Patents by Inventor Katsuhiro Imai

Katsuhiro Imai 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: 20170260644
    Abstract: A crystal growth apparatus includes a pressure-resistant vessel; a plurality of support tables arranged inside the pressure-resistant vessel; inner vessels each placed over the support tables, respectively; growth vessels contained the inner vessels, respectively; a heating means for heating the growth vessels; and a central rotating shaft connected to the support tables. The central rotating shaft is distant from central axes of the inner vessels, respectively. A seed crystal, a raw material of the Group 13 element and a flux are charged in each of the growth vessels, and the growth vessels are heated to form a melt and a nitrogen-containing gas is supplied to the melt to grow a crystal of a nitride of said Group 13 element while the central rotating shaft is rotated.
    Type: Application
    Filed: May 25, 2017
    Publication date: September 14, 2017
    Applicant: NGK INSULATORS, LTD.
    Inventors: Takashi Yoshino, Katsuhiro Imai, Takanao Shimodaira, Takashi Wada
  • Publication number: 20170211797
    Abstract: It is provided a heat discharge structure for a light source device emitting a semiconductor laser. The structure fixes the light source device and discharges heat. The structure includes a film of a nitride of a group 13 element having a first main face, a second main face and an outer side end face. The structure further includes a portion for containing the light source device. The portion has a through hole opening at the first main face and the second main face, and a fixing face for fixing the light source device. The fixing face faces the through hole and contacts the light source device.
    Type: Application
    Filed: January 24, 2017
    Publication date: July 27, 2017
    Applicant: NGK INSULATORS, LTD.
    Inventors: Masahiko Namerikawa, Takashi Yoshino, Katsuhiro Imai, Yoshitaka Kuraoka
  • Patent number: 9677192
    Abstract: A group 13 nitride crystal substrate according to the present invention is produced by growing a group 13 nitride crystal on a seed-crystal substrate by a flux method, wherein a content of inclusions in the group 13 nitride crystal grown in a region of the seed-crystal substrate except for a circumferential portion of the seed-crystal substrate, the region having an area fraction of 70% relative to an entire area of the seed-crystal substrate, is 10% or less, preferably 2% or less.
    Type: Grant
    Filed: July 15, 2011
    Date of Patent: June 13, 2017
    Assignee: NGK Insulators, Ltd.
    Inventors: Takanao Shimodaira, Katsuhiro Imai, Makoto Iwai, Takayuki Hirao
  • Patent number: 9663871
    Abstract: A crystal production method according to the present invention includes a film formation and crystallization step of spraying a raw material powder containing a raw material component to form a film containing the raw material component on a seed substrate containing a single crystal at a predetermined single crystallization temperature at which single crystallization of the raw material component occurs, and crystallizing the film containing the raw material while maintaining the single crystallization temperature. In the film formation and crystallization step, preferably, the single crystallization temperature is 900° C. or higher. Furthermore, in the film formation and crystallization step, preferably, the raw material powder and the seed substrate are each a nitride or an oxide.
    Type: Grant
    Filed: April 19, 2013
    Date of Patent: May 30, 2017
    Assignee: NGK Insulators, Ltd.
    Inventors: Nobuyuki Kobayashi, Kazuki Maeda, Koichi Kondo, Tsutomu Nanataki, Katsuhiro Imai, Jun Yoshikawa
  • Patent number: 9653649
    Abstract: The maximum value of peak intensities of cathode luminescence of a wavelength corresponding to a band gap of gallium nitride and in a measured visual field of 0.1 mm×0.1 mm is 140 percent or higher of an average value of the peak intensities of the cathode luminescence, provided that the peak intensities of the cathode luminescence are measured on a surface of the gallium nitride substrate.
    Type: Grant
    Filed: October 27, 2015
    Date of Patent: May 16, 2017
    Assignee: NGK INSULATORS, LTD.
