Patents by Inventor Yasufumi Fujiwara
Yasufumi Fujiwara 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: 20220278249Abstract: Provided are: a near infrared light-emitting semiconductor element that does not contain any harmful elements and that makes it possible to obtain near infrared light of a stable wavelength in a narrow band regardless of the operating environment; and a method for producing the near infrared light-emitting semiconductor element. GaN is used in the method for producing a near infrared light-emitting semiconductor element, and an active layer added in order to substitute Tm with Ga is formed on GaN in a reaction container at a growth rate of 0.1-30 ?m/h without removal from said reaction container using an organometallic vapor phase growth method under temperature conditions of 600-1400° C. in a series of formation steps including formation of a p-type layer and an n-type layer. GaN is used in the near infrared light-emitting semiconductor element, and said near infrared light-emitting semiconductor element includes an active layer sandwiched between an n-type layer and a p-type layer on a substrate.Type: ApplicationFiled: February 28, 2022Publication date: September 1, 2022Applicant: OSAKA UNIVERSITYInventors: Shuhei ICHIKAWA, Naoki YOSHIOKA, Yasufumi FUJIWARA, Jun TATEBAYASHI
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Publication number: 20210399175Abstract: The purpose of the present invention is to provide a technique of manufacturing a nitride semiconductor layer with which, when producing a semiconductor device by forming a nitride semiconductor layer on off-angle inclined substrate, it is possible to stably supply high-quality semiconductor devices by preventing occurrence of a macro step using a material that is not likely to occur lattice strains or crystal defects by mixing with GaN and does not require continuous addition; and provided is a nitride semiconductor device which comprises a nitride semiconductor layer formed on a substrate, wherein the substrate is inclined at an off angle, a rare earth element-added nitride layer to which a rare earth element is added is formed on the substrate as a primed layer, and a nitride semiconductor layer is formed on the rare earth element-added nitride layer.Type: ApplicationFiled: August 30, 2019Publication date: December 23, 2021Applicant: OSAKA UNIVERSITYInventors: Shuhei ICHIKAWA, Yasufumi FUJIWARA, Jun TATEBAYASHI
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Patent number: 11133435Abstract: Provided is a technique for manufacturing a nitride semiconductor substrate with which it is possible to manufacture a nitride semiconductor substrate having sufficiently reduced dislocation density with a large area even if manufactured on an inexpensive substrate made of sapphire, etc. A nitride semiconductor substrate in which a nitride semiconductor layer formed on a substrate is formed by laminating an undoped nitride layer and a rare earth element-added nitride layer to which a rare earth element is added as a doping material, and the dislocation density is of the order of 106 cm?2 or less.Type: GrantFiled: November 20, 2017Date of Patent: September 28, 2021Assignee: OSAKA UNIVERSITYInventors: Yasufumi Fujiwara, Wanxin Zhu, Atsushi Koizumi, Brandon Mitchell, Tom Gregorkiewicz
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Publication number: 20210296528Abstract: Provided is a display device including a light emitting unit that can emit a plurality of types of light having different wavelengths to the outside at a desired ratio with high intensity without increasing manufacturing costs in proportion to a number of pixels even when the number of pixels increases. Provided is a display device including a light emitting unit in which a plurality of types of PiN junction-type light emitting diodes that emit light having different wavelengths are arranged on the same substrate, and at least one type among the plurality of types of light emitting diodes has an active layer containing a rare earth element. Provided is a display device in which a plurality of types of light emitting diodes are sequentially stacked on the surface of a substrate, and a light emitting layer for one color is formed to overlap at least a portion of a light emitting layer for another color.Type: ApplicationFiled: June 9, 2021Publication date: September 23, 2021Applicant: OSAKA UNIVERSITYInventors: Yasufumi FUJIWARA, Takeshi UENOYAMA, Jun TATEBAYASHI, Shuhei ICHIKAWA
