Patents by Inventor Ulrich Kretzer

Ulrich Kretzer 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: 11965266
    Abstract: A device (1?, 1?, 1??) for manufacturing III-V-crystals and wafers (14) manufactured therefrom, which are free of residual stress and dislocations, from melt (16) of a raw material optionally supplemented by lattice hardening dopants comprises a crucible (2?, 2?, 2??) for receiving the melt (16) having a first section (4?, 4?) including a first cross-sectional area and a second section (6?) for receiving a seed crystal (12) and having a second cross-sectional area, wherein the second cross-sectional area is smaller than the first cross-sectional area and the first and second sections are connected with each other directly or via third section (8, 8?) which tapers from the first section towards the second section, in order to allow a crystallization starting from the seed crystal (12) within the directed temperature field (T) into the solidifying melt.
    Type: Grant
    Filed: June 3, 2020
    Date of Patent: April 23, 2024
    Assignee: Freiberger Compound Materials GMBH
    Inventors: Stefan Eichler, Michael Rosch, Dmitry Suptel, Ulrich Kretzer, Berndt Weinert
  • Publication number: 20220106702
    Abstract: A device (1?, 1?, 1??) for manufacturing III-V-crystals and wafers (14) manufactured therefrom, which are free of residual stress and dislocations, from melt (16) of a raw material optionally supplemented by lattice hardening dopants comprises a crucible (2?, 2?, 2??) for receiving the melt (16) having a first section (4?, 4?) including a first cross-sectional area and a second section (6?) for receiving a seed crystal (12) and having a second cross-sectional area, wherein the second cross-sectional area is smaller than the first cross-sectional area and the first and second sections are connected with each other directly or via third section (8, 8?) which tapers from the first section towards the second section, in order to allow a crystallization starting from the seed crystal (12) within the directed temperature field (T) into the solidifying melt.
    Type: Application
    Filed: June 3, 2020
    Publication date: April 7, 2022
    Inventors: Stefan EICHLER, Michael ROSCH, Dmitry SUPTEL, Ulrich KRETZER, Berndt WEINERT
  • Patent number: 8815392
    Abstract: A process is disclosed for producing a doped gallium arsenide single crystal by melting a gallium arsenide starting material and subsequently solidifying the gallium arsenide melt, wherein the gallium arsenide melt contains an excess of gallium relative to the stoichiometric composition, and wherein it is provided for a boron concentration of at least 5×1017 cm?3 in the melt or in the obtained crystal. The thus obtained crystal is characterized by a unique combination of low dislocation density, high conductivity and yet excellent, very low optic absorption, particularly in the range of the near infrared.
    Type: Grant
    Filed: November 8, 2012
    Date of Patent: August 26, 2014
    Assignee: Freiberger Compound Materials GmbH
    Inventors: Ulrich Kretzer, Frank Börner, Stefan Eichler, Frieder Kropfgans
  • Patent number: 8771560
    Abstract: In a process for manufacturing doped semiconductor single crystal comprises solidifying in a crucible, the amount of dopant is added into the semiconductor melt after the beginning of the crystal growth onto the seed crystal, or after at least partial solidification of the semiconductor single crystal in a conical or tapered portion of the crucible. Dopant may be partially added in advance into the crucible, with the remainder added into the semiconductor melt as described. Type III-V semiconductor single crystals or wafers having a diameter of at least about 100 mm, can be prepared having an electrical conductivity of at least about 250 Siemens/cm, and/or an electric resistivity of at most about 4×10?3 ?cm, and/or a significantly improved ratio of hall mobility to charge carrier concentration.
    Type: Grant
    Filed: February 20, 2008
    Date of Patent: July 8, 2014
    Assignee: Freiberger Compound Materials GmbH
    Inventors: Ulrich Kretzer, Stefan Eichler, Thomas Bünger
  • Patent number: 8329295
    Abstract: A process is disclosed for producing a doped gallium arsenide single crystal by melting a gallium arsenide starting material and subsequently solidifying the gallium arsenide melt, wherein the gallium arsenide melt contains an excess of gallium relative to the stoichiometric composition, and wherein it is provided for a boron concentration of at least 5×1017 cm?3 in the melt or in the obtained crystal. The thus obtained crystal is characterized by a unique combination of low dislocation density, high conductivity and yet excellent, very low optic absorption, particularly in the range of the near infrared.
