Patents by Inventor Tomoaki KOIZUMI
Tomoaki KOIZUMI 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: 20230283049Abstract: A method for manufacturing a GaN-based surface-emitting laser by an MOVPE includes: growing a first cladding layer with a {0001} growth plane; growing a guide layer on the first cladding layer; forming holes which are two-dimensionally periodically arranged within the guide layer; etching the guide layer by ICP-RIE using a chlorine-based gas and an argon; supplying a gas containing a nitrogen to cause mass-transport, and then supplying the group-III gas for growth, whereby a first embedding layer closing openings of the holes is formed to form a photonic crystal layer; and growing an active layer and a second cladding layer on the first embedding layer, The step includes a step of referring to already-obtained data on a relationship of an attraction voltage and a ratio of gases in the ICP-RIE with a diameter distribution of air holes embedded, and applying the attraction voltage and the ratio to the ICP-RIE.Type: ApplicationFiled: April 21, 2023Publication date: September 7, 2023Applicants: Kyoto University, Stanley Electric Co., Ltd.Inventors: Susumu NODA, Tomoaki KOIZUMI, Kei EMOTO
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Publication number: 20230275398Abstract: A photonic-crystal surface-emitting laser element includes: a first semiconductor layer formed by embedding a photonic crystal layer that includes air holes arranged with two-dimensional periodicity in a formation region in a plane parallel to the photonic crystal layer; an active layer formed on the first semiconductor layer; a second semiconductor layer formed on the active layer; and a mesa portion with a mesa shape formed at a surface of the second semiconductor layer, wherein the mesa portion is located inside the formation region of the air holes when viewed in a direction perpendicular to the photonic crystal layer.Type: ApplicationFiled: July 1, 2021Publication date: August 31, 2023Applicants: KYOTO UNIVERSITY, STANLEY ELECTRIC CO., LTD.Inventors: Susumu NODA, Takuya INOUE, Kei EMOTO, Tomoaki KOIZUMI
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Patent number: 11670910Abstract: A method for manufacturing a GaN-based surface-emitting laser by an MOVPE includes: (a) growing a first cladding layer with a {0001} growth plane; (b) growing a guide layer on the first cladding layer; (c) forming holes which are two-dimensionally periodically arranged within the guide layer; (d) etching the guide layer by ICP-RIE using a chlorine-based gas and an argon; (e) supplying a gas containing a nitrogen to cause mass-transport, and then supplying the group-III gas for growth, whereby a first embedding layer closing openings of the holes is formed to form a photonic crystal layer; and (f) growing an active layer and a second cladding layer on the first embedding layer, The step (d) includes a step of referring to already-obtained data on a relationship of an attraction voltage and a ratio of gases in the ICP-RIE with a diameter distribution of air holes embedded, and applying the attraction voltage and the ratio to the ICP-RIE.Type: GrantFiled: December 16, 2020Date of Patent: June 6, 2023Assignees: KYOTO UNIVERSITY, STANLEY ELECTRIC CO., LTD.Inventors: Susumu Noda, Tomoaki Koizumi, Kei Emoto
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Publication number: 20230127863Abstract: A surface-emitting laser element includes: a first guide layer including a photonic crystal layer that is formed on a c plane of a group-3 nitride semiconductor and includes air holes arranged with two-dimensional periodicity in a plane parallel to the photonic crystal layer, and an embedding layer that is formed on the photonic crystal layer and closes the air holes; an active layer formed on the first guide layer; and a second guide layer formed on the active layer, wherein an air hole set including at least a main air hole and a sub-air hole smaller in size than the main air hole is arranged at each square lattice point in the plane parallel to the photonic crystal layer, and wherein the main air hole has a regular-hexagonal prism shape, a long-hexagonal prism shape, or an elliptic cylindrical shape with a major axis parallel to a <11-20> axis.Type: ApplicationFiled: February 10, 2021Publication date: April 27, 2023Applicants: KYOTO UNIVERSITY, STANLEY ELECTRIC CO., LTD.Inventors: Susumu NODA, Takuya INOUE, Tomoaki KOIZUMI, Kei EMOTO
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Patent number: 11539187Abstract: A surface emission laser formed of a group III nitride semiconductor includes a first conductivity type first clad layer; a first conductivity type first guide layer on the first clad layer; a light-emitting layer on the first guide layer; a second guide layer on the light-emitting layer; and a second conductivity type second clad layer on the second guide layer. The first or second guide layer internally includes voids periodically arranged at square lattice positions with two axes perpendicular to one another as arrangement directions in a surface parallel to the guide layer. The voids have a polygonal prism structure or an oval columnar structure with a long axis and a short axis perpendicular to the long axis in the parallel surface, and the long axis is inclined with respect to one axis among the arrangement directions of the voids.Type: GrantFiled: December 17, 2018Date of Patent: December 27, 2022Assignees: KYOTO UNIVERSITY, STANLEY ELECTRIC CO., LTD.Inventors: Susumu Noda, Yoshinori Tanaka, Menaka De Zoysa, Tomoaki Koizumi, Kei Emoto
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Patent number: 11283243Abstract: A method for manufacturing a surface emitting laser made of a group-III nitride semiconductor by an MOVPE method includes: (a) growing a first cladding layer of a first conductive type on a substrate; (b) growing a first optical guide layer of the first conductive type on the first cladding layer; (c) forming holes having a two-dimensional periodicity in a plane parallel to the first optical guide layer, in the first optical guide layer by etching; (d) supplying a gas containing a group-III material and a nitrogen source and performing growth to form recessed portions having a facet of a predetermined plane direction above openings of the holes, thereby closing the openings of the holes; and (e) planarizing the recessed portions by mass transport, after the openings of the holes have been closed, wherein after the planarizing at least one side surface of the holes is a {10-10} facet.Type: GrantFiled: February 27, 2018Date of Patent: March 22, 2022Assignees: KYOTO UNIVERSITY, STANLEY ELECTRIC CO., LTD.Inventors: Susumu Noda, Yoshinori Tanaka, Menaka De Zoysa, Junichi Sonoda, Tomoaki Koizumi, Kei Emoto
