insulation layer on a semiconductor layer and diffusing cesium ions into the insulation layer from a cesium ion source outside the insulation layer. A MOSFET including an insulation layer treated with cesium ions may exhibit increased inversion layer mobility.
    Type: Grant
    Filed: August 3, 2011
    Date of Patent: May 29, 2018
    Assignees: Cree, Inc., Auburn University
    Inventors: Sarit Dhar, Sei-Hyung Ryu, Anant Agarwal, John Robert Williams
  • Patent number: 9478616
    Abstract: Semiconductor devices having a high performance channel and method of fabrication thereof are disclosed. Preferably, the semiconductor devices are Metal-Oxide-Semiconductor (MOS) devices, and even more preferably the semiconductor devices are Silicon Carbide (SiC) MOS devices. In one embodiment, a semiconductor device includes a SiC substrate of a first conductivity type, a first well of a second conductivity type, a second well of the second conductivity type, and a surface diffused channel of the second conductivity type formed at the surface of semiconductor device between the first and second wells. A depth and doping concentration of the surface diffused channel are controlled to provide increased carrier mobility for the semiconductor device as compared to the same semiconductor device without the surface diffused channel region when in the on-state while retaining a turn-on, or threshold, voltage that provides normally-off behavior.
    Type: Grant
    Filed: March 3, 2011
    Date of Patent: October 25, 2016
    Assignee: Cree, Inc.
    Inventors: Sarit Dhar, Sei-Hyung Ryu, Lin Cheng, Anant Agarwal
  • Patent number: 9396946
    Abstract: Embodiments of a semiconductor device having increased channel mobility and methods of manufacturing thereof are disclosed. In one embodiment, the semiconductor device includes a substrate including a channel region and a gate stack on the substrate over the channel region. The gate stack includes an alkaline earth metal. In one embodiment, the alkaline earth metal is Barium (Ba). In another embodiment, the alkaline earth metal is Strontium (Sr). The alkaline earth metal results in a substantial improvement of the channel mobility of the semiconductor device.
    Type: Grant
    Filed: September 9, 2011
    Date of Patent: July 19, 2016
    Assignee: Cree, Inc.
    Inventors: Sarit Dhar, Lin Cheng, Sei-Hyung Ryu, Anant Agarwal, John Williams Palmour, Erik Maki, Jason Gurganus, Daniel Jenner Lichtenwalner
  • Patent number: 9343540
    Abstract: A metal-insulator-semiconductor field-effect transistor (MISFET) includes a SiC layer with source and drain regions of a first conductivity type spaced apart therein. A first gate insulation layer is on the SiC layer and has a net charge along an interface with the SiC layer that is the same polarity as majority carriers of the source region. A gate contact is on the first gate insulation layer over a channel region of the SiC layer between the source and drain regions. The net charge along the interface between the first gate insulation layer and the SiC layer may deplete majority carriers from an adjacent portion of the channel region between the source and drain regions in the SiC layer, which may increase the threshold voltage of the MISFET and/or increase the electron mobility therein.
    Type: Grant
    Filed: August 14, 2014
    Date of Patent: May 17, 2016
    Assignee: Cree, Inc.
    Inventors: Sarit Dhar, Sei-Hyung Ryu
  • Patent number: 9312343
    Abstract: A transistor may include a semiconductor drift layer of a first semiconductor material and a semiconductor channel layer on the semiconductor drift layer. The semiconductor channel layer may include a second semiconductor material different than the first semiconductor material. A semiconductor interconnection layer may be electrically coupled between the semiconductor drift layer and the semiconductor channel layer, and the semiconductor interconnection layer may include a third semiconductor material different than the first and second semiconductor materials. In addition, a control electrode may be provided on the semiconductor channel layer.
    Type: Grant
    Filed: October 13, 2009
    Date of Patent: April 12, 2016
    Assignee: Cree, Inc.
