Patents by Inventor Kazumasa Kiyomi

Kazumasa Kiyomi 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: 9112096
    Abstract: The method for producing a group III nitride semiconductor crystal comprises preparing a seed crystal having a non-polar plane followed by growing a group III nitride semiconductor from the non-polar plane in a vapor phase, wherein the growing includes growing the group III nitride semiconductor so as to extend in the +C-axis direction of the seed crystal. A group III-V nitride semiconductor crystal having high quality and a large-area non-polar plane can be obtained by the method.
    Type: Grant
    Filed: July 1, 2013
    Date of Patent: August 18, 2015
    Assignee: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Kenji Fujito, Kazumasa Kiyomi
  • Publication number: 20130320394
    Abstract: The method for producing a group III nitride semiconductor crystal comprises preparing a seed crystal having a non-polar plane followed by growing a group III nitride semiconductor from the non-polar plane in a vapor phase, wherein the growing includes growing the group III nitride semiconductor so as to extend in the +C-axis direction of the seed crystal. A group III-V nitride semiconductor crystal having high quality and a large-area non-polar plane can be obtained by the method.
    Type: Application
    Filed: July 1, 2013
    Publication date: December 5, 2013
    Applicant: Mitsubishi Chemical Corporation
    Inventors: Kenji Fujito, Kazumasa Kiyomi
  • Publication number: 20120305983
    Abstract: The method for producing a group III nitride semiconductor crystal comprises preparing a seed crystal having a non-polar plane followed by growing a group III nitride semiconductor from the non-polar plane in a vapor phase, wherein the growing includes growing the group III nitride semiconductor so as to extend in the +C-axis direction of the seed crystal. A group III-V nitride semiconductor crystal having high quality and a large-area non-polar plane can be obtained by the method.
    Type: Application
    Filed: August 10, 2012
    Publication date: December 6, 2012
    Applicant: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Kenji Fujito, Kazumasa Kiyomi
  • Patent number: 8269251
    Abstract: The method for producing a group III nitride semiconductor crystal of the invention comprises a step of preparing a seed crystal having a non-polar plane followed by growing a group III nitride semiconductor from the non-polar plane in a vapor phase, wherein the growing step includes growing the group III nitride semiconductor so as to extend in the +C-axis direction of the seed crystal. A group III-V nitride semiconductor crystal having high quality and a large-area non-polar plane can be obtained by the method.
    Type: Grant
    Filed: May 16, 2008
    Date of Patent: September 18, 2012
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Kenji Fujito, Kazumasa Kiyomi
  • Publication number: 20120112320
    Abstract: A production process for a nitride semiconductor crystal, comprising growing a semiconductor layer on a seed substrate to obtain a nitride semiconductor crystal, wherein the seed substrate comprises a plurality of seed substrates made of the same material, at least one of the plurality of seed substrates differs in the off-angle from the other seed substrates, and a single semiconductor layer is grown by disposing the plurality of seed substrates in a semiconductor crystal production apparatus, such that when the single semiconductor layer is grown on the plurality of seed substrates, the off-angle distribution in the single semiconductor layer becomes smaller than the off-angle distribution in the plurality of seed substrates.
    Type: Application
    Filed: December 1, 2011
    Publication date: May 10, 2012
    Applicant: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Shuichi KUBO, Kenji Shimoyama, Kazumasa Kiyomi, Kenji Fujito, Yutaka Mikawa
  • Patent number: 8142566
    Abstract: A Ga-containing nitride semiconductor single crystal characterized in that (a) the maximum reflectance measured by irradiating the Ga-containing nitride semiconductor single crystal with light at a wavelength of 450 nm is 20% or less and the difference between the maximum reflectance and the minimum reflectance is within 10%, (b) the ratio of maximum value to minimum value (maximum value/minimum value) of the dislocation density measured by a cathode luminescence method is 10 or less, and/or (c) the lifetime measured by a time-resolved photoluminescence method is 95 ps or more.
