Patents by Inventor Yoshinao Kumagai

Yoshinao Kumagai 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: 7645340
    Abstract: A method for growing a crystal of an Al-containing III-V group compound semiconductor by the conventional HVPE method, characterized in that it comprises a step of reacting Al with hydrogen halide at a temperature of 700° C. or lower to form a halide of Al. The method has allowed the suppression of the formation of aluminum chloride (AlCl) or aluminum bromide (AlBr) reacting violently with quartz, which is the material of a reaction vessel for the growth, resulting in the achievement of the vapor phase growth of an Al-containing III-V group compound semiconductor at a rate of 100 microns/hr or more, which has lead to the mass-production of a substrate and a semiconductor element having satisfactory resistance to adverse environment.
    Type: Grant
    Filed: April 7, 2003
    Date of Patent: January 12, 2010
    Assignee: Tokyo University Agriculture and Technology TLO Co., Ltd.
    Inventors: Akinori Koukitu, Yoshinao Kumagai, Tomohiro Marui
  • Patent number: 7621999
    Abstract: An epitaxial growing method in which a crystal of AlxGa1-xN wherein x is a desirable constituent ratio can be grown on an Si substrate or sapphire substrate according to the HVPE process. Crystal of AlxGa1-xN is grown according to the HVPE process in which use is made of an aluminum material, a gallium material, an ammonia material and a carrier gas. The carrier gas consists of an inert gas and hydrogen, and the partial pressure of hydrogen is set so as to range from 0 to <0.1. As a result, the relationship between feeding ratio among materials and constituent ratio of grown crystal can be made linear, thereby enhancing the controllability of crystal composition.
    Type: Grant
    Filed: August 26, 2005
    Date of Patent: November 24, 2009
    Assignee: Tokyo University of Agriculture and Technology TLO Co., Ltd
    Inventors: Akinori Koukitu, Yoshinao Kumagai
  • Patent number: 7518216
    Abstract: A method of forming an iron-doped gallium nitride for a semi-insulating GaN substrate is provided. A substrate 1, such as a sapphire substrate having the (0001) plane, is placed on a susceptor of a metalorganic hydrogen chloride vapor phase apparatus 11. Next, gaseous iron compound GFe from a source 13 for an iron compound, such as ferrocene, and hydrogen chloride gas G1HCl from a hydrogen chloride source 15 are caused to react with each other in a mixing container 16 to generate gas GFeComp of an iron-containing reaction product, such as iron chloride (FeCl2). In association with the generation, the iron-containing reaction product GFeComp, first substance gas GN containing elemental nitrogen from a nitrogen source 17, and second substance gas GGa containing elemental gallium are supplied to a reaction tube 21 to form iron-doped gallium nitride 23 on the substrate 1.
    Type: Grant
    Filed: March 20, 2006
    Date of Patent: April 14, 2009
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Akinori Koukitu, Yoshinao Kumagai, Yoshiki Miura, Kikurou Takemoto, Fumitaka Sato
  • Publication number: 20090079036
    Abstract: A method of forming an iron-doped gallium nitride for a semi-insulating GaN substrate is provided. A substrate (1), such as a (0001)-cut sapphire substrate, is placed on a susceptor of a metalorganic hydrogen chloride vapor phase apparatus (11). Next, gaseous iron compound GFe from a source (13) for an iron compound, such as ferrocene, and hydrogen chloride gas G1HCl from a hydrogen chloride source (15) are caused to react with each other in a mixing container (16) to generate gas GFeComp of an iron-containing reaction product, such as iron chloride (FeCl2). In association with the generation, the iron-containing reaction product GFeComp, first substance gas GN containing elemental nitrogen from a nitrogen source (17), and second substance gas GGa containing elemental gallium are supplied to a reaction tube (21) to form iron-doped gallium nitride (23) on the substrate (1).
    Type: Application
    Filed: December 2, 2008
    Publication date: March 26, 2009
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Akinori Koukitu, Yoshinao Kumagai, Yoshiki Miura, Kikurou Takemoto, Fumitaka Sato
  • Publication number: 20080308814
    Abstract: There is disclosed a method for forming a gallium nitride layer of which resistivity is 1×106?·cm or more, including steps of: forming a gallium nitride layer containing iron on a substrate; and heating said gallium nitride layer formed on said substrate.
    Type: Application
    Filed: June 10, 2008
    Publication date: December 18, 2008
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Seiji NAKAHATA, Fumitaka Sato, Yoshiki Miura, Akinori Koukitu, Yoshinao Kumagai
  • Publication number: 20080063584
    Abstract: An epitaxial growing method in which a crystal of AlxGa1-xN wherein x is a desirable constituent ratio can be grown on an Si substrate or sapphire substrate according to the HVPE process. Crystal of AlxGa1-xN is grown according to the HVPE process in which use is made of an aluminum material, a gallium material, an ammonia material and a carrier gas. The carrier gas consists of an inert gas and hydrogen, and the partial pressure of hydrogen is set so as to range from 0 to <0.1. As a result, the relationship between feeding ratio among materials and constituent ratio of grown crystal can be made linear, thereby enhancing the controllability of crystal composition.
    Type: Application
    Filed: August 26, 2005
    Publication date: March 13, 2008
    Inventors: Akinori Koukitu, Yoshinao Kumagai
  • Publication number: 20070215982
    Abstract: A method of forming an iron-doped gallium nitride for a semi-insulating GaN substrate is provided. A substrate 1, such as a sapphire substrate having the (0001) plane, is placed on a susceptor of a metalorganic hydrogen chloride vapor phase apparatus 11. Next, gaseous iron compound GFe from a source 13 for an iron compound, such as ferrocene, and hydrogen chloride gas G1HCl from a hydrogen chloride source 15 are caused to react with each other in a mixing container 16 to generate gas GFeComp of an iron-containing reaction product, such as iron chloride (FeCl2). In association with the generation, the iron-containing reaction product GFeComp, first substance gas GN containing elemental nitrogen from a nitrogen source 17, and second substance gas GGa containing elemental gallium are supplied to a reaction tube 21 to form iron-doped gallium nitride 23 on the substrate 1.
    Type: Application
    Filed: March 20, 2006
    Publication date: September 20, 2007
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Akinori Koukitu, Yoshinao Kumagai, Yoshiki Miura, Kikurou Takemoto, Fumitaka Sato
  • Publication number: 20050166835
    Abstract: A method for growing a crystal of an Al-containing III-V group compound semiconductor by the conventional HVPE method, characterized in that it comprises a step of reacting Al with hydrogen halide at a temperature of 700° C. or lower to form a halide of Al. The method has allowed the suppression of the formation of aluminum chloride (AlCl) or aluminum bromide (AlBr) reacting violently with quartz, which is the material of a reaction vessel for the growth, resulting in the achievement of the vapor phase growth of an Al-containing III-V group compound semiconductor at a rate of 100 microns/hr or more, which has lead to the mass-production of a substrate and a semiconductor element having satisfactory resistance to adverse environment.
    Type: Application
    Filed: April 7, 2003
    Publication date: August 4, 2005
    Applicant: TOKYO UNIVERSITY AGRICULTURE AND TECHNOLOGY TLO CO
    Inventors: Akinori Koukitsu, Yoshinao Kumagai, Tomohiro Marui