    Inventors: Qingchun Zhang, Sei-Hyung Ryu, Anant K. Agarwal, Sarit Dhar
  • Patent number: 9269580
    Abstract: Embodiments of a semiconductor device having increased channel mobility and methods of manufacturing thereof are disclosed. In one embodiment, the semiconductor device includes a substrate including a channel region and a gate stack on the substrate over the channel region. The gate stack includes an alkaline earth metal. In one embodiment, the alkaline earth metal is Barium (Ba). In another embodiment, the alkaline earth metal is Strontium (Sr). The alkaline earth metal results in a substantial improvement of the channel mobility of the semiconductor device.
    Type: Grant
    Filed: September 9, 2011
    Date of Patent: February 23, 2016
    Assignee: Cree, Inc.
    Inventors: Sarit Dhar, Lin Cheng, Sei-Hyung Ryu, Anant Agarwal, John Williams Palmour, Jason Gurganus
  • Publication number: 20150325655
    Abstract: A metal-insulator-semiconductor field-effect transistor (MISFET) includes a SiC layer with source and drain regions of a first conductivity type spaced apart therein. A first gate insulation layer is on the SiC layer and has a net charge along an interface with the SiC layer that is the same polarity as majority carriers of the source region. A gate contact is on the first gate insulation layer over a channel region of the SiC layer between the source and drain regions. The net charge along the interface between the first gate insulation layer and the SiC layer may deplete majority carriers from an adjacent portion of the channel region between the source and drain regions in the SiC layer, which may increase the threshold voltage of the MISFET and/or increase the electron mobility therein.
    Type: Application
    Filed: August 14, 2014
    Publication date: November 12, 2015
    Inventors: Sarit DHAR, Sei-Hyung Ryu
  • Patent number: 9142662
    Abstract: A semiconductor device includes a drift layer having a first conductivity type, a well region in the drift layer having a second conductivity type opposite the first conductivity type, and a source region in the well region, The source region has the first conductivity type and defines a channel region in the well region. The source region includes a lateral source region adjacent the channel region and a plurality of source contact regions extending away from the lateral source region opposite the channel region. A body contact region having the second conductivity type is between at least two of the plurality of source contact regions and is in contact with the well region. A source ohmic contact overlaps at least one of the source contact regions and the body contact region. A minimum dimension of a source contact area of the semiconductor device is defined by an area of overlap between the source ohmic contact and the at least one source contact region.
    Type: Grant
    Filed: May 16, 2011
    Date of Patent: September 22, 2015
    Assignee: Cree, Inc.
    Inventors: Sei-Hyung Ryu, Doyle Craig Capell, Lin Cheng, Sarit Dhar, Charlotte Jonas, Anant Agarwal, John Palmour
  • Patent number: 9029945
    Abstract: A semiconductor device includes a drift layer having a first conductivity type, a well region in the drift layer having a second conductivity type opposite the first conductivity type, and a source region in the well region. The source region has the first conductivity type and defines a channel region in the well region. The source region includes a lateral source region adjacent the channel region and a plurality of source contact regions extending away from the lateral source region opposite the channel region. A body contact region having the second conductivity type is between at least two of the plurality of source contact regions and is in contact with the well region. A source ohmic contact overlaps at least one of the source contact regions and the body contact region. A minimum dimension of a source contact area of the semiconductor device is defined by an area of overlap between the source ohmic contact and the at least one source contact region.
    Type: Grant
    Filed: May 6, 2011
    Date of Patent: May 12, 2015
    Assignee: Cree, Inc.
    Inventors: Sei-Hyung Ryu, Doyle Craig Capell, Lin Cheng, Sarit Dhar, Charlotte Jonas, Anant Agarwal, John Palmour
  • Patent number: 8841682
    Abstract: A metal-insulator-semiconductor field-effect transistor (MISFET) includes a SiC layer with source and drain regions of a first conductivity type spaced apart therein. A first gate insulation layer is on the SiC layer and has a net charge along an interface with the SiC layer that is the same polarity as majority carriers of the source region. A gate contact is on the first gate insulation layer over a channel region of the SiC layer between the source and drain regions. The net charge along the interface between the first gate insulation layer and the SiC layer may deplete majority carriers from an adjacent portion of the channel region between the source and drain regions in the SiC layer, which may increase the threshold voltage of the MISFET and/or increase the electron mobility therein.