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Publication number: 20210328406Abstract: A surface emitting laser element formed of a group III nitride semiconductor, comprising: a first clad layer of a first conductivity type; a first guide layer of the first conductivity type having a photonic crystal layer formed on the first clad layer including voids disposed having two-dimensional periodicity in a surface parallel to the layer and a first embedding layer formed on the photonic crystal layer; a second embedding layer formed on the first embedding layer by crystal growth; an active layer formed on the second embedding layer; a second guide layer formed on the active layer; and a second clad layer of a second conductivity type formed on the second guide layer, the second conductivity type being a conductivity type opposite to the first conductivity type. The first embedding layer has a surface including pits disposed at surface positions corresponding to the voids.Type: ApplicationFiled: August 29, 2019Publication date: October 21, 2021Applicants: KYOTO UNIVERSITY, STANLEY ELECTRIC CO., LTD.Inventors: Susumu NODA, Yoshinori TANAKA, Menaka DE ZOYSA, Kenji ISHIZAKI, Tomoaki KOIZUMI, Kei EMOTO
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Publication number: 20210184431Abstract: A method for manufacturing a GaN-based surface-emitting laser by an MOVPE includes: (a) growing a first cladding layer with a {0001} growth plane; (b) growing a guide layer on the first cladding layer; (c) forming holes which are two-dimensionally periodically arranged within the guide layer; (d) etching the guide layer by ICP-RIE using a chlorine-based gas and an argon; (e) supplying a gas containing a nitrogen to cause mass-transport, and then supplying the group-III gas for growth, whereby a first embedding layer closing openings of the holes is formed to form a photonic crystal layer; and (f) growing an active layer and a second cladding layer on the first embedding layer, The step (d) includes a step of referring to already-obtained data on a relationship of an attraction voltage and a ratio of gases in the ICP-RIE with a diameter distribution of air holes embedded, and applying the attraction voltage and the ratio to the ICP-RIE.Type: ApplicationFiled: December 16, 2020Publication date: June 17, 2021Applicants: Kyoto University, Stanley Electric Co., Ltd.Inventors: Susumu NODA, Tomoaki KOIZUMI, Kei EMOTO
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Publication number: 20210184430Abstract: A method for manufacturing a GaN-based surface-emitting laser by an MOVPE includes: (a) growing a first cladding layer with a {0001} growth plane; (b) growing a guide layer on the first cladding layer; (c) forming holes in a surface of the guide layer by etching, the holes being two-dimensionally periodically arranged within a plane parallel to the guide layer; (d) etching the guide layer by using an etchant having selectivity to the {0001} plane and a {10-10} plane of the guide layer; (e) supplying a gas containing a nitrogen source to cause mass transport without supplying a group-III material gas, and then supplying the group-III material gas for growth, whereby a first embedding layer closing openings of the holes is formed to form a photonic crystal layer; and (f) growing an active layer and a second cladding layer in this order on the first embedding layer.Type: ApplicationFiled: December 16, 2020Publication date: June 17, 2021Applicants: Kyoto University, Stanley Electric Co., Ltd.Inventors: Susumu NODA, Tomoaki KOIZUMI, Kei EMOTO
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Publication number: 20210013700Abstract: A surface emission laser formed of a group III nitride semiconductor includes a first conductivity type first clad layer; a first conductivity type first guide layer on the first clad layer; a light-emitting layer on the first guide layer; a second guide layer on the light-emitting layer; and a second conductivity type second clad layer on the second guide layer. The first or second guide layer internally includes voids periodically arranged at square lattice positions with two axes perpendicular to one another as arrangement directions in a surface parallel to the guide layer. The voids have a polygonal prism structure or an oval columnar structure with a long axis and a short axis perpendicular to the long axis in the parallel surface, and the long axis is inclined with respect to one axis among the arrangement directions of the voids.Type: ApplicationFiled: December 17, 2018Publication date: January 14, 2021Applicants: Kyoto University, Stanley Electric Co., Ltd.Inventors: Susumu NODA, Yoshinori TANAKA, Menaka DE ZOYSA, Tomoaki KOIZUMI, Kei EMOTO
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Publication number: 20200251887Abstract: A method for manufacturing a surface emitting laser made of a group-III nitride semiconductor by an MOVPE method includes: (a) of growing a first cladding layer of a first conductive type on a substrate; (b) of growing a first optical guide layer of the first conductive type on the first cladding layer; (c) of forming holes having a two-dimensional periodicity in a plane parallel to the first optical guide layer, in the first optical guide layer by etching; (d) supplying a gas containing a group-III material and a nitrogen source and performing growth to form recessed portions having a facet of a predetermined plane direction above openings of the holes, thereby closing the openings of the holes; and (e) of planarizing the recessed portions by mass transport, after the openings of the holes have been closed, wherein after said the planarizing, at least one side surface of the holes is a {10-10} facet.Type: ApplicationFiled: February 27, 2018Publication date: August 6, 2020Applicants: KYOTO UNIVERSITY, STANLEY ELECTRIC CO., LTD.Inventors: Susumu NODA, Yoshinori TANAKA, Menaka DE ZOYSA, Junichi SONODA, Tomoaki KOIZUMI, Kei EMOTO