Patents by Inventor Masaru Takizawa
Masaru Takizawa 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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Publication number: 20220149158Abstract: A Schottky barrier diode, including a first n-type semiconductor layer including a ?-Ga2O3-based single crystal epitaxial layer and having a first carrier concentration that determines reverse breakdown voltage and forward voltage, a second n-type semiconductor layer including a ?-Ga2O3-based single crystal substrate and having a second carrier concentration that is higher than the first carrier concentration and determines forward voltage, a Schottky electrode provided on a surface of the first n-type semiconductor layer on the opposite side to the second n-type semiconductor layer, and an ohmic electrode provided on a surface of the second n-type semiconductor layer on the opposite side to the first n-type semiconductor layer. The ?-Ga2O3-based single crystal substrate includes a surface that has a plane orientation rotated by an angle of not more than 37.5° from a (010) plane.Type: ApplicationFiled: January 24, 2022Publication date: May 12, 2022Inventors: Masaru TAKIZAWA, Akito KURAMATA
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Patent number: 11264466Abstract: A semiconductor device includes a semiconductor layer including a Ga2O3-based single crystal, and an electrode that is in contact with a surface of the semiconductor layer. The semiconductor layer is in Schottky-contact with the electrode and has an electron carrier concentration based on reverse withstand voltage and electric field-breakdown strength of the Ga2O3-based single crystal.Type: GrantFiled: February 26, 2020Date of Patent: March 1, 2022Assignee: TAMURA CORPORATIONInventors: Masaru Takizawa, Akito Kuramata
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Patent number: 11146040Abstract: Included is a semiconductor multilayer film in which a non-doped InAlN layer and a GaN layer formed on said InAlN layer and containing a dopant are stacked a plurality of times.Type: GrantFiled: March 13, 2018Date of Patent: October 12, 2021Assignees: MEIJO UNIVERSITY, STANLEY ELECTRIC CO., LTD.Inventors: Tetsuya Takeuchi, Isamu Akasaki, Kazuki Kiyohara, Masaru Takizawa, Ji-Hao Liang
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Publication number: 20210111538Abstract: Included is a semiconductor multilayer film in which a non-doped InAlN layer and a GaN layer formed on said InAlN layer and containing a dopant are stacked a plurality of times.Type: ApplicationFiled: March 13, 2018Publication date: April 15, 2021Applicants: MEIJO UNIVERSITY, STANLEY ELECTRIC CO., LTD.Inventors: Tetsuya TAKEUCHI, Isamu AKASAKI, Kazuki KIYOHARA, Masaru TAKIZAWA, Ji-Hao LIANG
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Publication number: 20200194560Abstract: A semiconductor device includes a semiconductor layer including a Ga2O3-based single crystal, and an electrode that is in contact with a surface of the semiconductor layer. The semiconductor layer is in Schottky-contact with the electrode and has an electron carrier concentration based on reverse withstand voltage and electric field-breakdown strength of the Ga2O3-based single crystal.Type: ApplicationFiled: February 26, 2020Publication date: June 18, 2020Inventors: Masaru TAKIZAWA, Akito KURAMATA
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Patent number: 10600874Abstract: A semiconductor device includes a semiconductor layer including a Ga2O3-based single crystal, and an electrode that is in contact with a surface of the semiconductor layer. The semiconductor layer is in Schottky-contact with the electrode and has an electron carrier concentration based on reverse withstand voltage and electric field-breakdown strength of the Ga2O3-based single crystal.Type: GrantFiled: February 17, 2017Date of Patent: March 24, 2020Assignee: TAMURA CORPORATIONInventors: Masaru Takizawa, Akito Kuramata
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Patent number: 10196756Abstract: A ?-Ga2O3-based single-crystal substrate includes a ?-Ga2O3-based single crystal, and a principal surface being a plane parallel to a b-axis of the ?-Ga2O3-based single crystal. A maximum value of ?? on an arbitrary straight line on the principal surface that passes through a center of the principal surface is not more than 0.7264. The ?? is a difference between a maximum value and a minimum value of values obtained by subtracting ?a from ?s at each of measurement positions, where ?s represents an angle defined by an X-ray incident direction and the principal surface at a peak position of an X-ray rocking curve on the straight line and ?a represents an angle on an approximated straight line obtained by using least-squares method to linearly approximate a curve representing a relationship between the ?s and the measurement positions thereof.Type: GrantFiled: June 29, 2015Date of Patent: February 5, 2019Assignees: TAMURA CORPORATION, KOHA CO., LTD.Inventors: Shinya Watanabe, Kimiyoshi Koshi, Yu Yamaoka, Kazuyuki Iizuka, Masaru Takizawa, Takekazu Masui