    Type: Grant
    Filed: August 5, 2005
    Date of Patent: March 27, 2012
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Kazumasa Kiyomi, Hirobumi Nagaoka, Hirotaka Oota, Isao Fujimura
  • Patent number: 7794541
    Abstract: Disclosed is a method of manufacturing a GaN-based material having high thermal conductivity. A gallium nitride-based material is grown by HVPE (Hydride Vapor Phase Epitaxial Growth) by supplying a carrier gas (G1) containing H2 gas, GaCl gas (G2), and NH3 gas (G3) to a reaction chamber (10), and setting the growth temperature at 900 (° C.) (inclusive) to 1,200 (° C.) (inclusive), the growth pressure at 8.08×104 (Pa) (inclusive) to 1.21×105 (Pa) (inclusive), the partial pressure of the GaCl gas (G2) at 1.0×104 (Pa) (inclusive) to 1.0×104 (Pa) (inclusive), and the partial pressure of the NH3 gas (G3) at 9.1×102 (Pa) (inclusive) to 2.0×104 (Pa) (inclusive).
    Type: Grant
    Filed: March 8, 2007
    Date of Patent: September 14, 2010
    Assignees: Tohoku University, Mitsubishi Chemical Corporation
    Inventors: Hiroyuki Shibata, Yoshio Waseda, Kenji Shimoyama, Kazumasa Kiyomi, Hirobumi Nagaoka
  • Publication number: 20100162945
    Abstract: A method to make gallium nitride-based material by Hydride Vapor Phase Epitaxial Growth is provided.
    Type: Application
    Filed: March 8, 2010
    Publication date: July 1, 2010
    Applicants: Tohoku University, Mitsubishi Chemical Corporation
    Inventors: Hiroyuki Shibata, Yoshio Waseda, Kenji Shimoyama, Kazumasa Kiyomi, Hirobumi Nagaoka
  • Publication number: 20100148212
    Abstract: The method for producing a group III nitride semiconductor crystal of the invention comprises a step of preparing a seed crystal having a non-polar plane followed by growing a group III nitride semiconductor from the non-polar plane in a vapor phase, wherein the growing step includes growing the group III nitride semiconductor so as to extend in the +C-axis direction of the seed crystal. A group III-V nitride semiconductor crystal having high quality and a large-area non-polar plane can be obtained by the method.
    Type: Application
    Filed: May 16, 2008
    Publication date: June 17, 2010
    Applicant: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Kenji Fujito, Kazumasa Kiyomi
  • Publication number: 20100140536
    Abstract: A gallium nitride-based material prepared by a vertical Hydride Vapor Phase Epitaxial Growth method which has thermal conductivity of at least 2.8×102 W/m·K at 25° C. is provided.
    Type: Application
    Filed: February 17, 2010
    Publication date: June 10, 2010
    Applicants: Tohoku University, Mitsubishi Chemical Corporation
    Inventors: Hiroyuki SHIBATA, Yoshio Waseda, Kenji Shimoyama, Kazumasa Kiyomi, Hirobumi Nagaoka
  • Publication number: 20090081110
    Abstract: Disclosed is a method of manufacturing a GaN-based material having high thermal conductivity. A gallium nitride-based material is grown by HVPE (Hydride Vapor Phase Epitaxial Growth) by supplying a carrier gas (G1) containing H2 gas, GaCl gas (G2), and NH3 gas (G3) to a reaction chamber (10), and setting the growth temperature at 900 (° C.) (inclusive) to 1,200 (° C.) (inclusive), the growth pressure at 8.08×104 (Pa) (inclusive) to 1.21×105 (Pa) (inclusive), the partial pressure of the GaCl gas (G2) at 1.0×104 (Pa) (inclusive) to 1.0×104 (Pa) (inclusive), and the partial pressure of the NH3 gas (G3) at 9.1×102 (Pa) (inclusive) to 2.0×104 (Pa) (inclusive).
