Patents by Inventor Leo J. Schowalter

Leo J. Schowalter 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).

  • PHOTON EXTRACTION FROM NITRIDE ULTRAVIOLET LIGHT-EMITTING DEVICES
    Publication number: 20160181487
    Abstract: In various embodiments, a rigid lens is attached to a light-emitting semiconductor die via a layer of encapsulant having a thickness insufficient to prevent propagation of thermal expansion mismatch-induced strain between the rigid lens and the semiconductor die.
    Type: Application
    Filed: January 14, 2015
    Publication date: June 23, 2016
    Inventors: Leo J. Schowalter, Jianfeng Chen, James R. Grandusky
  • Pseudomorphic electronic and optoelectronic devices having planar contacts
    Patent number: 9299880
    Abstract: In various embodiments, light-emitting devices incorporate smooth contact layers and polarization doping (i.e., underlying layers substantially free of dopant impurities) and exhibit high photon extraction efficiencies.
    Type: Grant
    Filed: March 13, 2014
    Date of Patent: March 29, 2016
    Assignee: Crystal IS, Inc.
    Inventors: James R. Grandusky, Leo J. Schowalter, Muhammad Jamil, Mark C. Mendrick, Shawn R. Gibb
  • PHOTON EXTRACTION FROM ULTRAVIOLET LIGHT-EMITTING DEVICES
    Publication number: 20160027975
    Abstract: In various embodiments, a layer of organic encapsulant is provided over a surface of an ultraviolet (UV) light-emitting semiconductor die, and at least a portion of the encapsulant is exposed to UV light to convert at least some of said portion of the encapsulant into non-stoichiometric silica material. The non-stoichiometric silica material includes silicon, oxygen, and carbon, and a carbon content of the non-stoichiometric silica material is greater than 1 ppm and less than 40 atomic percent.
    Type: Application
    Filed: July 23, 2015
    Publication date: January 28, 2016
    Inventors: Ken Kitamura, Masato Toita, Hironori Ishii, Yuting Wang, Leo J. Schowalter, Jianfeng Chen, James R. Grandusky
  • DEFECT REDUCTION IN SEEDED ALUMINUM NITRIDE CRYSTAL GROWTH
    Publication number: 20150275393
    Abstract: Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density?100 cm?2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.
    Type: Application
    Filed: April 13, 2015
    Publication date: October 1, 2015
    Inventors: Robert T. Bondokov, Leo J. Schowalter, Kenneth Morgan, Glen A. Slack, Shailaja P. Rao, Shawn Robert Gibb
  • METHODS OF FORMING PLANAR CONTACTS TO PSEUDOMORPHIC ELECTRONIC AND OPTOELECTRONIC DEVICES
    Publication number: 20150280057
    Abstract: In various embodiments, smooth contact layers are formed on polarization-doped light-emitting devices to enable high photon extraction efficiencies.
    Type: Application
    Filed: March 13, 2014
    Publication date: October 1, 2015
    Inventors: James R. Grandusky, Leo J. Schowalter, Muhammad Jamil, Mark C. Mendrick, Shawn R. Gibb
  • GROWTH OF LARGE ALUMINUM NITRIDE SINGLE CRYSTALS WITH THERMAL-GRADIENT CONTROL
    Publication number: 20150218728
    Abstract: In various embodiments, non-zero thermal gradients are formed within a growth chamber both substantially parallel and substantially perpendicular to the growth direction during formation of semiconductor crystals, where the ratio of the two thermal gradients (parallel to perpendicular) is less than 10, by, e.g., arrangement of thermal shields outside of the growth chamber.
    Type: Application
    Filed: April 15, 2015
    Publication date: August 6, 2015
    Inventors: Robert T. Bondokov, Shailaja P. Rao, Shawn R. Gibb, Leo J. Schowalter
  • ALUMINUM NITRIDE BULK CRYSTALS HAVING HIGH TRANSPARENCY TO ULTRAVIOLET LIGHT AND METHODS OF FORMING THEM
    Publication number: 20150218729
    Abstract: In various embodiments, methods of forming single-crystal AlN include providing a substantially undoped polycrystalline AlN ceramic having an oxygen concentration less than approximately 100 ppm, forming a single-crystal bulk AlN crystal by a sublimation-recondensation process at a temperature greater than approximately 2000° C., and cooling the bulk AlN crystal to a first temperature between approximately 1500° C. and approximately 1800° C. at a first rate less than approximately 250° C./hour.