    Type: Grant
    Filed: August 27, 2009
    Date of Patent: September 23, 2014
    Assignee: Cree, Inc.
    Inventors: Sarit Dhar, Sei-Hyung Ryu
  • Publication number: 20130034941
    Abstract: Methods of forming a semiconductor structure include providing an insulation layer on a semiconductor layer and diffusing cesium ions into the insulation layer from a cesium ion source outside the insulation layer. A MOSFET including an insulation layer treated with cesium ions may exhibit increased inversion layer mobility.
    Type: Application
    Filed: August 3, 2011
    Publication date: February 7, 2013
    Inventors: Sarit Dhar, Sei-Hyung Ryu, Anant Agarwal, John Robert Williams
  • Publication number: 20120326163
    Abstract: Embodiments of a semiconductor device having increased channel mobility and methods of manufacturing thereof are disclosed. In one embodiment, the semiconductor device includes a substrate including a channel region and a gate stack on the substrate over the channel region. The gate stack includes an alkaline earth metal. In one embodiment, the alkaline earth metal is Barium (Ba). In another embodiment, the alkaline earth metal is Strontium (Sr). The alkaline earth metal results in a substantial improvement of the channel mobility of the semiconductor device.
    Type: Application
    Filed: September 9, 2011
    Publication date: December 27, 2012
    Applicant: CREE, INC.
    Inventors: Sarit Dhar, Lin Cheng, Sei-Hyung Ryu, Anant Agarwal, John Williams Palmour, Jason Gurganus
  • Publication number: 20120329216
    Abstract: Embodiments of a semiconductor device having increased channel mobility and methods of manufacturing thereof are disclosed. In one embodiment, the semiconductor device includes a substrate including a channel region and a gate stack on the substrate over the channel region. The gate stack includes an alkaline earth metal. In one embodiment, the alkaline earth metal is Barium (Ba). In another embodiment, the alkaline earth metal is Strontium (Sr). The alkaline earth metal results in a substantial improvement of the channel mobility of the semiconductor device.
    Type: Application
    Filed: September 9, 2011
    Publication date: December 27, 2012
    Applicant: CREE, INC.
    Inventors: Sarit Dhar, Lin Cheng, Sei-Hyung Ryu, Anant Agarwal, John Williams Palmour, Erik Maki, Jason Gurganus, Daniel Jenner Lichtenwalner
  • Publication number: 20120280270
    Abstract: A semiconductor device includes a drift layer having a first conductivity type, a well region in the drift layer having a second conductivity type opposite the first conductivity type, and a source region in the well region, The source region has the first conductivity type and defines a channel region in the well region. The source region includes a lateral source region adjacent the channel region and a plurality of source contact regions extending away from the lateral source region opposite the channel region. A body contact region having the second conductivity type is between at least two of the plurality of source contact regions and is in contact with the well region. A source ohmic contact overlaps at least one of the source contact regions and the body contact region. A minimum dimension of a source contact area of the semiconductor device is defined by an area of overlap between the source ohmic contact and the at least one source contact region.
    Type: Application
    Filed: May 16, 2011
    Publication date: November 8, 2012
    Inventors: Sei-Hyung Ryu, Doyle Craig Capell, Lin Cheng, Sarit Dhar, Charlotte Jonas, Anant Agarwal, John Palmour
  • Publication number: 20120280252
    Abstract: A semiconductor device includes a drift layer having a first conductivity type, a well region in the drift layer having a second conductivity type opposite the first conductivity type, and a source region in the well region, The source region has the first conductivity type and defines a channel region in the well region. The source region includes a lateral source region adjacent the channel region and a plurality of source contact regions extending away from the lateral source region opposite the channel region. A body contact region having the second conductivity type is between at least two of the plurality of source contact regions and is in contact with the well region. A source ohmic contact overlaps at least one of the source contact regions and the body contact region. A minimum dimension of a source contact area of the semiconductor device is defined by an area of overlap between the source ohmic contact and the at least one source contact region.
