Patents by Inventor Hiroaki Okagawa

Hiroaki Okagawa 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).

  • Patent number: 8946772
    Abstract: A substrate for epitaxial growth of the present invention comprises: a single crystal part comprising a material different from a GaN-based semiconductor at least in a surface layer part; and an uneven surface, as a surface for epitaxial growth, comprising a plurality of convex portions arranged so that each of the convex portions has three other closest convex portions in directions different from each other by 120 degrees and a plurality of growth spaces, each of which is surrounded by six of the convex portions, wherein the single crystal part is exposed at least on the growth space, which enables a c-axis-oriented GaN-based semiconductor crystal to grow from the growth space.
    Type: Grant
    Filed: February 13, 2009
    Date of Patent: February 3, 2015
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Hiroaki Okagawa, Hiromitsu Kudo, Teruhisa Nakai, Seong-Jin Kim
  • Patent number: 8829778
    Abstract: A white light-emitting semiconductor device having improved reproducibility of bright red. The device outputs light having a blue component, a green component, and a red component. Each of the light components (blue, green, and red) is based on a light-emitting semiconductor element and/or a phosphor that absorbs light emitted by a light-emitting semiconductor element and emits light through wavelength conversion. The outputted light has a spectrum which has a maximum wavelength in the range of 615-645 nm, and the intensity at a wavelength of 580 nm of the outputted light, which has been normalized with respect to luminous flux, is 80-100% of the intensity at a wavelength of 580 nm of standard light for color rendering evaluation, which has been normalized with respect to luminous flux.
    Type: Grant
    Filed: September 30, 2013
    Date of Patent: September 9, 2014
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Hiroaki Sakuta, Kazuhiko Kagawa, Yoshihito Satou, Hiroaki Okagawa, Shin Hiraoka
  • Patent number: 8716728
    Abstract: A nitride semiconductor light-emitting diode element 1 includes a nitride semiconductor layer 12 having a bottom surface and an upper surface and containing a light emitting layer 12b inside, and a supporting substrate 11 made from a metal is bonded to the bottom surface of the nitride semiconductor layer 12. A light reflecting depression A1 to reflect light generated in the light emitting layer 12b is formed in the bottom surface of the nitride semiconductor layer 12. According to the nitride semiconductor light-emitting diode element 1, since the light generated from the light emitting layer 12b and propagated in the nitride semiconductor layer 12 in a layer direction is reflected by the light reflecting depression A1 and its travel direction is changed, the ratio of the light incident upon the upper surface of the nitride semiconductor layer 12 within a critical angle is increased.
    Type: Grant
    Filed: October 19, 2007
    Date of Patent: May 6, 2014
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Hiromitsu Kudo, Hirokazu Taniguchi, Hiroaki Okagawa, Shin Hiraoka, Takahide Joichi, Toshihiko Shima
  • Publication number: 20140042896
    Abstract: A white light-emitting semiconductor device having improved reproducibility of bright red. The device outputs light having a blue component, a green component, and a red component. Each of the light components (blue, green, and red) is based on a light-emitting semiconductor element and/or a phosphor that absorbs light emitted by a light-emitting semiconductor element and emits light through wavelength conversion. The outputted light has a spectrum which has a maximum wavelength in the range of 615-645 nm, and the intensity at a wavelength of 580 nm of the outputted light, which has been normalized with respect to luminous flux, is 80-100% of the intensity at a wavelength of 580 nm of standard light for color rendering evaluation, which has been normalized with respect to luminous flux.