    Inventors: Makoto Iwai, Masahiro Sakai, Katsuhiro Imai, Yoshitaka Kuraoka
  • Patent number: 9640720
    Abstract: Provided is a surface light-emitting device comprising a substrate composed of an oriented polycrystalline zinc oxide sintered body in a plate shape, a light emitting functional layer provided on the substrate, and an electrode provided on the light emitting functional layer. According to the present invention, a surface light-emitting device having high luminous efficiency can be inexpensively provided.
    Type: Grant
    Filed: June 12, 2015
    Date of Patent: May 2, 2017
    Assignee: NGK Insulators, Ltd.
    Inventors: Morimichi Watanabe, Katsuhiro Imai, Jun Yoshikawa, Tsutomu Nanataki, Takashi Yoshino, Yukihisa Takeuchi
  • Patent number: 9627568
    Abstract: Disclosed is a photovoltaic device comprising a substrate composed of an oriented polycrystalline zinc oxide sintered body in a plate shape, a photovoltaic layer provided on the substrate, and an electrode provided on the photovoltaic layer. According to the present invention, a photovoltaic device having high photoelectric conversion efficiency can be inexpensively provided.
    Type: Grant
    Filed: October 22, 2015
    Date of Patent: April 18, 2017
    Assignee: NGK Insulators, Ltd.
    Inventors: Mikiya Ichimura, Jun Yoshikawa, Katsuhiro Imai
  • Patent number: 9548418
    Abstract: Provided is a self-supporting gallium nitride substrate useful as an alternative material for a gallium nitride single crystal substrate, which is inexpensive and also suitable for having a large area. This substrate is composed of a plate composed of gallium nitride-based single crystal grains, wherein the plate has a single crystal structure in the approximately normal direction. This substrate can be manufactured by a method comprising providing an oriented polycrystalline sintered body; forming a seed crystal layer composed of gallium nitride on the sintered body so that the seed crystal layer has crystal orientation mostly in conformity with the crystal orientation of the sintered body; forming a layer with a thickness of 20 ?m or greater composed of gallium nitride-based crystals on the seed crystal layer so that the layer has crystal orientation mostly in conformity with crystal orientation of the seed crystal layer; and removing the sintered body.
    Type: Grant
    Filed: February 5, 2016
    Date of Patent: January 17, 2017
    Assignee: NGK Insulators, Ltd.
    Inventors: Morimichi Watanabe, Jun Yoshikawa, Tsutomu Nanataki, Katsuhiro Imai, Tomohiko Sugiyama, Takashi Yoshino, Yukihisa Takeuchi, Kei Sato
  • Publication number: 20160355945
    Abstract: It is used a crucible containing a flux and a source material, a reaction vessel containing the crucible, an intermediate vessel containing the reaction vessel, and a pressure vessel containing the intermediate vessel and used to fill a gas comprising at least a nitrogen atom. When the flux and the source material are melted by heating to grow the nitride crystal, a vapor of an organic compound is provided in a space outside of the reaction vessel and inside of the intermediate vessel.
    Type: Application
    Filed: August 17, 2016
    Publication date: December 8, 2016
    Applicant: NGK INSULATORS, LTD.
    Inventors: Katsuhiro Imai, Makoto Iwai, Masahiro Sakai, Takanao Shimodaira, Shuhei Higashihara, Takayuki Hirao
  • Publication number: 20160300980
    Abstract: In a substrate having a gallium nitride layer, surface damage after surface treatment of the gallium nitride layer is reduced and quality of a functional device formed thereon is improved. A substrate 4 having at least a gallium nitride layer 4 is provided. A plasma etching system equipped with an inductively coupled plasma generating system is used and a fluorine-based gas is introduced at a standardized direct current bias potential of ?10V/cm2 or higher to subject a surface 3a of the gallium nitride layer to dry etching treatment.
    Type: Application
    Filed: June 23, 2016
    Publication date: October 13, 2016
    Applicant: NGK INSULATORS, LTD.