    Type: Application
    Filed: May 6, 2011
    Publication date: November 8, 2012
    Inventors: Sei-Hyung Ryu, Doyle Craig Capell, Lin Cheng, Sarit Dhar, Charlotte Jonas, Anant Agarwal, John Palmour
  • Publication number: 20120223330
    Abstract: Semiconductor devices having a high performance channel and method of fabrication thereof are disclosed. Preferably, the semiconductor devices are Metal-Oxide-Semiconductor (MOS) devices, and even more preferably the semiconductor devices are Silicon Carbide (SiC) MOS devices. In one embodiment, a semiconductor device includes a SiC substrate of a first conductivity type, a first well of a second conductivity type, a second well of the second conductivity type, and a surface diffused channel of the second conductivity type formed at the surface of semiconductor device between the first and second wells. A depth and doping concentration of the surface diffused channel are controlled to provide increased carrier mobility for the semiconductor device as compared to the same semiconductor device without the surface diffused channel region when in the on-state while retaining a turn-on, or threshold, voltage that provides normally-off behavior.
    Type: Application
    Filed: March 3, 2011
    Publication date: September 6, 2012
    Applicant: CREE, INC.
    Inventors: Sarit Dhar, Sei-Hyung Ryu, Lin Cheng, Anant Agarwal
  • Publication number: 20110147764
    Abstract: A metal-insulator-semiconductor field-effect transistor (MISFET) includes a semiconductor layer with source and drain regions of a first conductivity type spaced apart therein. A channel region of a first conductivity type extends between the source and drain regions. A gate contact is on the channel region. A dielectric channel depletion layer is between the gate contact and the channel region. The dielectric channel depletion layer provides a net charge having the same polarity as the first conductivity type charge carriers, and which may deplete the first conductivity type charge carriers from an adjacent portion of the channel region when no voltage is applied to the gate contact.
    Type: Application
    Filed: November 4, 2009
    Publication date: June 23, 2011
    Inventors: Sarit Dhar, Sei-Hyung Ryu, Veena Misra, Daniel J. Lichtenwalner
  • Publication number: 20110084284
    Abstract: A transistor may include a semiconductor drift layer of a first semiconductor material and a semiconductor channel layer on the semiconductor drift layer. The semiconductor channel layer may include a second semiconductor material different than the first semiconductor material. A semiconductor interconnection layer may be electrically coupled between the semiconductor drift layer and the semiconductor channel layer, and the semiconductor interconnection layer may include a third semiconductor material different than the first and second semiconductor materials. In addition, a control electrode may be provided on the semiconductor channel layer.
    Type: Application
    Filed: October 13, 2009
    Publication date: April 14, 2011
    Inventors: Qingchun Zhang, Sei-Hyung Ryu, Anant K. Agarwal, Sarit Dhar
  • Publication number: 20110049530
    Abstract: A metal-insulator-semiconductor field-effect transistor (MISFET) includes a SiC layer with source and drain regions of a first conductivity type spaced apart therein. A first gate insulation layer is on the SiC layer and has a net charge along an interface with the SiC layer that is the same polarity as majority carriers of the source region. A gate contact is on the first gate insulation layer over a channel region of the SiC layer between the source and drain regions. The net charge along the interface between the first gate insulation layer and the SiC layer may deplete majority carriers from an adjacent portion of the channel region between the source and drain regions in the SiC layer, which may increase the threshold voltage of the MISFET and/or increase the electron mobility therein.
    Type: Application
    Filed: August 27, 2009
    Publication date: March 3, 2011
    Inventors: Sarit Dhar, Sei-Hyung Ryu