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).

  • Publication number: 20220278249
    Abstract: 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: Application
    Filed: February 28, 2022
    Publication date: September 1, 2022
    Applicant: OSAKA UNIVERSITY
    Inventors: Shuhei ICHIKAWA, Naoki YOSHIOKA, Yasufumi FUJIWARA, Jun TATEBAYASHI
  • Publication number: 20210399175
    Abstract: 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: Application
    Filed: August 30, 2019
    Publication date: December 23, 2021
    Applicant: OSAKA UNIVERSITY
    Inventors: Shuhei ICHIKAWA, Yasufumi FUJIWARA, Jun TATEBAYASHI
  • Patent number: 11133435
    Abstract: 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: Grant
    Filed: November 20, 2017
    Date of Patent: September 28, 2021
    Assignee: OSAKA UNIVERSITY
    Inventors: Yasufumi Fujiwara, Wanxin Zhu, Atsushi Koizumi, Brandon Mitchell, Tom Gregorkiewicz
  • Publication number: 20210296528
    Abstract: 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: Application
    Filed: June 9, 2021
    Publication date: September 23, 2021
    Applicant: OSAKA UNIVERSITY
    Inventors: Yasufumi FUJIWARA, Takeshi UENOYAMA, Jun TATEBAYASHI, Shuhei ICHIKAWA
  • Patent number: 11075322
    Abstract: 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: Grant
    Filed: February 26, 2018
    Date of Patent: July 27, 2021
    Assignee: OSAKA UNIVERSITY
    Inventors: Yasufumi Fujiwara, Tomohiro Inaba
  • Publication number: 20210091268
    Abstract: 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: Application
    Filed: April 14, 2020
    Publication date: March 25, 2021
    Inventors: Volkmar Dierolf, Brandon Mitchell, Ruoqiao Wei, Yasufumi Fujiwara, Tomasz Gregorkiewicz, Shuhei Ichikawa, Jun Tatebayashi, Dolf Timmerman
  • Publication number: 20200058828
    Abstract: 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: Application
    Filed: February 26, 2018
    Publication date: February 20, 2020
    Applicant: OSAKA UNIVERSITY
    Inventors: Yasufumi FUJIWARA, Tomohiro INABA
  • Publication number: 20190280156
    Abstract: 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: Application
    Filed: November 20, 2017
    Publication date: September 12, 2019
    Applicant: OSAKA UNIVERSITY
    Inventors: Yasufumi FUJIWARA, Wanxin ZHU, Atsushi KOIZUMI, Brandon MITCHELL, Tom GREGORKIEWICZ
  • Patent number: 9455376
    Abstract: 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: Grant
    Filed: August 1, 2013
    Date of Patent: September 27, 2016
    Assignee: OSAKA UNIVERSITY
    Inventors: Yasufumi Fujiwara, Atsushi Koizumi, Yoshikazu Terai
  • Publication number: 20150214434
    Abstract: 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: Application
    Filed: August 1, 2013
    Publication date: July 30, 2015
    Applicant: OSAKA UNIVERSITY
    Inventors: Yasufumi Fujiwara, Atsushi Koizumi, Yoshikazu Terai
  • Patent number: 8409897
    Abstract: 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: Grant
    Filed: April 28, 2010
    Date of Patent: April 2, 2013
    Assignee: Osaka University
    Inventors: Atsushi Nishikawa, Yasufumi Fujiwara, Yoshikazu Terai, Takashi Kawasaki, Naoki Furukawa
  • Publication number: 20120077299
    Abstract: 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: Application
    Filed: April 28, 2010
    Publication date: March 29, 2012
    Inventors: Atsushi Nishikawa, Yasufumi Fujiwara, Yoshikazu Terai, Takashi Kawasaki, Naoki Furukawa
  • Publication number: 20060071218
    Abstract: 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: Application
    Filed: June 13, 2003
    Publication date: April 6, 2006
    Applicant: JAPAN SCIENCE AND TECHNOLOGY AGENCY
    Inventors: Yoshikazu Takeda, Yasufumi Fujiwara, Ryo Oga, WooSik Lee