Patents Assigned to AXT, Inc.
  • Publication number: 20100176336
    Abstract: Chemical polishing solutions and methods are disclosed for the chemical polishing of GaAs wafers. An exemplary chemical polishing solution consistent with the innovations herein may comprise dichloroisocyanurate, sulfonate, acid pyrophosphate, bicarbonate and carbonate. An exemplary chemical polishing method may comprise polishing a wafer in a chemical polishing apparatus in the presence of such a chemical polishing solution. Chemical polishing solutions and methods herein make it possible, for example, to improve wafer quality, decrease costs, and/or reduce environmental pollution.
    Type: Application
    Filed: September 29, 2009
    Publication date: July 15, 2010
    Applicant: AXT, INC.
    Inventors: Tan Kaixie, Gu Yan, Wang Yuanli
  • Publication number: 20100116196
    Abstract: Systems, methods, and substrates directed to growth of monocrystalline germanium (Ge) crystals are disclosed. In one exemplary implementation, there is provided a method for growing a monocrystalline germanium (Ge) crystal. Moreover, the method may include loading first raw Ge material into a crucible, loading second raw Ge material into a container for supplementing the Ge melt material, sealing the crucible and the container in an ampoule, placing the ampoule with the crucible into a crystal growth furnace, as well as melting the first and second raw Ge material and controlling the crystallizing temperature gradient of the melt to reproducibly provide monocrystalline germanium ingots with improved/desired characteristics.
    Type: Application
    Filed: September 5, 2009
    Publication date: May 13, 2010
    Applicant: AXT, INC.
    Inventor: Weiguo Liu
  • Publication number: 20100001288
    Abstract: A method for manufacturing wafers using a low EPD crystal growth process and a wafer annealing process is provided that results in GaAs/InGaP wafers that provide higher device yields from the wafer.
    Type: Application
    Filed: July 20, 2009
    Publication date: January 7, 2010
    Applicant: AXT, Inc.
    Inventors: Weiguo Liu, Morris S. Young, M. Hani Badawi
  • Patent number: 7566641
    Abstract: A method for manufacturing wafers using a low EPD crystal growth process and a wafer annealing process is provided that results in GaAs/InGaP wafers that provide higher device yields from the wafer.
    Type: Grant
    Filed: May 9, 2007
    Date of Patent: July 28, 2009
    Assignee: AXT, Inc.
    Inventors: Weiguo Liu, Morris S. Young, M. Hani Badawi
  • Publication number: 20090179015
    Abstract: A system and method for adjustable laser mark depth is provided. In one embodiment, the system is used in Nd—YAG laser marker for wafer processing in the semiconductor industry, with smart control of the mark depth and expanded work range between the deep mark and the light mark.
    Type: Application
    Filed: January 15, 2008
    Publication date: July 16, 2009
    Applicants: AXT, INC., GSI Technology, Inc.
    Inventors: Xiaodong Zhao, Yingjie Geng
  • Publication number: 20060183329
    Abstract: An apparatus and method of treating multiple wafers to reduce the density of impurities as well as to improve the uniformity of substrate electrical characteristics without any thermal stress. The wafers are chemically treated, and heat treated in a sealed reaction tube under arsenic overpressure with a controlled thermal profile to heat the wafers. The thermal profile controls temperature of different zones inside of a furnace containing the sealed reaction tube. Impurities of the wafers are dissolved, and are out-diffused from the inner portions to the outer portions of the wafers.
    Type: Application
    Filed: March 2, 2004
    Publication date: August 17, 2006
    Applicant: AXT, Inc.
    Inventors: Charles Leung, David Zhang, Morris Young
  • Patent number: 6896729
    Abstract: Group III-V, II-VI and related monocrystalline compounds are grown with a rigid support of a sealed ampoule, carbon doping and resistivity control, and thermal gradient control in a crystal growth furnace. A support cylinder provides structural support for the combined sealed ampoule crucible assembly, while low-density insulating material inside the support cylinder deters convection and conduction heating. Radiation channels penetrating the low-density material provide pathways for radiation heating into and out of the seed well and transition regions of the crystal growth crucible. A hollow core in the insulation material directly beneath the seed well provides cooling in the center of the growing crystal, which enables uniform, level growth of the crystal ingot and a flat crystal-melt interface which results in crystal wafers with uniform electrical properties.
    Type: Grant
    Filed: July 3, 2002
    Date of Patent: May 24, 2005
    Assignee: AXT, Inc.
    Inventors: Xiao Gordon Liu, Wei Guo Liu
  • Patent number: 6650018
    Abstract: A high power, high luminous flux light emitting diode (LED) comprises a substrate, a light-emitting structure, a first electrode and a second electrode. The LED has a top surface layout design in which the first electrode has a number of legs extending in one direction, and the second electrode has a number of legs extending in the opposite direction. At least portions of the legs of the first electrode are interspersed with and spaced apart from portions of the legs of the second electrode. This provides a configuration that enhances current spreading along the length of the legs of both electrodes.
    Type: Grant
    Filed: May 24, 2002
    Date of Patent: November 18, 2003
    Assignee: AXT, Inc.