    Type: Application
    Filed: September 30, 2013
    Publication date: February 13, 2014
    Applicant: Mitsubishi Chemical Corporation
    Inventors: Hiroaki SAKUTA, Kazuhiko Kagawa, Yoshihito Satou, Hiroaki Okagawa, Shin Hiraoka
  • Patent number: 8581488
    Abstract: A white light-emitting semiconductor device having improved reproducibility of bright red. The device outputs light having a blue component, a green component, and a red component. Each of the light components (blue, green, and red) consists of a light-emitting semiconductor element and/or a phosphor that absorbs light emitted by a light-emitting semiconductor element and emits light through wavelength conversion. The outputted light has a spectrum which has a maximum wavelength in the range of 615-645 nm, and the intensity at a wavelength of 580 nm of the outputted light, which has been normalized with respect to luminous flux, is 80-100% of the intensity at a wavelength of 580 nm of standard light for color rendering evaluation, which has been normalized with respect to luminous flux.
    Type: Grant
    Filed: November 9, 2011
    Date of Patent: November 12, 2013
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Hiroaki Sakuta, Kazuhiko Kagawa, Yoshihito Satou, Hiroaki Okagawa, Shin Hiraoka
  • Patent number: 8455886
    Abstract: A light emitting device is constituted by flip-chip mounting a GaN-based LED chip. The GaN-based LED chip includes a light-transmissive substrate and a GaN-based semiconductor layer formed on the light-transmissive substrate, wherein the GaN-based semiconductor layer has a laminate structure containing an n-type layer, a light emitting layer and a p-type layer in this order from the light-transmissive substrate side, wherein a positive electrode is formed on the p-type layer, the electrode containing a light-transmissive electrode of an oxide semiconductor and a positive contact electrode electrically connected to the light-transmissive electrode, and the area of the positive contact electrode is half or less of the area of the upper surface of the p-type layer.
    Type: Grant
    Filed: March 13, 2012
    Date of Patent: June 4, 2013
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Takahide Joichi, Hiroaki Okagawa, Shin Hiraoka, Toshihiko Shima, Hirokazu Taniguchi
  • Publication number: 20120175669
    Abstract: A light emitting device is constituted by flip-chip mounting a GaN-based LED chip. The GaN-based LED chip includes a light-transmissive substrate and a GaN-based semiconductor layer formed on the light-transmissive substrate, wherein the GaN-based semiconductor layer has a laminate structure containing an n-type layer, a light emitting layer and a p-type layer in this order from the light-transmissive substrate side, wherein a positive electrode is formed on the p-type layer, the electrode containing a light-transmissive electrode of an oxide semiconductor and a positive contact electrode electrically connected to the light-transmissive electrode, and the area of the positive contact electrode is half or less of the area of the upper surface of the p-type layer.
    Type: Application
    Filed: March 13, 2012
    Publication date: July 12, 2012
    Inventors: Takahide Joichi, Hiroaki Okagawa, Shin Hiraoka, Toshihiko Shima, Hirokazu Taniguchi
  • Publication number: 20120171796
    Abstract: A first conductive film 104-1 of a light-transmissive conductive oxide film 104 and a positive pad electrode 105 are electrically connected through a second conductive film 104-2 of the light-transmissive conductive oxide film 104 in a GaN-based LED element 100. A contact resistance of the light-transmissive conductive oxide film 104 with a p-type layer 102-3 in a first contact portion 104A is lower than in a second contact portion 104B, so that a current supplied from the positive pad electrode 105 to the p-type layer 102-3 through the conductive oxide film 104 flows to the p-type layer 102-3 mainly through the first contact portion 104A.
    Type: Application
    Filed: March 13, 2012
    Publication date: July 5, 2012
    Inventors: Shin Hiraoka, Hiroaki Okagawa, Takahide Joichi
  • Publication number: 20120112626
    Abstract: A white light-emitting semiconductor device having improved reproducibility of bright red. The device outputs light having a blue component, a green component, and a red component. Each of the light components (blue, green, and red) consists of a light-emitting semiconductor element and/or a phosphor that absorbs light emitted by a light-emitting semiconductor element and emits light through wavelength conversion. The outputted light has a spectrum which has a maximum wavelength in the range of 615-645 nm, and the intensity at a wavelength of 580 nm of the outputted light, which has been normalized with respect to luminous flux, is 80-100% of the intensity at a wavelength of 580 nm of standard light for color rendering evaluation, which has been normalized with respect to luminous flux.