    Type: Application
    Filed: March 8, 2007
    Publication date: March 26, 2009
    Applicants: Tohoku University, MITSUBISHI CHEMICAL CORPORATION
    Inventors: Hiroyuki Shibata, Yoshio Waseda, Kenji Shimoyama, Kazumasa Kiyomi, Hirobumi Nagaoka
  • Publication number: 20090026488
    Abstract: A nitride semiconductor material comprising a semiconductor or dielectric substrate having thereon a first nitride semiconductor layer group, wherein the surface of the first nitride semiconductor layer group has an RMS of 5 nm or less, a variation of X-ray half-width within ±30%, a light reflectance of the surface of 15% or more, and a variation thereof of ±10% or less, and the thickness of said first nitride semiconductor layer group is 25 ?m or more. This nitride semiconductor material is excellent in uniformity and stability, assured of a low production cost, and useful as a substrate for a nitride semiconductor-type device.
    Type: Application
    Filed: February 8, 2006
    Publication date: January 29, 2009
    Applicant: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Kazumasa Kiyomi, Hideyoshi Horie, Toshio Ishiwatari, Isao Fujimura
  • Publication number: 20080308812
    Abstract: A Ga-containing nitride semiconductor single crystal characterized in that (a) the maximum reflectance measured by irradiating the Ga-containing nitride semiconductor single crystal with light at a wavelength of 450 nm is 20% or less and the difference between the maximum reflectance and the minimum reflectance is within 10%, (b) the ratio of maximum value to minimum value (maximum value/minimum value) of the dislocation density measured by a cathode luminescence method is 10 or less, and/or (c) the lifetime measured by a time-resolved photoluminescence method is 95 ps or more.
    Type: Application
    Filed: August 5, 2005
    Publication date: December 18, 2008
    Applicant: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Kazumasa Kiyomi, Hirobumi Nagaoka, Hirotaka Oota, Isao Fujimura
  • Patent number: 6807213
    Abstract: This application discloses a semiconductor optical device apparatus having on a substrate, at least, a compound semiconductor layer containing an active layer, a protection film having a stripe-shaped opening formed on the compound semiconductor layer, and a ridge type compound semiconductor layer formed as to cover the stripe-shaped opening having a smaller refractive index than the refractive index of the active layer, has a feature that a width (WC) at an opening center of the stripe-shaped opening is different from either or both of a width (WF) of the opening front end and a width (WR) of the opening rear end. According to the invention, a semiconductor optical device apparatus capable of operating with a high output, and a semiconductor optical device apparatus having a small beam spot diameter, and the like can be manufactured where the width of the stripe-shaped opening is properly controlled.
    Type: Grant
    Filed: February 23, 2000
    Date of Patent: October 19, 2004
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Kenji Shimoyama, Nobuyuki Hosoi, Kazumasa Kiyomi, Yoshihito Sato, Satosi Kikuchi
  • Patent number: 6744066
    Abstract: The semiconductor device according to the present invention comprises a V-groove having V-shaped cross-section formed on a semiconductor substrate or on an epitaxial growth layer grown on a semiconductor substrate, and an active layer is provided only at the bottom of said V-groove. The method for manufacturing a semiconductor device according to the present invention comprises the steps of forming a stripe-like etching protective film in <011> direction of a semiconductor substrate or an epitaxial growth layer grown on it, performing gas etching using hydrogen chloride as etching gas on a semiconductor substrate or on an epitaxial growth layer grown on a semiconductor substrate to form a V-groove, and forming an active layer at the bottom of said V-groove.
    Type: Grant
    Filed: February 20, 2001
    Date of Patent: June 1, 2004
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Kenji Shimoyama, Kazumasa Kiyomi, Hideki Gotoh, Satoru Nagao
  • Patent number: 6707071
    Abstract: In a semiconductor light-emitting device including a substrate, a first compound semiconductor layer including an active layer formed on the substrate, a second compound semiconductor layer of a ridge type formed on the first compound semiconductor layer, and a protective film formed above the first compound semiconductor layer on both sides of the second compound semiconductor layer, the disclosed semiconductor light-emitting device has a current blocking layer formed above the first compound semiconductor layer outside the protective film. This semiconductor light-emitting device is with a high production yield since readily cleaved and assembled, with adequately squeezed currents, and with, when assembled in the junction-down type, a high output and a longer life span.
