Patents by Inventor Masayoshi Takemi
Masayoshi Takemi 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: 20110177678Abstract: A method for manufacturing a nitride semiconductor device includes forming an n-type nitride-based semiconductor layer on a substrate; forming an active layer of a nitride-based semiconductors including In on the n-type nitride-based semiconductor layer using ammonia and a hydrazine derivative as group-V element source materials and a carrier gas including hydrogen; and forming a p-type nitride-based semiconductor layer on the active layer using ammonia and a hydrazine derivative as group-V element source materials.Type: ApplicationFiled: September 24, 2010Publication date: July 21, 2011Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Akihito Ohno, Masayoshi Takemi, Takahiro Yamamoto
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Patent number: 7923742Abstract: A nitride semiconductor laminated structure comprises: a substrate; a first p-type nitride semiconductor layer formed using an organometallic compound as a Group III element source material, a p-type impurity source material, and ammonia as a Group V element source material, with the hydrogen concentration in the first p-type nitride semiconductor layer being 1×1019 cm?3 or less; and a second p-type nitride semiconductor layer on the first p-type nitride semiconductor layer formed using an organometallic compound as a Group III element source material, a p-type impurity source material, and ammonia and a hydrazine derivative as Group V element source materials, with the carbon concentration in the second p-type nitride semiconductor layer being 1×1018 cm?3 or less.Type: GrantFiled: March 16, 2009Date of Patent: April 12, 2011Assignee: Mitsubishi Electric CorporationInventors: Akihito Ohno, Masayoshi Takemi, Nobuyuki Tomita
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Publication number: 20100316080Abstract: A semiconductor optical element includes a p-type InP substrate doped with Zn; and a diffusion blocking layer doped with Ru, a p-type InP cladding layer, an active layer, and an n-type InP cladding layer sequentially arranged on the p-type InP substrate.Type: ApplicationFiled: February 5, 2010Publication date: December 16, 2010Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Harunaka Yamaguchi, Chikara Watatani, Masayoshi Takemi
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Publication number: 20100289056Abstract: A semiconductor laser device comprises an n-type cladding layer, a p-type cladding layer, and an active layer which is sandwiched between the n-type cladding layer and the p-type cladding layer. The p-type cladding layer contains magnesium as a dopant impurity. Further, an n-type diffusion blocking layer of a nitride compound semiconductor material located between the active layer and the p-type cladding layer and is InxAlyGa1-x-yN, where x?0, y?0, and (x+y)<1. The n-type diffusion blocking layer preferably has a concentration of a dopant impurity producing n-type conductivity in a range from 5×1017 cm?3 to 5×1019 cm?3.Type: ApplicationFiled: July 14, 2010Publication date: November 18, 2010Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Akihito Ohno, Masayoshi Takemi, Nobuyuki Tomita
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Patent number: 7825012Abstract: A method for manufacturing a nitride semiconductor device, includes forming a p-type nitride semiconductor layer on a substrate, from an organic metal compound as a group III element source material, ammonia and a hydrazine derivative as group V element source materials, and a Mg source material gas as a p-type impurity source material. The flow velocity of the source material gases including the group III element source material, the group V element source materials, and the p-type impurity source material is more than 0.2 m/sec.Type: GrantFiled: July 13, 2009Date of Patent: November 2, 2010Assignee: Mitsubishi Electric CorporationInventors: Akihito Ohno, Masayoshi Takemi
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Patent number: 7763486Abstract: A nitride semiconductor stacked structure having good working efficiency includes a p-type nitride semiconductor layer of low resistance, which is formed from an organometallic compound, compounds including Group V elements, including ammonia and a hydrazine derivative, and a p-type impurity material on a substrate. The p-type nitride layer has a carbon concentration not higher than 1×1018 cm?3.Type: GrantFiled: December 5, 2007Date of Patent: July 27, 2010Assignee: Mitsubishi Electric CorporationInventors: Akihito Ohno, Masayoshi Takemi, Nobuyuki Tomita
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Publication number: 20100075483Abstract: A method for manufacturing a nitride semiconductor device, includes forming a p-type nitride semiconductor layer on a substrate, from an organic metal compound as a group III element source material, ammonia and a hydrazine derivative as group V element source materials, and a Mg source material gas as a p-type impurity source material. The flow velocity of the source material gases including the group III element source material, the group V element source materials, and the p-type impurity source material is more than 0.2 m/sec.Type: ApplicationFiled: July 13, 2009Publication date: March 25, 2010Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Akihito Ohno, Masayoshi Takemi