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Patent number: 11075322Abstract: Provided is a technique for manufacturing a semiconductor light-emitting element for which it is possible to dramatically increase light emission efficiency to a greater degree than in the past. An AlInN film provided on a GaN epitaxial film that is formed on a substrate, wherein: the AlInN film is formed by lamination of AlInN layers; between the laminated AlInN layers, there is provided a cap layer that comprises GaN, AlN, or AlGaN, and has a thickness of 0.1-10 nm; a super lattice structure is formed; the total thickness exceeds 200 nm; and the root-mean-square height RMS is 3 nm or less. A method for forming an AlInN film, the method being such that: a step for forming an AlInN layer is repeated a plurality of times, said step involving using any of an organometallic vapor phase growth method, a molecular beam epitaxy method, and a sputtering method to form the AlInN layer to a thickness of 200 nm or less by epitaxial growth in an atmosphere of 700-850° C.Type: GrantFiled: February 26, 2018Date of Patent: July 27, 2021Assignee: OSAKA UNIVERSITYInventors: Yasufumi Fujiwara, Tomohiro Inaba
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Publication number: 20210091268Abstract: A color tunable light emission diode in which the color tone of the emission color changes by controlling the injection current, which has an active layer sandwiched between a p-type layer and an n-type layer on a substrate, and the active color layer is formed by doping Eu and Mg to an AlGaInN-based material which is GaN, InN, AlN or a mixed crystal of any two or more of them; and a micro LED display, wherein its display unit is formed by integrating image pixels having the above color tunable light emission diode are provided; and a light emitting semiconductor device technology capable of providing an ultra-small and high definition micro LED display can be provided.Type: ApplicationFiled: April 14, 2020Publication date: March 25, 2021Inventors: Volkmar Dierolf, Brandon Mitchell, Ruoqiao Wei, Yasufumi Fujiwara, Tomasz Gregorkiewicz, Shuhei Ichikawa, Jun Tatebayashi, Dolf Timmerman
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Publication number: 20200058828Abstract: Provided is a technique for manufacturing a semiconductor light-emitting element for which it is possible to dramatically increase light emission efficiency to a greater degree than in the past. An AlInN film provided on a GaN epitaxial film that is formed on a substrate, wherein: the AlInN film is formed by lamination of AlInN layers; between the laminated AlInN layers, there is provided a cap layer that comprises GaN, AlN, or AlGaN, and has a thickness of 0.1-10 nm; a super lattice structure is formed; the total thickness exceeds 200 nm; and the root-mean-square height RMS is 3 nm or less. A method for forming an AlInN film, the method being such that: a step for forming an AlInN layer is repeated a plurality of times, said step involving using any of an organometallic vapor phase growth method, a molecular beam epitaxy method, and a sputtering method to form the AlInN layer to a thickness of 200 nm or less by epitaxial growth in an atmosphere of 700-850° C.Type: ApplicationFiled: February 26, 2018Publication date: February 20, 2020Applicant: OSAKA UNIVERSITYInventors: Yasufumi FUJIWARA, Tomohiro INABA
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Publication number: 20190280156Abstract: Provided is a technique for manufacturing a nitride semiconductor substrate with which it is possible to manufacture a nitride semiconductor substrate having sufficiently reduced dislocation density with a large area even if manufactured on an inexpensive substrate made of sapphire, etc. A nitride semiconductor substrate in which a nitride semiconductor layer formed on a substrate is formed by laminating an undoped nitride layer and a rare earth element-added nitride layer to which a rare earth element is added as a doping material, and the dislocation density is of the order of 106 cm-2 or less.Type: ApplicationFiled: November 20, 2017Publication date: September 12, 2019Applicant: OSAKA UNIVERSITYInventors: Yasufumi FUJIWARA, Wanxin ZHU, Atsushi KOIZUMI, Brandon MITCHELL, Tom GREGORKIEWICZ
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Patent number: 9455376Abstract: A production method of a substrate for nitride semiconductor device comprising a mask formation step of using a metal nitride as a base material and forming a mask having a prescribed shape on the above-described base material, a three-dimensional structure growth step of growing a three-dimensional structure made of the same material as the base material on the base material having the mask formed thereon using a selective growth technique so that a layer having a higher index plane is formed on the lateral face, and an active layer growth step of growing an active layer containing a rare earth element on the lateral face of the above-described three-dimensional structure using an organometallic vapor phase epitaxial method.Type: GrantFiled: August 1, 2013Date of Patent: September 27, 2016Assignee: OSAKA UNIVERSITYInventors: Yasufumi Fujiwara, Atsushi Koizumi, Yoshikazu Terai
