Patents by Inventor Richard A. Stall

Richard A. Stall 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: 7863172
    Abstract: A gallium nitride based semiconductor Schottky diode fabricated from a n+ doped GaN layer having a thickness between one and six microns disposed on a sapphire substrate; an n? doped GaN layer having a thickness greater than one micron disposed on said n+ GaN layer patterned into a plurality of elongated fingers and a metal layer disposed on the n? doped GaN layer and forming a Schottky junction therewith. The layer thicknesses and the length and width of the elongated fingers are optimized to achieve a device with breakdown voltage of greater than 500 volts, current capacity in excess of one ampere, and a forward voltage of less than three volts.
    Type: Grant
    Filed: October 10, 2008
    Date of Patent: January 4, 2011
    Assignee: Power Integrations, Inc.
    Inventors: TingGang Zhu, Bryan S. Shelton, Marek K. Pabisz, Mark Gottfried, Linlin Liu, Milan Pophristic, Michael Murphy, Richard A. Stall
  • Publication number: 20090035925
    Abstract: A gallium nitride based semiconductor Schottky diode fabricated from a n+ doped GaN layer having a thickness between one and six microns disposed on a sapphire substrate; an n? doped GaN layer having a thickness greater than one micron disposed on said n+ GaN layer patterned into a plurality of elongated fingers and a metal layer disposed on the n? doped GaN layer and forming a Schottky junction therewith. The layer thicknesses and the length and width of the elongated fingers are optimized to achieve a device with breakdown voltage of greater than 500 volts, current capacity in excess of one ampere, and a forward voltage of less than three volts.
    Type: Application
    Filed: October 10, 2008
    Publication date: February 5, 2009
    Inventors: TingGang Zhu, Bryan S. Shelton, Marek K. Pabisz, Mark Gottfried, Linlin Liu, Milan Pophristic, Michael Murphy, Richard A. Stall
  • Patent number: 7436039
    Abstract: A gallium nitride based semiconductor Schottky diode fabricated from a n+ doped GaN layer having a thickness between one and six microns disposed on a sapphire substrate; an n? doped GaN layer having a thickness greater than one micron disposed on said n+ GaN layer patterned into a plurality of elongated fingers and a metal layer disposed on the n? doped GaN layer and forming a Schottky junction therewith. The layer thicknesses and the length and width of the elongated fingers are optimized to achieve a device with breakdown voltage of greater than 500 volts, current capacity in excess of one ampere, and a forward voltage of less than three volts.
    Type: Grant
    Filed: January 6, 2005
    Date of Patent: October 14, 2008
    Assignee: Velox Semiconductor Corporation
    Inventors: TingGang Zhu, Bryan S. Shelton, Marek K. Pabisz, Mark Gottfried, Linlin Liu, Milan Pophristic, Michael Murphy, Richard A. Stall
  • Patent number: 7253015
    Abstract: A repeatable and uniform low doped layer is formed using modulation doping by forming alternating sub-layers of doped and undoped nitride semiconductor material atop another layer. A Schottky diode is formed of such a low doped nitride semiconductor layer disposed atop a much more highly doped nitride semiconductor layer. The resulting device has both a low on-resistance when the device is forward biased and a high breakdown voltage when the device is reverse biased.
    Type: Grant
    Filed: February 17, 2004
    Date of Patent: August 7, 2007
    Assignee: Velox Semiconductor Corporation
    Inventors: Milan Pophristic, Michael Murphy, Richard A. Stall, Bryan S. Shelton, Linlin Liu, Alex D. Ceruzzi
  • Patent number: 7235139
    Abstract: A wafer carrier for growing wafers includes a plate having a first surface and a second surface, a plurality of openings extending from the first surface to the second surface of the plate, and a porous element disposed in each of the plurality of openings, each porous element being adapted to support one or more wafers. The wafer carrier also has a blind central opening extending from the second surface toward the first surface of the plate, and a plurality of shafts extending outwardly from the blind central opening. Each shaft has a first end in communication with the blind central opening and a second end in communication with one of the porous elements for providing fluid communication between the blind central opening and one of the porous elements. Suction is formed at a surface of each porous element by drawing vacuum through the blind central opening and the shafts.
    Type: Grant
    Filed: October 28, 2004
    Date of Patent: June 26, 2007
    Assignee: Veeco Instruments Inc.