    Inventors: Shuhei Higashihara, Makoto Iwai, Katsuhiro Imai
  • Publication number: 20160293800
    Abstract: Provided is a light emitting device composite substrate suitable for manufacturing large-area light emitting devices at low cost. The light emitting device composite substrate comprises a substrate composed of an oriented polycrystalline alumina sintered body, and a light emitting functional layer formed on the substrate and having two or more layers composed of semiconductor single crystal grains, wherein each of the two or more layers has a single crystal structure in a direction approximately normal to the substrate.
    Type: Application
    Filed: June 15, 2016
    Publication date: October 6, 2016
    Applicant: NGK INSULATORS, LTD.
    Inventors: Morimichi WATANABE, Jun YOSHIKAWA, Tsutomu NANATAKI, Katsuhiro IMAI, Tomohiko SUGIYAMA, Takashi YOSHINO, Yukihisa TAKEUCHI, Kei SATO
  • Publication number: 20160172541
    Abstract: Provided is a self-supporting gallium nitride substrate useful as an alternative material for a gallium nitride single crystal substrate, which is inexpensive and also suitable for having a large area. This substrate is composed of a plate composed of gallium nitride-based single crystal grains, wherein the plate has a single crystal structure in the approximately normal direction. This substrate can be manufactured by a method comprising providing an oriented polycrystalline sintered body; forming a seed crystal layer composed of gallium nitride on the sintered body so that the seed crystal layer has crystal orientation mostly in conformity with the crystal orientation of the sintered body; forming a layer with a thickness of 20 ?m or greater composed of gallium nitride-based crystals on the seed crystal layer so that the layer has crystal orientation mostly in conformity with crystal orientation of the seed crystal layer; and removing the sintered body.
    Type: Application
    Filed: February 5, 2016
    Publication date: June 16, 2016
    Inventors: Morimichi WATANABE, Jun YOSHIKAWA, Tsutomu NANATAKI, Katsuhiro IMAI, Tomohiko SUGIYAMA, Takashi YOSHINO, Yukihisa TAKEUCHI, Kei SATO
  • Publication number: 20160168749
    Abstract: It is produced a crystal of a nitride of a group 13 element in a melt including the group 13 element and a flux including at least an alkali metal under atmosphere comprising a nitrogen-containing gas. An amount of carbon is made 0.005 to 0.018 atomic percent, provided that 100 atomic percent is assigned to a total amount of said flux, said group 13 element and carbon in said melt.
    Type: Application
    Filed: February 18, 2016
    Publication date: June 16, 2016
    Applicant: NGK INSULATORS, LTD.
    Inventors: Takayuki Hirao, Shuhei Higashihara, Katsuhiro Imai
  • Patent number: 9327994
    Abstract: The present invention provides a zinc oxide powder that enables a high degree of orientation, and highly uniform dispersion of an additive substance, to be simultaneously achieved in a green body or a sintered body. The zinc oxide powder of the present invention comprises a plurality of plate-like zinc oxide particles and has a volume-based D50 average particle diameter of 1 to 5 ?m and a specific surface area of 1 to 5 m2/g. The zinc oxide powder has a degree of orientation of the (002) plane of 40% or greater when two-dimensionally arrayed into a monolayer on a substrate.
    Type: Grant
    Filed: December 15, 2014
    Date of Patent: May 3, 2016
    Assignee: NGK Insulators, Ltd.
    Inventors: Jun Yoshikawa, Katsuhiro Imai, Koichi Kondo
  • Patent number: 9318307
    Abstract: Provided is a zinc oxide sputtering target, which can effectively suppress the occurrence of break or crack in the target during sputtering to enable production of a zinc oxide transparent conductive film with high productivity. The zinc oxide sputtering target is composed of a zinc oxide sintered body comprising zinc oxide crystal grains, wherein the zinc oxide sputtering target has a sputter surface having a (100) crystal orientation degree of 50% or more.
    Type: Grant
    Filed: June 16, 2014
    Date of Patent: April 19, 2016
    Assignee: NGK Insulators, Ltd.
