Patents by Inventor Michael Krames

Michael Krames 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).

  • Publication number: 20060091404
    Abstract: A III-nitride light emitting layer in a semiconductor light emitting device has a graded composition. The composition of the light emitting layer may be graded such that the change in the composition of a first element is at least 0.2% per angstrom of light emitting layer. Grading in the light emitting layer may reduce problems associated with polarization fields in the light emitting layer. The light emitting layer may be, for example InxGa1-xN, AlxGa1-xN, or InxAlyGa1-x-yN.
    Type: Application
    Filed: October 29, 2004
    Publication date: May 4, 2006
    Inventors: Yu-Chen Shen, Michael Krames, Nathan Gardner
  • Publication number: 20060011937
    Abstract: In a III-nitride light emitting device, a ternary or quaternary light emitting layer is configured to control the degree of phase separation. In some embodiments, the difference between the InN composition at any point in the light emitting layer and the average InN composition in the light emitting layer is less than 20%. In some embodiments, control of phase separation is accomplished by controlling the ratio of the lattice constant in a relaxed, free standing layer having the same composition as the light emitting layer to the lattice constant in a base region. For example, the ratio may be between about 1 and about 1.01.
    Type: Application
    Filed: September 14, 2005
    Publication date: January 19, 2006
    Inventors: Werner Goetz, Michael Krames, Anneli Munkholm
  • Publication number: 20060014310
    Abstract: A semiconductor light emitting device includes an n-type region, a p-type region, and light emitting region disposed between the n- and p-type regions. The n-type, p-type, and light emitting regions form a cavity having a top surface and a bottom surface. Both the top surface and the bottom surface of the cavity may have a rough surface. For example, the surface may have a plurality of peaks separated by a plurality of valleys. In some embodiments, the thickness of the cavity is kept constant by incorporating an etch-stop layer into the device, then thinning the layers of the device by a process that terminates on the etch-stop layer.
    Type: Application
    Filed: September 14, 2005
    Publication date: January 19, 2006
    Inventors: John Epler, Michael Krames, Jonathan Wierer
  • Publication number: 20060011935
    Abstract: A method for designing semiconductor light emitting devices is disclosed wherein the side surfaces (surfaces not parallel to the epitaxial layers) are formed at preferred angles relative to vertical (normal to the plane of the light-emitting active layer) to improve light extraction efficiency and increase total light output efficiency. Device designs are chosen to improve efficiency without resorting to excessive active area-yield loss due to shaping. As such, these designs are suitable for low-cost, high-volume manufacturing of semiconductor light-emitting devices with improved characteristics.
    Type: Application
    Filed: September 19, 2005
    Publication date: January 19, 2006
    Inventors: Michael Krames, Fred Kish, Tun Tan
  • Publication number: 20050269582
    Abstract: A semiconductor light emitting device comprising a light emitting layer disposed between an n-type region and a p-type region is combined with a ceramic layer which is disposed in a path of light emitted by the light emitting layer. The ceramic layer is composed of or includes a wavelength converting material such as a phosphor. Luminescent ceramic layers according to embodiments of the invention may be more robust and less sensitive to temperature than prior art phosphor layers. In addition, luminescent ceramics may exhibit less scattering and may therefore increase the conversion efficiency over prior art phosphor layers.
    Type: Application
    Filed: June 3, 2004
    Publication date: December 8, 2005
    Inventors: Gerd Mueller, Regina Mueller-Mach, Michael Krames, Peter Schmidt, Hans-Helmut Bechtel, Joerg Meyer, Jan de Graaf, Theo Kop
  • Publication number: 20050236641
    Abstract: In a III-nitride light emitting device, a ternary or quaternary light emitting layer is configured to control the degree of phase separation. In some embodiments, the difference between the InN composition at any point in the light emitting layer and the average InN composition in the light emitting layer is less than 20%. In some embodiments, control of phase separation is accomplished by controlling the ratio of the lattice constant in a relaxed, free standing layer having the same composition as the light emitting layer to the lattice constant in a base region. For example, the ratio may be between about 1 and about 1.01.
    Type: Application
    Filed: April 21, 2004
    Publication date: October 27, 2005
    Inventors: Werner Goetz, Michael Krames, Anneli Munkholm
  • Publication number: 20050224826
    Abstract: A light emitting device includes a light emitting diode (LED), a concentrator element, such as a compound parabolic concentrator, and a wavelength converting material, such as a phosphor. The concentrator element receives light from the LED and emits the light from an exit surface, which is smaller than the entrance surface. The wavelength converting material is, e.g., disposed over the exit surface. The radiance of the light emitting diode is preserved or increased despite the isotropic re-emitted light by the wavelength converting material. In one embodiment, the polarized light from a polarized LED is provided to a polarized optical system, such as a microdisplay. In another embodiment, the orthogonally polarized light from two polarized LEDs is combined, e.g., via a polarizing beamsplitter, and is provided to non-polarized optical system, such as a microdisplay. If desired, a concentrator element may be disposed between the beamsplitter and the microdisplay.