    Type: Application
    Filed: April 16, 2015
    Publication date: August 6, 2015
    Inventors: Sandra B. Schujman, Shailaja P. Rao, Robert T. Bondokov, Kenneth E. Morgan, Glen A. Slack, Leo J. Schowalter
  • Aluminum nitride bulk crystals having high transparency to ultraviolet light and methods of forming them
    Patent number: 9034103
    Abstract: In various embodiments, methods of forming single-crystal AlN include providing a substantially undoped polycrystalline AlN ceramic having an oxygen concentration less than approximately 100 ppm, forming a single-crystal bulk AlN crystal by a sublimation-recondensation process at a temperature greater than approximately 2000° C., and cooling the bulk AlN crystal to a first temperature between approximately 1500° C. and approximately 1800° C. at a first rate less than approximately 250° C./hour.
    Type: Grant
    Filed: June 30, 2010
    Date of Patent: May 19, 2015
    Assignee: CRYSTAL IS, INC.
    Inventors: Sandra B. Schujman, Shailaja P. Rao, Robert T. Bondokov, Kenneth E. Morgan, Glen A. Slack, Leo J. Schowalter
  • Growth of large aluminum nitride single crystals with thermal-gradient control
    Patent number: 9028612
    Abstract: In various embodiments, non-zero thermal gradients are formed within a growth chamber both substantially parallel and substantially perpendicular to the growth direction during formation of semiconductor crystals, where the ratio of the two thermal gradients (parallel to perpendicular) is less than 10, by, e.g., arrangement of thermal shields outside of the growth chamber.
    Type: Grant
    Filed: June 30, 2011
    Date of Patent: May 12, 2015
    Assignee: Crystal IS, Inc.
    Inventors: Robert T. Bondokov, Shailaja P. Rao, Shawn Robert Gibb, Leo J. Schowalter
  • Photon extraction from nitride ultraviolet light-emitting devices
    Patent number: 8962359
    Abstract: In various embodiments, a rigid lens is attached to a light-emitting semiconductor die via a layer of encapsulant having a thickness insufficient to prevent propagation of thermal expansion mismatch-induced strain between the rigid lens and the semiconductor die.
    Type: Grant
    Filed: July 19, 2012
    Date of Patent: February 24, 2015
    Assignee: Crystal IS, Inc.
    Inventors: Leo J. Schowalter, Jianfeng Chen, James R. Grandusky
  • DEFECT REDUCTION IN SEEDED ALUMINUM NITRIDE CRYSTAL GROWTH
    Publication number: 20150020731
    Abstract: Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density?100 cm?2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.
    Type: Application
    Filed: August 13, 2014
    Publication date: January 22, 2015
    Inventors: Robert T. Bondokov, Kenneth E. Morgan, Leo J. Schowalter, Glen A. Stack
  • DEFECT REDUCTION IN SEEDED ALUMINUM NITRIDE CRYSTAL GROWTH
    Publication number: 20150013592
    Abstract: Bulk single crystal of aluminum nitride (AlN) having an areal planar defect density ?100 cm?2. Methods for growing single crystal aluminum nitride include melting an aluminum foil to uniformly wet a foundation with a layer of aluminum, the foundation forming a portion of an AlN seed holder, for an AlN seed to be used for the AlN growth. The holder may consist essentially of a substantially impervious backing plate.
    Type: Application
    Filed: August 13, 2014
    Publication date: January 15, 2015
    Inventors: Robert T. Bondokov, Kenneth E. Morgan, Leo J. Schowalter, Glen A. Slack
  • PSEUDOMORPHIC ELECTRONIC AND OPTOELECTRONIC DEVICES HAVING PLANAR CONTACTS
    Publication number: 20140264263
    Abstract: In various embodiments, light-emitting devices incorporate smooth contact layers and polarization doping (i.e., underlying layers substantially free of dopant impurities) and exhibit high photon extraction efficiencies.
    Type: Application
    Filed: March 13, 2014
    Publication date: September 18, 2014
    Inventors: James R. Grandusky, Leo J. Schowalter, Muhammad Jamil, Mark C. Mendrick, Shawn R. Gibb
  • DOPED ALUMINUM NITRIDE CRYSTALS AND METHODS OF MAKING THEM
    Publication number: 20140231725
    Abstract: Fabrication of doped AlN crystals and/or AlGaN epitaxial layers with high conductivity and mobility is accomplished by, for example, forming mixed crystals including a plurality of impurity species and electrically activating at least a portion of the crystal.