    Type: Grant
    Filed: March 13, 2002
    Date of Patent: March 16, 2004
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Makiko Hashimoto, Nobuyuki Hosoi, Kenji Shimoyama, Katsushi Fujii, Yoshihito Sato, Kazumasa Kiyomi
  • Patent number: 6589807
    Abstract: The semiconductor device according to the present invention comprises a V-groove having V-shaped cross-section formed on a semiconductor substrate or on an epitaxial growth layer grown on a semiconductor substrate, and an active layer is provided only at the bottom of said V-groove. The method for manufacturing a semiconductor device according to the present invention comprises the steps of forming a stripe-like etching protective film in <011> direction of a semiconductor substrate or an epitaxial growth layer grown on it, performing gas etching using hydrogen chloride as etching gas on a semiconductor substrate or on an epitaxial growth layer grown on a semiconductor substrate to form a V-groove, and forming an active layer at the bottom of said V-groove.
    Type: Grant
    Filed: May 31, 2001
    Date of Patent: July 8, 2003
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Kenji Shimoyama, Kazumasa Kiyomi, Hideki Gotoh, Satoru Nagao
  • Publication number: 20020125488
    Abstract: In a semiconductor light-emitting device including a substrate, a first compound semiconductor layer including an active layer formed on the substrate, a second compound semiconductor layer of a ridge type formed on the first compound semiconductor layer, and a protective film formed above the first compound semiconductor layer on both sides of the second compound semiconductor layer, the disclosed semiconductor light-emitting device has a current blocking layer formed above the first compound semiconductor layer outside the protective film. This semiconductor light-emitting device is with a high production yield since readily cleaved and assembled, with adequately squeezed currents, and with, when assembled in the junction-down type, a high output and a longer life span.
    Type: Application
    Filed: March 13, 2002
    Publication date: September 12, 2002
    Applicant: Mitsubishi Chemical Corporation
    Inventors: Makiko Hashimoto, Nobuyuki Hosoi, Kenji Shimoyama, Katsushi Fujii, Yoshihito Sato, Kazumasa Kiyomi
  • Patent number: 6387721
    Abstract: In a semiconductor light-emitting device including a substrate, a first compound semiconductor layer including an active layer formed on the substrate, a second compound semiconductor layer of a ridge type formed on the first compound semiconductor layer, and a protective film formed above the first compound semiconductor layer on both sides of the second compound semiconductor layer, the disclosed semiconductor light-emitting device has a current blocking layer formed above the first compound semiconductor layer outside the protective film. This semiconductor light-emitting device is with a high production yield since readily cleaved and assembled, with adequately squeezed currents, and with, when assembled in the junction-down type, a high output and a longer life span.
    Type: Grant
    Filed: September 24, 1999
    Date of Patent: May 14, 2002
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Makiko Hashimoto, Nobuyuki Hosoi, Kenji Shimoyama, Katsushi Fujii, Yoshihito Sato, Kazumasa Kiyomi
  • Publication number: 20020014622
    Abstract: The semiconductor device according to the present invention comprises a V-groove having V-shaped cross-section formed on a semiconductor substrate or on an epitaxial growth layer grown on a semiconductor substrate, and an active layer is provided only at the bottom of said V-groove. The method for manufacturing a semiconductor device according to the present invention comprises the steps of forming a stripe-like etching protective film in <011> direction of a semiconductor substrate or an epitaxial growth layer grown on it, performing gas etching using hydrogen chloride as etching gas on a semiconductor substrate or on an epitaxial growth layer grown on a semiconductor substrate to form a V-groove, and forming an active layer at the bottom of said V-groove.
    Type: Application
    Filed: May 31, 2001
    Publication date: February 7, 2002
    Applicant: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Kenji Shimoyama, Kazumasa Kiyomi, Hideki Gotoh, Satoru Nagao