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).
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Patent number: 9112096Abstract: 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: GrantFiled: July 1, 2013Date of Patent: August 18, 2015Assignee: MITSUBISHI CHEMICAL CORPORATIONInventors: Kenji Fujito, Kazumasa Kiyomi
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Publication number: 20130320394Abstract: 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: ApplicationFiled: July 1, 2013Publication date: December 5, 2013Applicant: Mitsubishi Chemical CorporationInventors: Kenji Fujito, Kazumasa Kiyomi
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Publication number: 20120305983Abstract: 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: ApplicationFiled: August 10, 2012Publication date: December 6, 2012Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Kenji Fujito, Kazumasa Kiyomi
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Patent number: 8269251Abstract: 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: GrantFiled: May 16, 2008Date of Patent: September 18, 2012Assignee: Mitsubishi Chemical CorporationInventors: Kenji Fujito, Kazumasa Kiyomi
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Publication number: 20120112320Abstract: 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: ApplicationFiled: December 1, 2011Publication date: May 10, 2012Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Shuichi KUBO, Kenji Shimoyama, Kazumasa Kiyomi, Kenji Fujito, Yutaka Mikawa
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Patent number: 8142566Abstract: 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: GrantFiled: August 5, 2005Date of Patent: March 27, 2012Assignee: Mitsubishi Chemical CorporationInventors: Kazumasa Kiyomi, Hirobumi Nagaoka, Hirotaka Oota, Isao Fujimura
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Patent number: 7794541Abstract: 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: GrantFiled: March 8, 2007Date of Patent: September 14, 2010Assignees: Tohoku University, Mitsubishi Chemical CorporationInventors: Hiroyuki Shibata, Yoshio Waseda, Kenji Shimoyama, Kazumasa Kiyomi, Hirobumi Nagaoka
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Publication number: 20100162945Abstract: A method to make gallium nitride-based material by Hydride Vapor Phase Epitaxial Growth is provided.Type: ApplicationFiled: March 8, 2010Publication date: July 1, 2010Applicants: Tohoku University, Mitsubishi Chemical CorporationInventors: Hiroyuki Shibata, Yoshio Waseda, Kenji Shimoyama, Kazumasa Kiyomi, Hirobumi Nagaoka
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Publication number: 20100148212Abstract: 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: ApplicationFiled: May 16, 2008Publication date: June 17, 2010Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Kenji Fujito, Kazumasa Kiyomi
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Publication number: 20100140536Abstract: 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: ApplicationFiled: February 17, 2010Publication date: June 10, 2010Applicants: Tohoku University, Mitsubishi Chemical CorporationInventors: Hiroyuki SHIBATA, Yoshio Waseda, Kenji Shimoyama, Kazumasa Kiyomi, Hirobumi Nagaoka
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Publication number: 20090081110Abstract: 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: ApplicationFiled: March 8, 2007Publication date: March 26, 2009Applicants: Tohoku University, MITSUBISHI CHEMICAL CORPORATIONInventors: Hiroyuki Shibata, Yoshio Waseda, Kenji Shimoyama, Kazumasa Kiyomi, Hirobumi Nagaoka
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Publication number: 20090026488Abstract: 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: ApplicationFiled: February 8, 2006Publication date: January 29, 2009Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Kazumasa Kiyomi, Hideyoshi Horie, Toshio Ishiwatari, Isao Fujimura
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Publication number: 20080308812Abstract: 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: ApplicationFiled: August 5, 2005Publication date: December 18, 2008Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Kazumasa Kiyomi, Hirobumi Nagaoka, Hirotaka Oota, Isao Fujimura
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Patent number: 6807213Abstract: 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: GrantFiled: February 23, 2000Date of Patent: October 19, 2004Assignee: Mitsubishi Chemical CorporationInventors: Kenji Shimoyama, Nobuyuki Hosoi, Kazumasa Kiyomi, Yoshihito Sato, Satosi Kikuchi
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Patent number: 6744066Abstract: 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: GrantFiled: February 20, 2001Date of Patent: June 1, 2004Assignee: Mitsubishi Chemical CorporationInventors: Kenji Shimoyama, Kazumasa Kiyomi, Hideki Gotoh, Satoru Nagao
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Patent number: 6707071Abstract: 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: GrantFiled: March 13, 2002Date of Patent: March 16, 2004Assignee: Mitsubishi Chemical CorporationInventors: Makiko Hashimoto, Nobuyuki Hosoi, Kenji Shimoyama, Katsushi Fujii, Yoshihito Sato, Kazumasa Kiyomi
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Patent number: 6589807Abstract: 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: GrantFiled: May 31, 2001Date of Patent: July 8, 2003Assignee: Mitsubishi Chemical CorporationInventors: Kenji Shimoyama, Kazumasa Kiyomi, Hideki Gotoh, Satoru Nagao
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Publication number: 20020125488Abstract: 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: ApplicationFiled: March 13, 2002Publication date: September 12, 2002Applicant: Mitsubishi Chemical CorporationInventors: Makiko Hashimoto, Nobuyuki Hosoi, Kenji Shimoyama, Katsushi Fujii, Yoshihito Sato, Kazumasa Kiyomi
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Patent number: 6387721Abstract: 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: GrantFiled: September 24, 1999Date of Patent: May 14, 2002Assignee: Mitsubishi Chemical CorporationInventors: Makiko Hashimoto, Nobuyuki Hosoi, Kenji Shimoyama, Katsushi Fujii, Yoshihito Sato, Kazumasa Kiyomi
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Publication number: 20020014622Abstract: 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: ApplicationFiled: May 31, 2001Publication date: February 7, 2002Applicant: MITSUBISHI CHEMICAL CORPORATIONInventors: Kenji Shimoyama, Kazumasa Kiyomi, Hideki Gotoh, Satoru Nagao