Patents by Inventor William J. Schaff

William J. Schaff 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: 7993938
    Abstract: A method of forming a highly doped layer of AlGaN, is practiced by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1×1020 cm?3 at Al mole fractions up to 65% are obtained. These levels of doping application of n-type bulk, and n/p tunnel injection to short wavelength UV emitters. Some applications include light emitting diodes having wavelengths between approximately 254 and 290 nm for use in fluorescent light bulbs, hazardous materials detection, water purification and other decontamination environments. Lasers formed using the highly doped layers are useful in high-density storage applications or telecommunications applications. In yet a further embodiment, a transistor is formed utilizing the highly doped layer as a channel.
    Type: Grant
    Filed: January 27, 2009
    Date of Patent: August 9, 2011
    Assignee: Cornell Research Foundation, Inc.
    Inventors: William J. Schaff, Jeonghyun Hwang
  • Patent number: 7622322
    Abstract: A passivation layer of AlN is deposited on a GaN channel HFET using molecular beam epitaxy (MBE). Using MBE, many other surfaces may also be coated with AlN, including silicon devices, nitride devices, GaN based LEDs and lasers as well as other semiconductor systems. The deposition is performed at approximately 150° C. and uses alternating beams of aluminum and remote plasma RF nitrogen to produce an approximately 500 ? thick AlN layer.
    Type: Grant
    Filed: May 15, 2001
    Date of Patent: November 24, 2009
    Assignee: Cornell Research Foundation, Inc.
    Inventors: William J. Schaff, Jeonghyun Hwang, Bruce M. Green
  • Publication number: 20090227093
    Abstract: The growing surface of a material such as InGaN is exposed to a small diameter laser beam that is directed to controlled locations, such as by scanning mirrors. Material characteristics may be modified at the points of exposure. In one embodiment, mole fraction of selected material is reduced where laser exposure takes place. In one embodiment, the material is grown in a MBE or CVD chamber.
    Type: Application
    Filed: February 16, 2007
    Publication date: September 10, 2009
    Applicant: Cornell Research Foundation, Inc
    Inventors: William J. Schaff, Xiaodong Chen
  • Publication number: 20090165816
    Abstract: A method of forming a highly doped layer of AlGaN, is practiced by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1×1020 cm?3 at Al mole fractions up to 65% are obtained. These levels of doping application of n-type bulk, and n/p tunnel injection to short wavelength UV emitters. Some applications include light emitting diodes having wavelengths between approximately 254 and 290 nm for use in fluorescent light bulbs, hazardous materials detection, water purification and other decontamination environments. Lasers formed using the highly doped layers are useful in high-density storage applications or telecommunications applications. In yet a further embodiment, a transistor is formed utilizing the highly doped layer as a channel.
    Type: Application
    Filed: January 27, 2009
    Publication date: July 2, 2009
    Applicant: Cornell Research Foundation, Inc.
    Inventors: William J. Schaff, Jeonghyun Hwang
  • Patent number: 7485901
    Abstract: A wide bandgap semiconductor material is heavily doped to a degenerate level. Impurity densities approaching 1% of the volume of the semiconductor crystal are obtained to greatly increase conductivity. In one embodiment, a layer of AlGaN is formed on a wafer by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1×1020 cm?3 at Al mole fractions up to 65% are obtained.
    Type: Grant
    Filed: March 16, 2005
    Date of Patent: February 3, 2009
    Assignee: Cornell Research Foundation Inc.
    Inventors: William J. Schaff, Jeonghyun Hwang
  • Patent number: 7482191
    Abstract: A method of forming a highly doped layer of AlGaN, is practiced by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1×1020 cm?3 at Al mole fractions up to 65% are obtained. These levels of doping application of n-type bulk, and n/p tunnel injection to short wavelength UV emitters. Some applications include light emitting diodes having wavelengths between approximately 254 and 290 nm for use in fluorescent light bulbs, hazardous materials detection, water purification and other decontamination environments. Lasers formed using the highly doped layers are useful in high-density storage applications or telecommunications applications. In yet a further embodiment, a transistor is formed utilizing the highly doped layer as a channel.
    Type: Grant
    Filed: March 17, 2005
    Date of Patent: January 27, 2009
    Assignee: Cornell Research Foundation, Inc.
    Inventors: William J. Schaff, Jeonghyun Hwang
  • Patent number: 7217882
    Abstract: An alloy having a large band gap range is used in a multijunction solar cell to enhance utilization of the solar energy spectrum. In one embodiment, the alloy is In1?xGaxN having an energy bandgap range of approximately 0.7 eV to 3.4 eV, providing a good match to the solar energy spectrum. Multiple junctions having different bandgaps are stacked to form a solar cell. Each junction may have different bandgaps (realized by varying the alloy composition), and therefore be responsive to different parts of the spectrum. The junctions are stacked in such a manner that some bands of light pass through upper junctions to lower junctions that are responsive to such bands.