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Publication number: 20150214434Abstract: A production method of a substrate for nitride semiconductor device comprising a mask formation step of using a metal nitride as a base material and forming a mask having a prescribed shape on the above-described base material, a three-dimensional structure growth step of growing a three-dimensional structure made of the same material as the base material on the base material having the mask formed thereon using a selective growth technique so that a layer having a higher index plane is formed on the lateral face, and an active layer growth step of growing an active layer containing a rare earth element on the lateral face of the above-described three-dimensional structure using an organometallic vapor phase epitaxial method.Type: ApplicationFiled: August 1, 2013Publication date: July 30, 2015Applicant: OSAKA UNIVERSITYInventors: Yasufumi Fujiwara, Atsushi Koizumi, Yoshikazu Terai
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Patent number: 8409897Abstract: Disclosed are: an environmentally friendly red light-emitting semiconductor element which operates at low voltage, while having sufficient luminous efficiency and sufficient luminous intensity; and a method for manufacturing the same. Specifically disclosed is a method for manufacturing a red light-emitting semiconductor element, wherein an active layer is formed between a p-type layer and an n-type layer in a sequence of the formation steps of the p-type layer and the n-type layer, said active layer being obtained by adding Eu or Pr into GaN, InN, AlN or a mixed crystal thereof by substituting Ga, In or Al with Eu or Pr, using an organic metal vapor phase deposition method under specific temperature conditions in a site wherein light having a wavelength of 618-623 nm can be emitted. Also specifically disclosed is a red light-emitting semiconductor element which is manufactured by the method for manufacturing a red light-emitting semiconductor element.Type: GrantFiled: April 28, 2010Date of Patent: April 2, 2013Assignee: Osaka UniversityInventors: Atsushi Nishikawa, Yasufumi Fujiwara, Yoshikazu Terai, Takashi Kawasaki, Naoki Furukawa
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Publication number: 20120077299Abstract: Disclosed are: an environmentally friendly red light-emitting semiconductor element which operates at low voltage, while having sufficient luminous efficiency and sufficient luminous intensity; and a method for manufacturing the same. Specifically disclosed is a method for manufacturing a red light-emitting semiconductor element, wherein an active layer is formed between a p-type layer and an n-type layer in a sequence of the formation steps of the p-type layer and the n-type layer, said active layer being obtained by adding Eu or Pr into GaN, InN, AlN or a mixed crystal thereof by substituting Ga, In or Al with Eu or Pr, using an organic metal vapor phase deposition method under specific temperature conditions in a site wherein light having a wavelength of 618-623 nm can be emitted. Also specifically disclosed is a red light-emitting semiconductor element which is manufactured by the method for manufacturing a red light-emitting semiconductor element.Type: ApplicationFiled: April 28, 2010Publication date: March 29, 2012Inventors: Atsushi Nishikawa, Yasufumi Fujiwara, Yoshikazu Terai, Takashi Kawasaki, Naoki Furukawa
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Publication number: 20060071218Abstract: A semiconductor multi-layered structure (1) having non-uniform quantum dots formed without requiring lattice strain is of a double hetero junction structure in which an active layer (3) has clad layers (5, 6, 16) laid on its opposite sides, wherein the clad layers are larger in forbidden band than the active layer (3), and the active layer (3) includes at least one layer of non-uniform quantum dots (2) formed without requiring lattice strain and wherein the non-uniform quantum dots in the layer (2) are composed of compound semiconductor material and different from one another in either size or material composition or both. A light emitting diode (15, 15?), a semiconductor laser diode (20) and a semiconductor light amplifier (30) are also provided, each having a semiconductor multi-layered structure (1, 1?) with non-uniform quantum dots. They can emit or amplify light wide in range of wavelengths.Type: ApplicationFiled: June 13, 2003Publication date: April 6, 2006Applicant: JAPAN SCIENCE AND TECHNOLOGY AGENCYInventors: Yoshikazu Takeda, Yasufumi Fujiwara, Ryo Oga, WooSik Lee