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Patent number: 7632695Abstract: A technique is provided which enables formation of nitride semiconductor layers with excellent flatness and excellent crystallinity on a gallium nitride substrate (GaN substrate), while improving the producibility of the semiconductor device using the GaN substrate. A gallium nitride substrate is prepared which has an upper surface having an off-angle of not less than 0.1° nor more than 1.0° in a <1-100> direction, with respect to a (0001) plane. Then, a plurality of nitride semiconductor layers including an n-type semiconductor layer are stacked on the upper surface of the gallium nitride substrate to form a semiconductor device such as a semiconductor laser.Type: GrantFiled: November 16, 2007Date of Patent: December 15, 2009Assignee: Mitsubishi Denki Kabushiki KaishaInventors: Akihito Ohno, Masayoshi Takemi, Nobuyuki Tomita
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Publication number: 20090236589Abstract: A nitride semiconductor laminated structure comprises: a substrate; a first p-type nitride semiconductor layer formed using an organometallic compound as a Group III element source material, a p-type impurity source material and ammonia as a Group V element source material, with the hydrogen concentration in the first p-type nitride semiconductor layer being 1×1019 cm?3 or less; and a second p-type nitride semiconductor layer on the first p-type nitride semiconductor layer by formed using an organometallic compound as a Group III element source material, a p-type impurity source material, and ammonia and a hydrazine derivatives as Group V element source materials, with the carbon concentration in the second p-type nitride semiconductor layer being 1×1018 cm?3 or less.Type: ApplicationFiled: March 16, 2009Publication date: September 24, 2009Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Akihito Ohno, Masayoshi Takemi, Nobuyuki Tomita
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Patent number: 7590158Abstract: A first buffer layer (GaAs), a second buffer layer (AlGaAs), and a diffusion suppressing layer consisting of GaAs or AlGaAs are stacked on a GaAs substrate. The structure has a first cladding layer thereon. When AlGaAs is used for the diffusion suppressing layer, the Al ratio of AlGaAs is made smaller than in the second buffer layer. In such a structure, when a window region is formed, the diffusion rate of the impurity (Zn) can be lowered in the diffusion suppressing layer, and the diffusion of the impurity can be stopped at the second buffer layer.Type: GrantFiled: June 22, 2006Date of Patent: September 15, 2009Assignee: Mitsubishi Electric CorporationInventors: Kenichi Ono, Masayoshi Takemi, Harumi Nishiguchi
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Patent number: 7564076Abstract: A laser diode includes a first n-cladding layer disposed on and lattice-matched to an n-semiconductor substrate, wherein the first n-cladding layer is n-AlGaInP or n-GaInP; a second n-cladding layer of n-AlGaAs supported by the first n-cladding layer; and an inserted layer disposed between the first n-cladding layer and the second n-cladding layer, wherein the inserted layer includes the same elements as the first n-cladding layer, the inserted layer has the same composition ratios of Al and Ga (and P) as the first n-cladding layer, and the inserted layer contains a lower composition ratio of In than the first n-cladding layer.Type: GrantFiled: May 6, 2008Date of Patent: July 21, 2009Assignee: MItsubishi Electric CorporationInventors: Yoshihiko Hanamaki, Kenichi Ono, Masayoshi Takemi, Makoto Takada
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Publication number: 20090008659Abstract: A nitride semiconductor stacked structure having good working efficiency includes a p-type nitride semiconductor layer of low resistance, which is formed from an organometallic compound, compounds including Group V elements, including ammonia and a hydrazine derivative, and a p-type impurity material on a substrate. The p-type nitride layer has a carbon concentration not higher than 1×1018 cm?3.Type: ApplicationFiled: December 5, 2007Publication date: January 8, 2009Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Akihito Ohno, Masayoshi Takemi, Nobuyuki Tomita
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Publication number: 20080265275Abstract: A laser diode includes a first n-cladding layer disposed on and lattice-matched to an n-semiconductor substrate, wherein the first n-cladding layer is n-AlGaInP or n-GaInP; a second n-cladding layer of n-AlGaAs supported by the first n-cladding layer; and an inserted layer disposed between the first n-cladding layer and the second n-cladding layer, wherein the inserted layer includes the same elements as the first n-cladding layer, the inserted layer has the same composition ratios of Al and Ga (and P) as the first n-cladding layer, and the inserted layer contains a lower composition ratio of In than the first n-cladding layer.Type: ApplicationFiled: May 6, 2008Publication date: October 30, 2008Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Yoshihiko Hanamaki, Kenichi Ono, Masayoshi Takemi, Makoto Takada
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Patent number: 7436870Abstract: A semiconductor laser device includes: an n-type cladding layer, an active layer, and a p-type cladding layer, each being a III-V group compound semiconductor, supported on a substrate of n-type GaAs, a p-type band discontinuity reduction layer of a III-V group compound semiconductor on the p-type cladding layer, and a p-type GaAs cap layer on the band discontinuity reduction layer. The p-type cladding layer, the p-type band discontinuity reduction layer, and the p-type cap layer are each doped with a p-type dopant which is lower in diffusivity than Zn. The p-type band discontinuity reduction layer has a concentration of a p-type dopant lower in diffusivity than Zn of 2.5×1018 cm?3 or higher to attain desired device characteristics, for example, high power output and efficiency.Type: GrantFiled: February 1, 2005Date of Patent: October 14, 2008Assignee: Mitsubishi Denki Kabushiki KaishaInventors: Kenichi Ono, Masayoshi Takemi