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Patent number: 9972972Abstract: A vertical cavity light emitting device includes: a first multilayer film reflector; a semiconductor structure layer that is formed on the first multilayer film reflector and includes a semiconductor layer of a first conductivity type, an active layer, and a semiconductor layer of a second conductivity type opposite to the first conductivity type; an insulating current confinement layer formed on the semiconductor layer of the second conductivity type; a through opening formed in the current confinement layer; a transparent electrode for covering the through opening and the current confinement layer, the transparent electrode being in contact with the semiconductor layer of the second conductivity type through the through opening; a second multilayer film reflector formed on the transparent electrode; and a mixed composition layer formed to be in contact with an edge of the through opening and in which the current confinement layer and the transparent electrode are mixed.Type: GrantFiled: November 9, 2016Date of Patent: May 15, 2018Assignee: STANLEY ELECTRIC CO., LTD.Inventors: Komei Tazawa, Ji-Hao Liang, Seiichiro Kobayashi, Masaru Takizawa, Keisuke Nakata
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Patent number: 9915010Abstract: Provided is one embodiment which is a method for growing a ?-Ga2O3-based single crystal which uses the EFG method and includes raising a Ga2O3 melt inside a crucible up to a die opening via a die slit such that a seed crystal is contacted with the Ga2O3-based melt in the opening of the die with a horizontal position of the seed crystal shifted in a width direction (W) from a center in the width direction (W) of the die, and pulling up the seed crystal contacting the Ga2O3-based melt so as to grown a ?-Ga2O3 single crystal.Type: GrantFiled: May 2, 2014Date of Patent: March 13, 2018Assignees: TAMURA CORPORATION, KOHA CO., LTD.Inventors: Kimiyoshi Koshi, Takekazu Masui, Masaru Takizawa
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Publication number: 20170162655Abstract: A semiconductor device includes a semiconductor layer including a Ga2O3-based single crystal, and an electrode that is in contact with a surface of the semiconductor layer. The semiconductor layer is in Schottky-contact with the electrode and has an electron carrier concentration based on reverse withstand voltage and electric field-breakdown strength of the Ga2O3-based single crystal.Type: ApplicationFiled: February 17, 2017Publication date: June 8, 2017Inventors: Masaru TAKIZAWA, Akito KURAMATA
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Publication number: 20170152610Abstract: A ?-Ga2O3-based single-crystal substrate includes a ?-Ga2O3-based single crystal, and a principal surface being a plane parallel to a b-axis of the ?-Ga2O3-based single crystal. A maximum value of ?? on an arbitrary straight line on the principal surface that passes through a center of the principal surface is not more than 0.7264. The ?? is a difference between a maximum value and a minimum value of values obtained by subtracting ?a from ?s at each of measurement positions, where ?s represents an angle defined by an X-ray incident direction and the principal surface at a peak position of an X-ray rocking curve on the straight line and ?a represents an angle on an approximated straight line obtained by using least-squares method to linearly approximate a curve representing a relationship between the ?s and the measurement positions thereof.Type: ApplicationFiled: June 29, 2015Publication date: June 1, 2017Applicants: TAMURA CORPORATION, KOHA CO., LTD.Inventors: Shinya WATANABE, Kimiyoshi KOSHI, Yu YAMAOKA, Kazuyuki IIZUKA, Masaru TAKIZAWA, Takekazu MASUI
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Publication number: 20170149213Abstract: A vertical cavity light emitting device includes: a first multilayer film reflector; a semiconductor structure layer that is formed on the first multilayer film reflector and includes a semiconductor layer of a first conductivity type, an active layer, and a semiconductor layer of a second conductivity type opposite to the first conductivity type; an insulating current confinement layer formed on the semiconductor layer of the second conductivity type; a through opening formed in the current confinement layer; a transparent electrode for covering the through opening and the current confinement layer, the transparent electrode being in contact with the semiconductor layer of the second conductivity type through the through opening; a second multilayer film reflector formed on the transparent electrode; and a mixed composition layer formed to be in contact with an edge of the through opening and in which the current confinement layer and the transparent electrode are mixed.Type: ApplicationFiled: November 9, 2016Publication date: May 25, 2017Applicant: STANLEY ELECTRIC CO., LTD.Inventors: Komei TAZAWA, Ji-Hao LIANG, Seiichiro KOBAYASHI, Masaru TAKIZAWA, Keisuke NAKATA
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Patent number: 9595586Abstract: A semiconductor device, includes an n-type semiconductor layer provided with a first semiconductor layer with a low electron carrier concentration and a second semiconductor layer with a high electron carrier concentration, an electrode that is in Schottky-contact with a surface of the first semiconductor layer, and an ohmic electrode formed on a surface of the second semiconductor layer. The n-type semiconductor layer is formed of a Ga2O3-based single crystal. The first semiconductor layer has an electron carrier concentration Nd based on reverse withstand voltage VRM and electric field-breakdown strength Em of the Ga2O3-based single crystal.Type: GrantFiled: July 12, 2016Date of Patent: March 14, 2017Assignee: TAMURA CORPORATIONInventors: Masaru Takizawa, Akito Kuramata