    Inventors: Vadim Boguslavskiy, Alex Gurary, Richard A. Stall
  • Patent number: 7115896
    Abstract: A nitride semiconductor is grown on a silicon substrate by depositing a few mono-layers of aluminum to protect the silicon substrate from ammonia used during the growth process, and then forming a nucleation layer from aluminum nitride and a buffer structure including multiple superlattices of AlRGa(1-R)N semiconductors having different compositions and an intermediate layer of GaN or other Ga-rich nitride semiconductor. The resulting structure has superior crystal quality. The silicon substrate used in epitaxial growth is removed before completion of the device so as to provide superior electrical properties in devices such as high-electron mobility transistors.
    Type: Grant
    Filed: November 25, 2003
    Date of Patent: October 3, 2006
    Assignee: Emcore Corporation
    Inventors: Shiping Guo, David Gotthold, Milan Pophristic, Boris Peres, Ivan Eliashevich, Bryan S. Shelton, Alex D. Ceruzzi, Michael Murphy, Richard A. Stall
  • Patent number: 7084475
    Abstract: A lateral conduction Schottky diode includes multiple mesa regions upon which Schottky contacts are formed and which are at least separated by ohmic contacts to reduce the current path length and reduce current crowding in the Schottky contact, thereby reducing the forward resistance of a device. The multiple mesas may be isolated from one another and have sizes and shapes optimized for reducing the forward resistance. Alternatively, some of the mesas may be finger-shaped and intersect with a central mesa or a bridge mesa, and some or all of the ohmic contacts are interdigitated with the finger-shaped mesas. The dimensions of the finger-shaped mesas and the perimeter of the intersecting structure may be optimized to reduce the forward resistance. The Schottky diodes may be mounted to a submount in a flip chip arrangement that further reduces the forward voltage as well as improves power dissertation and reduces heat generation.
    Type: Grant
    Filed: February 17, 2004
    Date of Patent: August 1, 2006
    Assignee: Velox Semiconductor Corporation
    Inventors: Bryan S. Shelton, Linlin Liu, Alex D. Ceruzzi, Michael Murphy, Milan Pophristic, Boris Peres, Richard A. Stall, Xiang Gao, Ivan Eliashevich
  • Publication number: 20060154455
    Abstract: A nitride semiconductor is grown on a silicon substrate by depositing a few mono-layers of aluminum to protect the silicon substrate from ammonia used during the growth process, and then forming a nucleation layer from aluminum nitride and a buffer structure including multiple superlattices of AlRGa(1-R)N semiconductors having different compositions and an intermediate layer of GaN or other Ga-rich nitride semiconductor. The resulting structure has superior crystal quality. The silicon substrate used in epitaxial growth is removed before completion of the device so as to provide superior electrical properties in devices such as high-electron mobility transistors.
    Type: Application
    Filed: March 9, 2006
    Publication date: July 13, 2006
    Applicant: Emcore Corporation
    Inventors: Shiping Guo, David Gotthold, Milan Pophristic, Boris Peres, Ivan Eliashevich, Bryan Shelton, Alex Ceruzzi, Michael Murphy, Richard Stall
  • Publication number: 20060145283
    Abstract: A gallium nitride based semiconductor Schottky diode fabricated from a n+ doped GaN layer having a thickness between one and six microns disposed on a sapphire substrate; an n? doped GaN layer having a thickness greater than one micron disposed on said n+ GaN layer patterned into a plurality of elongated fingers and a metal layer disposed on the n? doped GaN layer and forming a Schottky junction therewith. The layer thicknesses and the length and width of the elongated fingers are optimized to achieve a device with breakdown voltage of greater than 500 volts, current capacity in excess of one ampere, and a forward voltage of less than three volts.
    Type: Application
    Filed: January 6, 2005
    Publication date: July 6, 2006
    Inventors: TingGang Zhu, Bryan Shelton, Marek Pabisz, Mark Gottfried, Linlin Liu, Milan Pophristic, Michael Murphy, Richard Stall
  • Publication number: 20050179107
    Abstract: A repeatable and uniform low doped layer is formed using modulation doping by forming alternating sub-layers of doped and undoped nitride semiconductor material atop another layer. A Schottky diode is formed of such a low doped nitride semiconductor layer disposed atop a much more highly doped nitride semiconductor layer. The resulting device has both a low on-resistance when the device is forward biased and a high breakdown voltage when the device is reverse biased.