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Patent number: 7394114Abstract: A laser diode includes a first n-cladding layer disposed on and lattice-matched to an n-semiconductor substrate, wherein the first n-cladding layer is n-AlGaInP or n-GaInP; a second n-cladding layer of n-AlGaAs supported by the first n-cladding layer; and an inserted layer disposed between the first n-cladding layer and the second n-cladding layer, wherein the inserted layer includes the same elements as the first n-cladding layer, the inserted layer has the same composition ratios of Al and Ga (and P) as the first n-cladding layer, and the inserted layer contains a lower composition ratio of In than the first n-cladding layer.Type: GrantFiled: October 17, 2006Date of Patent: July 1, 2008Assignee: Mitsubishi Electric CorporationInventors: Yoshihiko Hanamaki, Kenichi Ono, Masayoshi Takemi, Makoto Takada
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Publication number: 20080130697Abstract: A semiconductor laser having a ridge structure, comprises a lower cladding layer, an active layer, and an upper cladding layer that are sequentially arranged and supported by a GaAs semiconductor substrate having a misorientation angle of 7 degrees or more. The active layer is AlGaAs. The upper and lower cladding layers are AlGaAsP and the composition ratio of P in the upper and lower cladding layers is higher than 0 and no more than 0.04.Type: ApplicationFiled: May 3, 2007Publication date: June 5, 2008Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Motoharu MIYASHITA, Akihiro SHIMA, Masayoshi TAKEMI
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Publication number: 20080073660Abstract: A semiconductor laser device comprises an n-type cladding layer, a p-type cladding layer, and an active layer which is sandwiched between the n-type cladding layer and the p-type cladding layer. The p-type cladding layer contains magnesium as a dopant impurity. Further, an n-type diffusion blocking layer of a nitride compound semiconductor material located between the active layer and the p-type cladding layer and is InxAlyGa1?x?yN, where x?0, y?0, and (x+y)<1. The n-type diffusion blocking layer preferably has a concentration of a dopant impurity producing n-type conductivity in a range from 5×1017 cm?3 to 5×1019 cm?3.Type: ApplicationFiled: September 13, 2007Publication date: March 27, 2008Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Akihito Ohno, Masayoshi Takemi, Nobuyuki Tomita
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Publication number: 20080070387Abstract: A technique is provided which enables formation of nitride semiconductor layers with excellent flatness and excellent crystallinity on a gallium nitride substrate (GaN substrate), while improving the producibility of the semiconductor device using the GaN substrate. A gallium nitride substrate is prepared which has an upper surface having an off-angle of not less than 0.1° nor more than 1.0° in a <1-100> direction, with respect to a (0001) plane. Then, a plurality of nitride semiconductor layers including an n-type semiconductor layer are stacked on the upper surface of the gallium nitride substrate to form a semiconductor device such as a semiconductor laser.Type: ApplicationFiled: November 16, 2007Publication date: March 20, 2008Applicant: MITSUBISHI DENKI KABUSHIKI KAISHAInventors: Akihito Ohno, Masayoshi Takemi, Nobuyuki Tomita
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Publication number: 20080054277Abstract: The semiconductor laser device includes an active layer, a p-type cladding layer, and a p-type cap layer. The layers are sequentially stacked so that the semiconductor laser device is provided. The p-type cap layer includes both a p-type dopant and an n-type dopant. In another aspect, the p-type cap layer includes a first layer including a first p-type dopant and a second layer including a second p-type dopant having a diffusion coefficient smaller than that of the first p-type dopant. The first layer is far from the active layer, and the second layer is close to the active layer. In further aspect, the p-type cap layer includes carbon (C) as a p-type dopant. According to these configuration, the p-type dopant can be prevented from being diffused in the active layer and the p-type cladding layer.Type: ApplicationFiled: October 25, 2007Publication date: March 6, 2008Applicant: MITSUBISHI DENKI KABUSHIKI KAISHAInventors: Masayoshi Takemi, Kenichi Ono, Yoshihiko Hanamaki, Chikara Watatani, Tetsuya Yagi, Harumi Nishiguchi, Motoko Sasaki, Shinji Abe, Yasuaki Yoshida
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Publication number: 20070272935Abstract: A laser diode includes a first n-cladding layer disposed on and lattice-matched to an n-semiconductor substrate, wherein the first n-cladding layer is n-AlGaInP or n-GaInP; a second n-cladding layer of n-AlGaAs supported by the first n-cladding layer; and an inserted layer disposed between the first n-cladding layer and the second n-cladding layer, wherein the inserted layer includes the same elements as the first n-cladding layer, the inserted layer has the same composition ratios of Al and Ga (and P) as the first n-cladding layer, and the inserted layer contains a lower composition ratio of In than the first n-cladding layer.Type: ApplicationFiled: October 17, 2006Publication date: November 29, 2007Applicant: MITSUBISHI ELECTRIC CORPORATIONInventors: Yoshihiko HANAMAKI, Kenichi ONO, Masayoshi TAKEMI, Makoto TAKADA