Patents Assigned to AXT, Inc.
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Publication number: 20100176336Abstract: 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: ApplicationFiled: September 29, 2009Publication date: July 15, 2010Applicant: AXT, INC.Inventors: Tan Kaixie, Gu Yan, Wang Yuanli
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Publication number: 20100116196Abstract: 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: ApplicationFiled: September 5, 2009Publication date: May 13, 2010Applicant: AXT, INC.Inventor: Weiguo Liu
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Publication number: 20100001288Abstract: 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: ApplicationFiled: July 20, 2009Publication date: January 7, 2010Applicant: AXT, Inc.Inventors: Weiguo Liu, Morris S. Young, M. Hani Badawi
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Patent number: 7566641Abstract: 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: GrantFiled: May 9, 2007Date of Patent: July 28, 2009Assignee: AXT, Inc.Inventors: Weiguo Liu, Morris S. Young, M. Hani Badawi
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Publication number: 20090179015Abstract: 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: ApplicationFiled: January 15, 2008Publication date: July 16, 2009Applicants: AXT, INC., GSI Technology, Inc.Inventors: Xiaodong Zhao, Yingjie Geng
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Publication number: 20060183329Abstract: 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: ApplicationFiled: March 2, 2004Publication date: August 17, 2006Applicant: AXT, Inc.Inventors: Charles Leung, David Zhang, Morris Young
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Patent number: 6896729Abstract: 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: GrantFiled: July 3, 2002Date of Patent: May 24, 2005Assignee: AXT, Inc.Inventors: Xiao Gordon Liu, Wei Guo Liu
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Patent number: 6650018Abstract: 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: GrantFiled: May 24, 2002Date of Patent: November 18, 2003Assignee: AXT, Inc.Inventors: Yongsheng Zhao, William W. So, Kevin Y. Ma, Chyi S. Chern, Heng Liu, Eugene J. Ruddy
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Patent number: 6643304Abstract: 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: GrantFiled: July 26, 2000Date of Patent: November 4, 2003Assignee: AXT, Inc.Inventors: John Chen, Bingwen Liang, Robert Shih
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Publication number: 20030172870Abstract: 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: ApplicationFiled: March 14, 2002Publication date: September 18, 2003Applicant: AXT, Inc.Inventors: Xiao Gordon Liu, Weiguo Liu
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Patent number: 6580096Abstract: 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: GrantFiled: June 13, 2002Date of Patent: June 17, 2003Assignee: AXT, Inc.Inventors: John Chen, Bingwen Liang, Robert Shih
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Publication number: 20030010994Abstract: 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: ApplicationFiled: July 15, 2002Publication date: January 16, 2003Applicant: AXT, Inc.Inventors: John Chen, Bingwen Liang, Robert Shih
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Patent number: 6495867Abstract: 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: GrantFiled: July 26, 2000Date of Patent: December 17, 2002Assignee: AXT, Inc.Inventors: Changhua Chen, James Dong, Heng Liu
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Publication number: 20020175337Abstract: 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: ApplicationFiled: July 8, 2002Publication date: November 28, 2002Applicant: AXT, Inc.Inventors: Changhua Chen, James Dong, Heng Liu
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Patent number: 6459098Abstract: 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: GrantFiled: July 26, 2000Date of Patent: October 1, 2002Assignee: AXT, Inc.Inventors: John Chen, Bingwen Liang, Robert Shih
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Patent number: 6420736Abstract: 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: GrantFiled: July 26, 2000Date of Patent: July 16, 2002Assignee: AXT, Inc.Inventors: John Chen, Bingwen Liang, Robert Shih