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Publication number: 20160322467Abstract: A semiconductor device, includes an n-type semiconductor layer provided with a first semiconductor layer with a low electron carrier concentration and a second semiconductor layer with a high electron carrier concentration, an electrode that is in Schottky-contact with a surface of the first semiconductor layer, and an ohmic electrode formed on a surface of the second semiconductor layer. The n-type semiconductor layer is formed of a Ga2O3-based single crystal. The first semiconductor layer has an electron carrier concentration Nd based on reverse withstand voltage VRM and electric field-breakdown strength Em of the Ga2O3-based single crystal.Type: ApplicationFiled: July 12, 2016Publication date: November 3, 2016Inventors: Masaru TAKIZAWA, Akito KURAMATA
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Patent number: 9431489Abstract: A ?-Ga2O3-based single crystal substrate includes an average dislocation density of less than 7.31×104 cm?2. The average dislocation density may be not more than 6.14×104 cm?2. The substrate may further include a main surface including a plane orientation of (?201), (101) or (001). The substrate may be free from any twinned crystal.Type: GrantFiled: February 27, 2015Date of Patent: August 30, 2016Assignees: TAMURA CORPORATION, KOHA CO., LTD.Inventors: Kimiyoshi Koshi, Shinya Watanabe, Masaru Takizawa, Yu Yamaoka, Makoto Watanabe, Takekazu Masui
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Patent number: 9412882Abstract: A Schottky barrier diode includes an n-type semiconductor layer including a Ga2O3-based compound semiconductor with n-type conductivity, and an electrode layer that is in Schottky-contact with the n-type semiconductor layer. A first semiconductor layer in Schottky-contact with the electrode layer and a second semiconductor layer having an electron carrier concentration higher than the first semiconductor layer are formed in the n-type semiconductor layer. The second semiconductor layer includes a ?-Ga2O3 substrate including a main plane rotated by an angle not less than 50° and not more than 90° with respect to a (100) plane thereof.Type: GrantFiled: October 20, 2015Date of Patent: August 9, 2016Assignee: TAMURA CORPORATIONInventors: Masaru Takizawa, Akito Kuramata
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Patent number: 9349915Abstract: A ?-Ga2O3-based single crystal substrate includes a ?-Ga2O3-based single crystal. The ?-Ga2O3-based single crystal includes a full width at half maximum of an x-ray rocking curve of less than 75 seconds.Type: GrantFiled: February 26, 2015Date of Patent: May 24, 2016Assignees: TAMURA CORPORATION, KOHA CO., LTD.Inventors: Kimiyoshi Koshi, Shinya Watanabe, Masaru Takizawa, Yu Yamaoka, Daiki Wakimoto, Makoto Watanabe
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Publication number: 20160115621Abstract: Provided is one embodiment which is a method for growing a ?-Ga2O3-based single crystal which uses the EFG method and includes raising a Ga2O3 melt inside a crucible up to a die opening via a die slit such that a seed crystal is contacted with the Ga2O3-based melt in the opening of the die with a horizontal position of the seed crystal shifted in a width direction (W) from a center in the width direction (W) of the die, and pulling up the seed crystal contacting the Ga2O3-based melt so as to grown a ?-Ga2O3 single crystal.Type: ApplicationFiled: May 2, 2014Publication date: April 28, 2016Applicants: TAMURA CORPORATION, KOHA CO., LTD.Inventors: Kimiyoshi KOSHI, Takekazu MASUI, Masaru TAKIZAWA
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Publication number: 20160043238Abstract: A Schottky barrier diode includes an n-type semiconductor layer including a Ga2O3-based compound semiconductor with n-type conductivity, and an electrode layer that is in Schottky-contact with the n-type semiconductor layer. A first semiconductor layer in Schottky-contact with the electrode layer and a second semiconductor layer having an electron carrier concentration higher than the first semiconductor layer are formed in the n-type semiconductor layer. The second semiconductor layer includes a ?-Ga2O3 substrate including a main plane rotated by an angle not less than 50° and not more than 90° with respect to a (100) plane thereof.Type: ApplicationFiled: October 20, 2015Publication date: February 11, 2016Inventors: MASARU TAKIZAWA, Akito KURAMATA
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Publication number: 20150380501Abstract: A ?-Ga2O3-based single crystal substrate includes an average dislocation density of less than 7.31×104 cm?2. The average dislocation density may be not more than 6.14×104 cm?2. The substrate may further include a main surface including a plane orientation of (?201), (101) or (001). The substrate may be free from any twinned crystal.Type: ApplicationFiled: February 27, 2015Publication date: December 31, 2015Inventors: Kimiyoshi KOSHI, Shinya Watanabe, Masaru Takizawa, Yu Yamaoka, Makoto Watanabe, Takekazu Masui