    Inventors: Yongsheng Zhao, William W. So, Kevin Y. Ma, Chyi S. Chern, Heng Liu, Eugene J. Ruddy
  • Patent number: 6643304
    Abstract: A Gallium Nitride based Light Emitting Diode (LED) includes both a transparent substrate and a window for exiting light generated by the LED. Useful amounts of light may be utilized at the face of the window or at the face of the transparent substrate. An external optical reflector is formed directly on the external face of the LED which is not currently being used to exit useful light. If light from the window is being utilized, a Distributed Bragg Reflector (DBR) is formed directly on the “backside” of the substrate. However, if light through the substrate is being utilized, a Distributed Bragg Reflector is formed directly on the light emitting portion of the window.
    Type: Grant
    Filed: July 26, 2000
    Date of Patent: November 4, 2003
    Assignee: AXT, Inc.
    Inventors: John Chen, Bingwen Liang, Robert Shih
  • Publication number: 20030172870
    Abstract: An apparatus for producing large diameter monocrystalline Group III-V, II-VI compounds that have reduced crystal defect density, improved crystal growth yield, and improved bulk material characteristics. The apparatus comprises a crucible or boat, an ampoule that contains the crucible or boat, a heating unit disposed about the ampoule, and a liner disposed between the heating unit and the ampoule. The liner is preferably composed of a quartz material. When the liner and the ampoule are made of the same material, such as quartz, the thermal expansion coefficients of the liner and ampoule are the same, which significantly increases the lifetime of the liner and the single-crystal yield.
    Type: Application
    Filed: March 14, 2002
    Publication date: September 18, 2003
    Applicant: AXT, Inc.
    Inventors: Xiao Gordon Liu, Weiguo Liu
  • Patent number: 6580096
    Abstract: A light-emitting diode (LED) constructed of AlGaInP compounds includes a multi-layer window having, in the order of formation, a lightly doped first layer formed of p doped GaP; a low impedance second layer formed of p GaAs; an amorphous conducting layer formed of Indium Tin Oxide (ITO), and a titanium/gold contact. In one embodiment, the contact forms ohmic connections with the second and third layers; and a Schottky diode connection with the first layer. In a second embodiment, the contact forms an ohmic connection with the third layer; and is insulated from direct contact with the first layer.
    Type: Grant
    Filed: June 13, 2002
    Date of Patent: June 17, 2003
    Assignee: AXT, Inc.
    Inventors: John Chen, Bingwen Liang, Robert Shih
  • Publication number: 20030010994
    Abstract: A window structure for Gallium Nitride based Light Emitting Diode comprises: an Mg+ doped P window layer of a GaN compound; a thin semitransparent metal contact layer; an amorphous current spreading layer formed on the contact layer. The contact layer is formed of NiOx\Au; and the current spreading layer is formed of Indium Tin Oxide. The P electrode of the diode comprises a titanium adhesion layer which forms an ohmic connection with the current spreading layer and a Shottky diode connection with the Mg+ doped window layer.
    Type: Application
    Filed: July 15, 2002
    Publication date: January 16, 2003
    Applicant: AXT, Inc.
    Inventors: John Chen, Bingwen Liang, Robert Shih
  • Patent number: 6495867
    Abstract: A GaN based three layer buffer on a sapphire substrate provides a template for growth of a high quality I GaN layer as a substitute substrate for growth of a Nitride based LED.
    Type: Grant
    Filed: July 26, 2000
    Date of Patent: December 17, 2002
    Assignee: AXT, Inc.
    Inventors: Changhua Chen, James Dong, Heng Liu
  • Publication number: 20020175337
    Abstract: A GaN based three layer buffer on a sapphire substrate provides a template for growth of a high quality I GaN layer as a substitute substrate for growth of a Nitride based LED.
    Type: Application
    Filed: July 8, 2002
    Publication date: November 28, 2002
    Applicant: AXT, Inc.
    Inventors: Changhua Chen, James Dong, Heng Liu
  • Patent number: 6459098
    Abstract: A Light Emitting Diode (LED) constructed of AlGaInP compounds includes a multi layer window which improves the efficiency of the diode. The window, in the order of formation, includes a lightly doped first layer formed of p doped GaP; a low impedance second layer formed of p GaAs; an amorphous conducting layer formed of Indium Tin Oxide (ITO), and a titanium\gold contact. In one embodiment, the contact forms ohmic connections with the second and third layers; and a Shottky diode connection with first layer. In a second embodiment, the contact forms an ohmic connection with the third layer; and is insulated from direct contact with the first layer.
    Type: Grant
    Filed: July 26, 2000
    Date of Patent: October 1, 2002
    Assignee: AXT, Inc.
    Inventors: John Chen, Bingwen Liang, Robert Shih
  • Patent number: 6420736
    Abstract: A window structure for a gallium nitride (GaN)-based light emitting diode (LED) includes a Mg+ doped p window layer of a GaN compound; a thin, semi-transparent metal contact layer; and an amorphous current spreading layer formed on the contact layer. The contact layer is formed of NiOx/Au and the current spreading layer is formed of Indium Tin Oxide. The p electrode of the diode includes a titanium adhesion layer which forms an ohmic connection with the current spreading layer and a Schottky diode connection with the Mg+ doped window layer.
    Type: Grant
    Filed: July 26, 2000
    Date of Patent: July 16, 2002
    Assignee: AXT, Inc.
    Inventors: John Chen, Bingwen Liang, Robert Shih