    Inventors: Jun Yoshikawa, Katsuhiro Imai, Koichi Kondo
  • Patent number: 9312446
    Abstract: Provided is a self-supporting gallium nitride substrate useful as an alternative material for a gallium nitride single crystal substrate, which is inexpensive and also suitable for having a large area. This substrate is composed of a plate composed of gallium nitride-based single crystal grains, wherein the plate has a single crystal structure in the approximately normal direction. This substrate can be manufactured by a method comprising providing an oriented polycrystalline sintered body; forming a seed crystal layer composed of gallium nitride on the sintered body so that the seed crystal layer has crystal orientation mostly in conformity with the crystal orientation of the sintered body; forming a layer with a thickness of 20 ?m or greater composed of gallium nitride-based crystals on the seed crystal layer so that the layer has crystal orientation mostly in conformity with crystal orientation of the seed crystal layer; and removing the sintered body.
    Type: Grant
    Filed: September 29, 2014
    Date of Patent: April 12, 2016
    Assignee: NGK Insulators, Ltd.
    Inventors: Morimichi Watanabe, Jun Yoshikawa, Tsutomu Nanataki, Katsuhiro Imai, Tomohiko Sugiyama, Takashi Yoshino, Yukihisa Takeuchi, Kei Sato
  • Patent number: 9290861
    Abstract: Regarding a base substrate, a plurality of steps are formed stepwise on the principal surface (c-face). Each step has a height difference of 10 to 40 ?m, and an edge is formed parallel to an a-face of a hexagonal crystal of GaN. Meanwhile, the terrace width of each step is set at a predetermined width. The predetermined width is set in such a way that after a GaN crystal is grown on the principal surface of the base substrate, the principal surface is covered up with grain boundaries when the grown GaN crystal is observed from the surface side. The plurality of steps can be formed through, for example, dry etching, sand blasting, lasing, and dicing.
    Type: Grant
    Filed: October 15, 2010
    Date of Patent: March 22, 2016
    Assignee: NGK INSULATORS, LTD.
    Inventors: Takayuki Hirao, Takanao Shimodaira, Katsuhiro Imai
  • Patent number: 9287453
    Abstract: In the case that a functional layer, made of a nitride of a group 13 element, is formed on a composite substrate including a sapphire body and a gallium nitride crystal layer disposed over the sapphire body, the deviation of the function is prevented. The composite substrate 4 includes a sapphire body 1A and a gallium nitride crystal layer 3 disposed over the sapphire body. Aa warpage of the composite substrate is in a range of not less than +40 ?m and not more than +80 ?m per 5.08 cm in length.
    Type: Grant
    Filed: September 14, 2015
    Date of Patent: March 15, 2016
    Assignee: NGK INSULATORS, LTD.
    Inventors: Makoto Iwai, Katsuhiro Imai, Masahiro Sakai
  • Publication number: 20160049554
    Abstract: The maximum value of peak intensities of cathode luminescence of a wavelength corresponding to a band gap of gallium nitride and in a measured visual field of 0.1 mm×0.1 mm is 140 percent or higher of an average value of the peak intensities of the cathode luminescence, provided that the peak intensities of the cathode luminescence are measured on a surface of the gallium nitride substrate.
    Type: Application
    Filed: October 27, 2015
    Publication date: February 18, 2016
    Applicant: NGK INSULATORS, LTD.
    Inventors: Makoto Iwai, Masahiro Sakai, Katsuhiro Imai, Yoshitaka Kuraoka
  • Publication number: 20160049469
    Abstract: A supporting substrate for a composite substrate comprises a ceramic and has a polished surface for use in bonding. An orientation degree of the ceramic forming the supporting substrate .at the polished surface is 50% or higher, and an aspect ratio of each crystal grain included in the supporting substrate is 5.0 or less.
    Type: Application
    Filed: October 28, 2015
    Publication date: February 18, 2016
    Inventors: Jun YOSHIKAWA, Mikiya ICHIMURA, Katsuhiro IMAI