    Type: Application
    Filed: March 19, 2004
    Publication date: October 13, 2005
    Applicant: Lumileds Lighting, U.S., LLC
    Inventors: Matthijs Keuper, Michael Krames, Gerd Mueller
  • Publication number: 20050205883
    Abstract: A photonic crystal structure is formed in an n-type region of a III-nitride semiconductor structure including an active region sandwiched between an n-type region and a p-type region. A reflector is formed on a surface of the p-type region opposite the active region. In some embodiments, the growth substrate on which the n-type region, active region, and p-type region are grown is removed, in order to facilitate forming the photonic crystal in an an-type region of the device, and to facilitate forming the reflector on a surface of the p-type region underlying the photonic crystal. The photonic crystal and reflector form a resonant cavity, which may allow control of light emitted by the active region.
    Type: Application
    Filed: March 19, 2004
    Publication date: September 22, 2005
    Inventors: Jonathan Wierer, Michael Krames, John Epler
  • Publication number: 20050205884
    Abstract: A semiconductor light emitting device includes an in-plane active region that emits linearly-polarized light. An in-plane active region may include, for example, a {11{overscore (2)}0} or {10{overscore (1)}0} InGaN light emitting layer. In some embodiments, a polarizer oriented to pass light of a polarization of a majority of light emitted by the active region serves as a contact. In some embodiments, two active regions emitting the same or different colored light are separated by a polarizer oriented to pass light of a polarization of a majority of light emitted by the bottom active region, and to reflect light of a polarization of a majority of light emitted by the top active region. In some embodiments, a polarizer reflects light scattered by a wavelength converting layer.
    Type: Application
    Filed: March 19, 2004
    Publication date: September 22, 2005
    Inventors: Jarnes Kim, John Epler, Nathan Gardner, Michael Krames, Jonathan Wierer
  • Publication number: 20050082545
    Abstract: A photonic crystal structure is formed in an n-type layer of a III-nitride light emitting device. In some embodiments, the photonic crystal n-type layer is formed on a tunnel junction. The device includes a first layer of first conductivity type, a first layer of second conductivity type, and an active region separating the first layer of first conductivity type from the first layer of second conductivity type. The tunnel junction includes a second layer of first conductivity type and a second layer of second conductivity type and separates the first layer of first conductivity type from a third layer of first conductivity type. A photonic crystal structure is formed in the third layer of first conductivity type.
    Type: Application
    Filed: October 21, 2003
    Publication date: April 21, 2005
    Inventors: Jonathan Wierer, Michael Krames, Mihail Sigalas
  • Publication number: 20050032257
    Abstract: A method of bonding a transparent optical element to a light emitting device having a stack of layers including semiconductor layers comprising an active region is provided. The method includes elevating a temperature of the optical element and the stack and applying a pressure to press the optical element and the stack together. In one embodiment, the method also includes disposing a layer of a transparent bonding material between the stack and the optical element. The bonding method can be applied to a premade optical element or to a block of optical element material which is later formed or shaped into an optical element such as a lens or an optical concentrator.
    Type: Application
    Filed: September 10, 2004
    Publication date: February 10, 2005
    Inventors: Michael Camras, Michael Krames, Wayne Snyder, Frank Steranka, Robert Taber, John Uebbing, Douglas Pocius, Troy Trottier, Christopher Lowery, Gerd Mueller, Regina Mueller-Mach, Gloria Hofler
  • Publication number: 20050023549
    Abstract: A III-nitride device includes a first n-type layer, a first p-type layer, and an active region separating the first p-type layer and the first n-type layer. The device may include a second n-type layer and a tunnel junction separating the first and second n-type layers. First and second contacts are electrically connected to the first and second n-type layers. The first and second contacts are formed from the same material, a material with a reflectivity to light emitted by the active region greater than 75%. The device may include a textured layer disposed between the second n-type layer and the second contact or formed on a surface of a growth substrate opposite the device layers.
    Type: Application
    Filed: August 1, 2003
    Publication date: February 3, 2005
    Inventors: Nathan Gardner, Jonathan Wierer, Gerd Mueller, Michael Krames