Patents by Inventor Toshiaki Asahi
Toshiaki Asahi 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).
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Patent number: 11935974Abstract: Provided is a semiconductor material having improved oxidation resistance. The semiconductor material has a single crystal represented by the following composition formula: Mg2Sn·Zna??Composition formula: in which, a is a Zn content of from 0.05 to 1 at % relative to Mg2Sn.Type: GrantFiled: May 23, 2019Date of Patent: March 19, 2024Assignees: IBARAKI UNIVERSITY, JX METALS CORPORATIONInventors: Haruhiko Udono, Toshiaki Asahi
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Publication number: 20220013675Abstract: Provided is a semiconductor material having improved oxidation resistance. The semiconductor material has a single crystal represented by the following composition formula: Mg2Sn.Zna??Composition formula: in which, a is a Zn content of from 0.05 to 1 at % relative to Mg2Sn.Type: ApplicationFiled: May 23, 2019Publication date: January 13, 2022Applicants: Ibaraki University, JX Nippon Mining & Metals CorporationInventors: Haruhiko UDONO, Toshiaki ASAHI
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Patent number: 11011664Abstract: Provided is a semiconductor photodiode which has an electrode structure having not only high adhesion to a Mg2Si material but also improved overall performance including photosensitivity. A photodiode comprising: a pn junction of a magnesium silicide crystal; an electrode comprising a material that is in contact with p-type magnesium silicide; and an electrode comprising a material that is in contact with n-type magnesium silicide, wherein the material that is in contact with p-type magnesium silicide is a material which has a work function of 4.81 eV or more and reacts with silicon to form a silicide or form an alloy with magnesium.Type: GrantFiled: September 20, 2018Date of Patent: May 18, 2021Assignees: IBARAKI UNIVERSITY, JX NIPPON MINING & METALS CORPORATIONInventors: Haruhiko Udono, Toshiaki Asahi
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Patent number: 10641807Abstract: In an optical modulator capable of modulating incident laser beam L by a compound semiconductor single crystal having a property of generating an electro-optic effect, the attenuation of the signal strength in a low frequency band is prevented without lowering the carrier concentration of the compound semiconductor. The optical modulator 23 comprises: incidence limiting means 25 which is provided on or near an incidence plane 24a, on which the laser beam L can be incident, of the compound semiconductor single crystal 24 so as to limit incidence of light other than the laser beam L on the incidence plane 24a; and a shielding member 26 which is formed from a low-permittivity material having a light blocking effect, and covers a surface 24c of the compound semiconductor single crystal 24 extending along a traveling direction of the laser beam L that entered the compound semiconductor single crystal 24.Type: GrantFiled: October 7, 2016Date of Patent: May 5, 2020Assignees: JX NIPPON MINING & METALS CORPORATIONInventors: Mitsuru Shinagawa, Toshiaki Asahi
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Publication number: 20200052142Abstract: Provided is a semiconductor photodiode which has an electrode structure having not only high adhesion to a Mg2Si material but also improved overall performance including photosensitivity. A photodiode comprising: a pn junction of a magnesium silicide crystal; an electrode comprising a material that is in contact with p-type magnesium silicide; and an electrode comprising a material that is in contact with n-type magnesium silicide, wherein the material that is in contact with p-type magnesium silicide is a material which has a work function of 4.81 eV or more and reacts with silicon to form a silicide or form an alloy with magnesium.Type: ApplicationFiled: September 20, 2018Publication date: February 13, 2020Applicants: IBARAKI UNIVERSITY, JX NIPPON MINING & METALS CORPORATIONInventors: Haruhiko UDONO, Toshiaki ASAHI
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Publication number: 20180238949Abstract: In an optical modulator capable of modulating incident laser beam L by a compound semiconductor single crystal having a property of generating an electro-optic effect, the attenuation of the signal strength in a low frequency band is prevented without lowering the carrier concentration of the compound semiconductor. The optical modulator 23 comprises: incidence limiting means 25 which is provided on or near an incidence plane 24a, on which the laser beam L can be incident, of the compound semiconductor single crystal 24 so as to limit incidence of light other than the laser beam L on the incidence plane 24a; and a shielding member 26 which is formed from a low-permittivity material having a light blocking effect, and covers a surface 24c of the compound semiconductor single crystal 24 extending along a traveling direction of the laser beam L that entered the compound semiconductor single crystal 24.Type: ApplicationFiled: October 7, 2016Publication date: August 23, 2018Inventors: Mitsuru Shinagawa, Toshiaki Asahi
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Patent number: 8476171Abstract: The present invention is to provide a heat treatment method for effectively eliminating Te deposits in a ZnTe single crystal substrate, and a ZnTe single crystal substrate having an optical characteristic suitable for use of a light modulation element and having a thickness of 1 mm or more. A heat treatment method of a ZnTe single crystal substrate, includes: a first step of increasing a temperature the ZnTe single crystal substrate to a first heat treatment temperature T1, and retaining the temperature of the substrate for a predetermined time; and a second step of gradually reducing the temperature of the substrate from the first heat treatment temperature T1 to a second heat treatment temperature T2 lower than the heat treatment temperature T1 with a predetermined rate, wherein the first heat treatment temperature T1 is set in a range of 700° C.?T1?1250° C. and the second heat treatment temperature T2 is set in a range of T2?T1?50.Type: GrantFiled: July 18, 2006Date of Patent: July 2, 2013Assignee: Nippon Mining & Metals Co., Ltd.Inventors: Toshiaki Asahi, Kenji Sato, Takayuki Shimizu