    Type: Grant
    Filed: May 27, 2003
    Date of Patent: May 15, 2007
    Assignees: Cornell Research Foundation, Inc., The Regents of the University of California
    Inventors: Wladyslaw Walukiewicz, Kin Man Yu, Junqiao Wu, William J. Schaff
  • Patent number: 6953740
    Abstract: A wide bandgap semiconductor material is heavily doped to a degenerate level. Impurity densities approaching 1% of the volume of the semiconductor crystal are obtained to greatly increase conductivity. In one embodiment, a layer of AlGaN is formed on a wafer by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1×1020 cm?3 at Al mole fractions up to 65% are obtained.
    Type: Grant
    Filed: May 15, 2002
    Date of Patent: October 11, 2005
    Assignee: Cornell Research Foundation, Inc.
    Inventors: William J. Schaff, Jeonghyun Hwang
  • Patent number: 6888170
    Abstract: A method of forming a highly doped layer of AlGaN, is practiced by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1×1020 cm?3 at Al mole fractions up to 65% are obtained. These levels of doping application of n-type bulk, and n/p tunnel injection to short wavelength UV emitters. Some applications include light emitting diodes having wavelengths between approximately 254 and 290 nm for use in fluorescent light bulbs, hazardous materials detection, water purification and other decontamination environments. Lasers formed using the highly doped layers are useful in high-density storage applications or telecommunications applications. In yet a further embodiment, a transistor is formed utilizing the highly doped layer as a channel.
    Type: Grant
    Filed: May 7, 2002
    Date of Patent: May 3, 2005
    Assignee: Cornell Research Foundation, Inc.
    Inventors: William J. Schaff, Jeonghyun Hwang
  • Publication number: 20040118451
    Abstract: An alloy having a large band gap range is used in a multijunction solar cell to enhance utilization of the solar energy spectrum. In one embodiment, the alloy is In1-xGaxN having an energy bandgap range of approximately 0.7 eV to 3.4 eV, providing a good match to the solar energy spectrum. Multiple junctions having different bandgaps are stacked to form a solar cell. Each junction may have different bandgaps (realized by varying the alloy composition), and therefore be responsive to different parts of the spectrum. The junctions are stacked in such a manner that some bands of light pass through upper junctions to lower junctions that are responsive to such bands.
    Type: Application
    Filed: May 27, 2003
    Publication date: June 24, 2004
    Inventors: Wladyslaw Walukiewicz, Kin Man Yu, Junqiao Wu, William J. Schaff
  • Publication number: 20030176003
    Abstract: A wide bandgap semiconductor material is heavily doped to a degenerate level. Impurity densities approaching 1% of the volume of the semiconductor crystal are obtained to greatly increase conductivity. In one embodiment, a layer of AlGaN is formed on a wafer by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1×1020 cm−3 at Al mole fractions up to 65% are obtained.
    Type: Application
    Filed: May 15, 2002
    Publication date: September 18, 2003
    Inventors: William J. Schaff, Jeonghyun Hwang
  • Publication number: 20030173578
    Abstract: A method of forming a highly doped layer of AlGaN, is practiced by first removing contaminants from a MBE machine. Wafers are then outgassed in the machine at very low pressures. A nitride is then formed on the wafer and an AlN layer is grown. The highly doped GaAlN layer is then formed having electron densities beyond 1×1020 cm−3 at Al mole fractions up to 65% are obtained. These levels of doping application of n-type bulk, and n/p tunnel injection to short wavelength UV emitters. Some applications include light emitting diodes having wavelengths between approximately 254 and 290 nm for use in fluorescent light bulbs, hazardous materials detection, water purification and other decontamination environments. Lasers formed using the highly doped layers are useful in high-density storage applications or telecommunications applications. In yet a further embodiment, a transistor is formed utilizing the highly doped layer as a channel.
    Type: Application
    Filed: May 7, 2002
    Publication date: September 18, 2003
    Inventors: William J. Schaff, Jeonghyun Hwang
  • Publication number: 20020137236
    Abstract: A passivation layer of AlN is deposited on a GaN channel HFET using molecular beam epitaxy (MBE). Using MBE, many other surfaces may also be coated with AlN, including silicon devices, nitride devices, GaN based LEDs and lasers as well as other semiconductor systems. The deposition is performed at approximately 150° C. and uses alternating beams of aluminum and remote plasma RF nitrogen to produce an approximately 500 Å thick AlN layer.
    Type: Application
    Filed: May 15, 2001
    Publication date: September 26, 2002
    Inventors: William J. Schaff, Jeonghyun Hwang, Bruce M. Green