    Type: Application
    Filed: March 26, 2014
    Publication date: August 21, 2014
    Inventors: Glen A. Slack, Leo J. Schowalter
  • PHOTON EXTRACTION FROM NITRIDE ULTRAVIOLET LIGHT-EMITTING DEVICES
    Publication number: 20140203311
    Abstract: In various embodiments, a rigid lens is attached to a light-emitting semiconductor die via a layer of encapsulant having a thickness insufficient to prevent propagation of thermal expansion mismatch-induced strain between the rigid lens and the semiconductor die.
    Type: Application
    Filed: July 19, 2012
    Publication date: July 24, 2014
    Applicant: Crystal IS, Inc.
    Inventors: Leo J. Schowalter, Jianfeng Chen, James R. Grandusky
  • Doped aluminum nitride crystals and methods of making them
    Patent number: 8747552
    Abstract: Fabrication of doped AlN crystals and/or AlGaN epitaxial layers with high conductivity and mobility is accomplished by, for example, forming mixed crystals including a plurality of impurity species and electrically activating at least a portion of the crystal.
    Type: Grant
    Filed: December 18, 2009
    Date of Patent: June 10, 2014
    Assignee: Crystal IS, Inc.
    Inventors: Glen A. Slack, Leo J. Schowalter
  • LARGE ALUMINUM NITRIDE CRYSTALS WITH REDUCED DEFECTS AND METHODS OF MAKING THEM
    Publication number: 20140093671
    Abstract: Reducing the microvoid (MV) density in AlN ameliorates numerous problems related to cracking during crystal growth, etch pit generation during the polishing, reduction of the optical transparency in an AlN wafer, and, possibly, growth pit formation during epitaxial growth of AlN and/or AlGaN. This facilitates practical crystal production strategies and the formation of large, bulk AlN crystals with low defect densities—e.g., a dislocation density below 104 cm?2 and an inclusion density below 104 cm?3 and/or a MV density below 104cm?3.
    Type: Application
    Filed: October 11, 2013
    Publication date: April 3, 2014
    Inventors: Robert Bondokov, Kenneth E. Morgan, Glen A. Slack, Leo J. Schowalter
  • Large aluminum nitride crystals with reduced defects and methods of making them
    Patent number: 8580035
    Abstract: Reducing the microvoid (MV) density in AlN ameliorates numerous problems related to cracking during crystal growth, etch pit generation during the polishing, reduction of the optical transparency in an AlN wafer, and, possibly, growth pit formation during epitaxial growth of AlN and/or AlGaN. This facilitates practical crystal production strategies and the formation of large, bulk AlN crystals with low defect densities—e.g., a dislocation density below 104 cm?2 and an inclusion density below 104 cm?3 and/or a MV density below 104 cm?3.
    Type: Grant
    Filed: December 6, 2012
    Date of Patent: November 12, 2013
    Assignee: Crystal IS, Inc.
    Inventors: Robert Bondokov, Kenneth E. Morgan, Glen A. Slack, Leo J. Schowalter
  • Method and apparatus for producing large, single-crystals of aluminum nitride
    Patent number: 8545629
    Abstract: Bulk single crystals of AlN having a diameter greater than about 25 mm and dislocation densities of about 10,000 cm?2 or less and high-quality AlN substrates having surfaces of any desired crystallographic orientation fabricated from these bulk crystals.
    Type: Grant
    Filed: May 9, 2006
    Date of Patent: October 1, 2013
    Assignee: Crystal IS, Inc.
    Inventors: Leo J. Schowalter, Glen A. Slack, J. Carlos Rojo, Robert T. Bondokov, Kenneth E. Morgan, Joseph A. Smart
  • Large aluminum nitride crystals with reduced defects and methods of making them
    Patent number: 8349077
    Abstract: Reducing the microvoid (MV) density in AlN ameliorates numerous problems related to cracking during crystal growth, etch pit generation during the polishing, reduction of the optical transparency in an AlN wafer, and, possibly, growth pit formation during epitaxial growth of AlN and/or AlGaN. This facilitates practical crystal production strategies and the formation of large, bulk AlN crystals with low defect densities—e.g., a dislocation density below 104 cm?2 and an inclusion density below 104 cm?3 and/or a MV density below 104 cm?3.
    Type: Grant
    Filed: November 28, 2006
    Date of Patent: January 8, 2013
    Assignee: Crystal IS, Inc.
    Inventors: Robert T. Bondokov, Kenneth Morgan, Glen A. Slack, Leo J. Schowalter