    Type: Application
    Filed: February 17, 2004
    Publication date: August 18, 2005
    Applicant: Emcore Corporation
    Inventors: Milan Pophristic, Michael Murphy, Richard Stall, Bryan Shelton, Linlin Liu, Alex Ceruzzi
  • Publication number: 20050179104
    Abstract: A lateral conduction Schottky diode includes multiple mesa regions upon which Schottky contacts are formed and which are at least separated by ohmic contacts to reduce the current path length and reduce current crowding in the Schottky contact, thereby reducing the forward resistance of a device. The multiple mesas may be isolated from one another and have sizes and shapes optimized for reducing the forward resistance. Alternatively, some of the mesas may be finger-shaped and intersect with a central mesa or a bridge mesa, and some or all of the ohmic contacts are interdigitated with the finger-shaped mesas. The dimensions of the finger-shaped mesas and the perimeter of the intersecting structure may be optimized to reduce the forward resistance. The Schottky diodes may be mounted to a submount in a flip chip arrangement that further reduces the forward voltage as well as improves power dissertation and reduces heat generation.
    Type: Application
    Filed: February 17, 2004
    Publication date: August 18, 2005
    Applicant: Emcore Corporation
    Inventors: Bryan Shelton, Linlin Liu, Alex Ceruzzi, Michael Murphy, Milan Pophristic, Boris Peres, Richard Stall, Xiang Gao, Ivan Eliashevich
  • Publication number: 20050126496
    Abstract: A wafer carrier for growing wafers includes a plate having a first surface and a second surface, a plurality of openings extending from the first surface to the second surface of the plate, and a porous element disposed in each of the plurality of openings, each porous element being adapted to support one or more wafers. The wafer carrier also has a blind central opening extending from the second surface toward the first surface of the plate, and a plurality of shafts extending outwardly from the blind central opening. Each shaft has a first end in communication with the blind central opening and a second end in communication with one of the porous elements for providing fluid communication between the blind central opening and one of the porous elements. Suction is formed at a surface of each porous element by drawing vacuum through the blind central opening and the shafts.
    Type: Application
    Filed: October 28, 2004
    Publication date: June 16, 2005
    Inventors: Vadim Boguslavskiy, Alex Gurary, Richard Stall
  • Publication number: 20040119063
    Abstract: A nitride semiconductor is grown on a silicon substrate by depositing a few mono-layers of aluminum to protect the silicon substrate from ammonia used during the growth process, and then forming a nucleation layer from aluminum nitride and a buffer structure including multiple superlattices of AlRGa(1−R)N semiconductors having different compositions and an intermediate layer of GaN or other Ga-rich nitride semiconductor. The resulting structure has superior crystal quality. The silicon substrate used in epitaxial growth is removed before completion of the device so as to provide superior electrical properties in devices such as high-electron mobility transistors.
    Type: Application
    Filed: November 25, 2003
    Publication date: June 24, 2004
    Applicant: Emcore Corporation
    Inventors: Shiping Guo, David Gotthold, Milan Pophristic, Boris Peres, Ivan Eliashevich, Bryan S. Shelton, Alex D. Ceruzzi, Michael Murphy, Richard A. Stall
  • Patent number: 6197121
    Abstract: Reactors for growing epitaxial layers on substrates are disclosed including rotatable substrate carriers and injectors for injecting gases into the reactor towards the substrates on the carriers and including a gas separator for separately maintaining various gases between gas inlets and the injector. Various reactor embodiments are disclosed including removable gas separators, and particular injectors which include cooling channels, as well as flow restrictors mounted within the reactors to restrict the flow of the gases to the substrates from the injector, and heaters mounted within the rotatable shell holding the substrate carriers so that the heaters can be accessed and removed through a lid forming a wall of the reactor.
    Type: Grant
    Filed: June 30, 1999
    Date of Patent: March 6, 2001
    Assignee: Emcore Corporation
    Inventors: Alexander I. Gurary, Richard A. Stall, Robert F. Karlicek, Jr., Peter Zawadzki, Thomas Salagaj
  • Patent number: 6001183
    Abstract: A wafer carrier/susceptor combination for use in an epitaxial deposition process has a configuration which provides greater thermal conductivity between the susceptor and the wafer carrier in regions substantially underlying the wafers than in regions not underlying the wafers. This difference in thermal conductivity is produced by configuring the wafer carrier or susceptor so that the lower surface of the wafer carrier is disposed closer to the susceptor in regions substantially underlying the wafers than in at least some regions not underlying the wafers. By controlling the thermal conductivity so that it is greater in certain regions than in other regions, the temperature difference between the wafers and the surface of the wafer carrier can be reduced, and a more uniform temperature distribution across the surface of the wafer can be achieved. As a result, the combination may be used to deposit a more uniform coating across the entire surface of each wafer.