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Publication number: 20130029278Abstract: Provided is a method for synthesizing group II-VI compound semiconductor polycrystals in which synthesis can be accomplished without the use of a quart ampoule as the polycrystal synthesis vessel, and as a result it is possible to use a larger vessel without reducing yield, and costs can thereby be reduced. Two or more starting elements are introduced to a semi-airtight pBN inner vessel (6a), the inner vessel is introduced to a semi-airtight heat-resistant outer vessel (6b) and placed in a high-pressure furnace (1) having a heating means (7), the air inside the high-pressure furnace is evacuated and the furnace is filled with an inert gas under a predetermined pressure, the outer vessel and inner vessel are heated and the temperature is raised using the heating means, the starting elements inside the inner vessel are melted and reacted, and the temperature is then gradually lowered to promote growth of polycrystals.Type: ApplicationFiled: March 11, 2011Publication date: January 31, 2013Applicant: JX NIPPON MINING & METALS CORPORATIONInventors: Toshiaki Asahi, Akira Noda
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Publication number: 20110236297Abstract: The present invention is to provide a heat treatment method for effectively eliminating Te deposits in a ZnTe single crystal substrate, and a ZnTe single crystal substrate having an optical characteristic suitable for use of a light modulation element and having a thickness of 1 mm or more. A heat treatment method of a ZnTe single crystal substrate, includes: a first step of increasing a temperature the ZnTe single crystal substrate to a first heat treatment temperature T1, and retaining the temperature of the substrate for a predetermined time; and a second step of gradually reducing the temperature of the substrate from the first heat treatment temperature T1 to a second heat treatment temperature T2 lower than the heat treatment temperature T1 with a predetermined rate, wherein the first heat treatment temperature T1 is set in a range of 700° C.?T1?1250° C. and the second heat treatment temperature T2 is set in a range of T2?T1?50.Type: ApplicationFiled: June 13, 2011Publication date: September 29, 2011Inventors: Toshiaki Asahi, Kenji Sato, Takayuki Shimizu
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Patent number: 7696073Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: GrantFiled: November 26, 2007Date of Patent: April 13, 2010Assignee: Nippon Mining & Metals Co., Ltd.Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi
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Patent number: 7629625Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: GrantFiled: November 26, 2007Date of Patent: December 8, 2009Assignee: Nippon Mining & Metals Co., Ltd.Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi
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Patent number: 7521282Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: GrantFiled: November 26, 2007Date of Patent: April 21, 2009Assignee: Nippon Mining & Metals Co., Ltd.Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi
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Patent number: 7517720Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: GrantFiled: November 26, 2007Date of Patent: April 14, 2009Assignee: Nippon Mining & Metals Co., Ltd.Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi
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Publication number: 20090042002Abstract: The present invention is to provide a heat treatment method for effectively eliminating Te deposits in a ZnTe single crystal substrate, and a ZnTe single crystal substrate having an optical characteristic suitable for use of a light modulation element and having a thickness of 1 mm or more. A heat treatment method of a ZnTe single crystal substrate, includes: a first step of increasing a temperature the ZnTe single crystal substrate to a first heat treatment temperature T1, and retaining the temperature of the substrate for a predetermined time; and a second step of gradually reducing the temperature of the substrate from the first heat treatment temperature T1 to a second heat treatment temperature T2 lower than the heat treatment temperature T1 with a predetermined rate, wherein the first heat treatment temperature T1 is set in a range of 700° C.?T1?1250° C. and the second heat treatment temperature T2 is set in a range of T2?T1?50.Type: ApplicationFiled: July 18, 2006Publication date: February 12, 2009Inventors: Toshiaki Asahi, Kenji Sato, Takayuki Shimizu
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Publication number: 20080090386Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: ApplicationFiled: November 26, 2007Publication date: April 17, 2008Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi
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Publication number: 20080090328Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: ApplicationFiled: November 26, 2007Publication date: April 17, 2008Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi
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Publication number: 20080089831Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: ApplicationFiled: November 26, 2007Publication date: April 17, 2008Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi
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Publication number: 20080090327Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: ApplicationFiled: November 26, 2007Publication date: April 17, 2008Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi
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Publication number: 20080090390Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: ApplicationFiled: November 26, 2007Publication date: April 17, 2008Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi
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Patent number: 7358159Abstract: The present invention relates to a method for producing an n-type ZnTe system compound semiconductor single crystal having high carrier concentration and low resistivity, the ZnTe system compound semiconductor single crystal, and a semiconductor device produced by using the ZnTe system compound semiconductor as a base member. Concretely, a first dopant and a second dopant are co-doped into the ZnTe system compound semiconductor single crystal so that the number of atoms of the second dopant becomes smaller than the number of atoms of the first dopant, the first dopant being for controlling a conductivity type of the ZnTe system compound semiconductor to a first conductivity type, and the second dopant being for controlling the conductivity type to a second conductivity type different from the first conductivity type. By the present invention, a desired carrier concentration can be achieved with a doping amount smaller than in earlier technology, and crystallinity of the obtained crystal can be improved.Type: GrantFiled: March 20, 2002Date of Patent: April 15, 2008Assignee: Nippon Mining & Metals Co., Ltd.Inventors: Tetsuya Yamamoto, Atsutoshi Arakawa, Kenji Sato, Toshiaki Asahi