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).
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Patent number: 7993938Abstract: 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: GrantFiled: January 27, 2009Date of Patent: August 9, 2011Assignee: Cornell Research Foundation, Inc.Inventors: William J. Schaff, Jeonghyun Hwang
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Patent number: 7622322Abstract: 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: GrantFiled: May 15, 2001Date of Patent: November 24, 2009Assignee: Cornell Research Foundation, Inc.Inventors: William J. Schaff, Jeonghyun Hwang, Bruce M. Green
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Publication number: 20090227093Abstract: 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: ApplicationFiled: February 16, 2007Publication date: September 10, 2009Applicant: Cornell Research Foundation, IncInventors: William J. Schaff, Xiaodong Chen
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Publication number: 20090165816Abstract: 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: ApplicationFiled: January 27, 2009Publication date: July 2, 2009Applicant: Cornell Research Foundation, Inc.Inventors: William J. Schaff, Jeonghyun Hwang
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Patent number: 7485901Abstract: 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: GrantFiled: March 16, 2005Date of Patent: February 3, 2009Assignee: Cornell Research Foundation Inc.Inventors: William J. Schaff, Jeonghyun Hwang
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Patent number: 7482191Abstract: 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: GrantFiled: March 17, 2005Date of Patent: January 27, 2009Assignee: Cornell Research Foundation, Inc.Inventors: William J. Schaff, Jeonghyun Hwang
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Patent number: 7217882Abstract: 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: GrantFiled: May 27, 2003Date of Patent: May 15, 2007Assignees: Cornell Research Foundation, Inc., The Regents of the University of CaliforniaInventors: Wladyslaw Walukiewicz, Kin Man Yu, Junqiao Wu, William J. Schaff
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Patent number: 6953740Abstract: 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: GrantFiled: May 15, 2002Date of Patent: October 11, 2005Assignee: Cornell Research Foundation, Inc.Inventors: William J. Schaff, Jeonghyun Hwang
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Patent number: 6888170Abstract: 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: GrantFiled: May 7, 2002Date of Patent: May 3, 2005Assignee: Cornell Research Foundation, Inc.Inventors: William J. Schaff, Jeonghyun Hwang
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Publication number: 20040118451Abstract: 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: ApplicationFiled: May 27, 2003Publication date: June 24, 2004Inventors: Wladyslaw Walukiewicz, Kin Man Yu, Junqiao Wu, William J. Schaff
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Publication number: 20030176003Abstract: 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: ApplicationFiled: May 15, 2002Publication date: September 18, 2003Inventors: William J. Schaff, Jeonghyun Hwang
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Publication number: 20030173578Abstract: 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: ApplicationFiled: May 7, 2002Publication date: September 18, 2003Inventors: William J. Schaff, Jeonghyun Hwang
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Publication number: 20020137236Abstract: 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: ApplicationFiled: May 15, 2001Publication date: September 26, 2002Inventors: William J. Schaff, Jeonghyun Hwang, Bruce M. Green