    Type: Grant
    Filed: September 30, 1996
    Date of Patent: December 14, 1999
    Assignee: Emcore Corporation
    Inventors: Alexander I. Gurary, Eric A. Armour, Douglas A. Collins, Richard A. Stall
  • Patent number: 5544618
    Abstract: An apparatus for depositing a coating on a substrate substantially eliminates the occurrence of oval defects by creating a heated tortuous path through which the source material vapors must travel before depositing on the substrate. In addition, shut-off valves for each of the source materials are positioned in the reaction chamber in close proximity to the substrate, thereby enabling layers of different compositions to be deposited with sharp transitions between adjacent layers. The apparatus may be used to efficiently coat large areas uniformly, and works equally well with either elemental or chemical source materials, or certain combinations of both. The features of the coating apparatus may be embodied in replacement source cells for retrofitting in conventional molecular beam and chemical beam epitaxy units.
    Type: Grant
    Filed: May 23, 1994
    Date of Patent: August 13, 1996
    Inventors: Richard A. Stall, Gary S. Tompa, Alexander Gurary, Craig R. Nelson
  • Patent number: 5336324
    Abstract: An apparatus for depositing a coating on a substrate substantially eliminates the occurrence of oval defects by creating a heated tortuous path through which the source material vapors must travel before depositing on the substrate. In addition, shut-off valves for each of the source materials are positioned in the reaction chamber in close proximity to the substrate, thereby enabling layers of different compositions to be deposited with sharp transitions between adjacent layers. The apparatus may be used to efficiently coat large areas uniformly, and works equally well with either elemental or chemical source materials, or certain combinations of both. The features of the coating apparatus may be embodied in replacement source cells for retrofitting in conventional molecular beam and chemical beam epitaxy units.
    Type: Grant
    Filed: December 4, 1991
    Date of Patent: August 9, 1994
    Assignee: Emcore Corporation
    Inventors: Richard A. Stall, Gary S. Tompa, Alexander Gurary, Craig R. Nelson
  • Patent number: 4969416
    Abstract: Substrates such as semiconductor wafers are treated with a gas by advancing the substrate along a path, preferably a circular path through the gas while maintaining a face of the substrate transverse, preferably oblique, to the path so that the gas contacts be exposed from the face of the substrate. Preferably, a plurality of substrates are treated simultaneously, and the substrates serve as vanes to impel the gas into rotational motion, thereby pumping the gas through the process chamber. Preferably, the substrates are carried on susceptors having generally planar faces, the susceptors also serving as vanes impelling the gas into rotational motion. The gas may be a depositing gas for forming epitaxial layers on the faces of the substrates, or an etching gas.
    Type: Grant
    Filed: February 27, 1990
    Date of Patent: November 13, 1990
    Assignee: Emcore, Inc.
    Inventors: Norman E. Schumaker, Richard A. Stall, Craig R. Nelson, Wilfried R. Wagner
  • Patent number: 4838983
    Abstract: Substrates such as semiconductor wafers are treated with a gas by advancing the substrate along a path, preferably a circular path through the gas while maintaining a face of the substrate transverse, preferably oblique, to the path so taht the gas contacts be exposed from the face of the substrate. Preferably, a plurality of substrates are treated simultaneously, and the substrates serve as vanes to impel the gas into rotational motion, thereby pumping the gas through the process chamber. Preferably, the substrates are carried on susceptors having generally planar faces, the susceptors also serving as vanes impelling the gas into rotational motion. The gas may be a depositing gas for forming epitaxial layers on the faces of the substrates, or an etching gas.
    Type: Grant
    Filed: March 18, 1988
    Date of Patent: June 13, 1989
    Assignee: Emcore, Inc.
    Inventors: Norman E. Schumaker, Richard A. Stall, Craig R. Nelson, Wilfried R. Wagner
  • Patent number: 4772356
    Abstract: Substrates such as semiconductor wafers are treated with a gas by advancing the substrate along a path, preferably a circular path through the gas while maintaining a face of the substrate transverse, preferably oblique, to the path so that the gas contacts be exposed from the face of the substrate. Preferably, a plurality of substrates are treated simultaneously, and the substrates serve as vanes to impel the gas into rotational motion, thereby pumping the gas through the process chamber. Preferably, the substrates are carried on susceptors having generally planar faces, the susceptors also serving as vanes impelling the gas into rotational motion. The gas may be a depositing gas for forming epitaxial layers on the faces of the substrates, or an etching gas.
    Type: Grant
    Filed: July 3, 1986
    Date of Patent: September 20, 1988
    Assignee: Emcore, Inc.
    Inventors: Norman E. Schumaker, Richard A. Stall, Craig R. Nelson, Wilfried R. Wagner