    Type: Grant
    Filed: July 9, 2009
    Date of Patent: December 11, 2012
    Assignee: Freiberger Compound Materials GmbH
    Inventors: Ulrich Kretzer, Frank Börner, Stefan Eichler, Frieder Kropfgans
  • Publication number: 20100006777
    Abstract: A process is disclosed for producing a doped gallium arsenide single crystal by melting a gallium arsenide starting material and subsequently solidifying the gallium arsenide melt, wherein the gallium arsenide melt contains an excess of gallium relative to the stoichiometric composition, and wherein it is provided for a boron concentration of at least 5×1017 cm?3 in the melt or in the obtained crystal. The thus obtained crystal is characterized by a unique combination of low dislocation density, high conductivity and yet excellent, very low optic absorption, particularly in the range of the near infrared.
    Type: Application
    Filed: July 9, 2009
    Publication date: January 14, 2010
    Inventors: Ulrich KRETZER, Frank Borner, Stefan Eichler, Frieder Kropfgans
  • Publication number: 20080203362
    Abstract: In a process for manufacturing doped semiconductor single crystal comprises solidifying in a crucible, the amount of dopant is added into the semiconductor melt after the beginning of the crystal growth onto the seed crystal, or after at least partial solidification of the semiconductor single crystal in a conical or tapered portion of the crucible. Dopant may be partially added in advance into the crucible, with the remainder added into the semiconductor melt as described. Type III-V semiconductor single crystals or wafers having a diameter of at least about 100 mm, can be prepared having an electrical conductivity of at least about 250 Siemens/cm, and/or an electric resistivity of at most about 4×10?3 ?cm, and/or a significantly improved ratio of hall mobility to charge carrier concentration.
    Type: Application
    Filed: February 20, 2008
    Publication date: August 28, 2008
    Inventors: Ulrich Kretzer, Stefan Eichler, Thomas Bunger
  • Patent number: 7410540
    Abstract: In a process for manufacturing doped semiconductor single crystal comprises solidifying in a crucible, the amount of dopant is added into the semiconductor melt after the beginning of the crystal growth onto the seed crystal, or after at least partial solidification of the semiconductor single crystal in a conical or tapered portion of the crucible. Dopant may be partially added in advance into the crucible, with the remainder added into the semiconductor melt as described. Type III-V semiconductor single crystals or wafers having a diameter of at least about 100 mm, can be prepared having an electrical conductivity of at least about 250 Siemens/cm, and/or an electric resistivity of at most about 4×10?3 ?cm, and/or a significantly improved ratio of hall mobility to charge carrier concentration.
    Type: Grant
    Filed: June 30, 2006
    Date of Patent: August 12, 2008
    Assignee: Freiberger Compound Materials GmbH
    Inventors: Ulrich Kretzer, Stefan Eichler, Thomas Bünger
  • Publication number: 20070012238
    Abstract: In a process for manufacturing doped semiconductor single crystal comprises solidifying in a crucible, the amount of dopant is added into the semiconductor melt after the beginning of the crystal growth onto the seed crystal, or after at least partial solidification of the semiconductor single crystal in a conical or tapered portion of the crucible. Dopant may be partially added in advance into the crucible, with the remainder added into the semiconductor melt as described. Type III-V semiconductor single crystals or wafers having a diameter of at least about 100 mm, can be prepared having an electrical conductivity of at least about 250 Siemens/cm, and/or an electric resistivity of at most about 4×10?3 ?cm, and/or a significantly improved ratio of hall mobility to charge carrier concentration.
    Type: Application
    Filed: June 30, 2006
    Publication date: January 18, 2007
    Inventors: Ulrich Kretzer, Stefan Eichler, Thomas Bunger