    Type: Application
    Filed: November 9, 2011
    Publication date: May 10, 2012
    Applicant: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Hiroaki SAKUTA, Kazuhiko KAGAWA, Yoshihito Satou, Hiroaki Okagawa, Shin Hiraoka
  • Patent number: 8158994
    Abstract: A first conductive film 104-1 of a light-transmissive conductive oxide film 104 and a positive pad electrode 105 are electrically connected through a second conductive film 104-2 of the light-transmissive conductive oxide film 104 in a GaN-based LED element 100. A contact resistance of the light-transmissive conductive oxide film 104 with a p-type layer 102-3 in a first contact portion 104A is lower than in a second contact portion 104B, so that a current supplied from the positive pad electrode 105 to the p-type layer 102-3 through the conductive oxide film 104 flows to the p-type layer 102-3 mainly through the first contact portion 104A.
    Type: Grant
    Filed: February 20, 2008
    Date of Patent: April 17, 2012
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Shin Hiraoka, Hiroaki Okagawa, Takahide Joichi
  • Patent number: 8158990
    Abstract: A light emitting device is constituted by flip-chip mounting a GaN-based LED chip. The GaN-based LED chip includes a light-transmissive substrate and a GaN-based semiconductor layer formed on the light-transmissive substrate, wherein the GaN-based semiconductor layer has a laminate structure containing an n-type layer, a light emitting layer and a p-type layer in this order from the light-transmissive substrate side, wherein a positive electrode is formed on the p-type layer, the electrode containing a light-transmissive electrode of an oxide semiconductor and a positive contact electrode electrically connected to the light-transmissive electrode, and the area of the positive contact electrode is half or less of the area of the upper surface of the p-type layer.
    Type: Grant
    Filed: October 5, 2007
    Date of Patent: April 17, 2012
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Takahide Joichi, Hiroaki Okagawa, Shin Hiraoka, Toshihiko Shima, Hirokazu Taniguchi
  • Publication number: 20110260196
    Abstract: Provided is a GaN-based LED element having a novel structure for improving output by increasing light extraction efficiency.
    Type: Application
    Filed: June 30, 2011
    Publication date: October 27, 2011
    Applicant: Mitsubishi Chemical Corporation
    Inventors: Hiroaki OKAGAWA, Shin Hiraoka, Takahide Jouichi, Toshihiko Shima
  • Patent number: 8012783
    Abstract: The object of the present invention is to provide a semiconductor element containing an n-type gallium nitride based compound semiconductor and a novel electrode that makes an ohmic contact with the semiconductor. The semiconductor element of the present invention has an n-type Gallium nitride based compound semiconductor and an electrode that forms an ohmic contact with the semiconductor, wherein the electrode has a TiW alloy layer to be in contact with the semiconductor. According to a preferable embodiment, the above-mentioned electrode can also serve as a contact electrode. According to a preferable embodiment, the above-mentioned electrode is superior in the heat resistance. Moreover, a production method of the semiconductor element is also provided.
    Type: Grant
    Filed: April 4, 2006
    Date of Patent: September 6, 2011
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Tsuyoshi Takano, Takahide Joichi, Hiroaki Okagawa
  • Publication number: 20110198560
    Abstract: A substrate for epitaxial growth of the present invention comprises: a single crystal part comprising a material different from a GaN-based semiconductor at least in a surface layer part; and an uneven surface, as a surface for epitaxial growth, comprising a plurality of convex portions arranged so that each of the convex portions has three other closest convex portions in directions different from each other by 120 degrees and a plurality of growth spaces, each of which is surrounded by six of the convex portions, wherein the single crystal part is exposed at least on the growth space, which enables a c-axis-oriented GaN-based semiconductor crystal to grow from the growth space.
    Type: Application
    Filed: February 13, 2009
    Publication date: August 18, 2011
    Applicant: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Hiroaki Okagawa, Hiromitsu Kudo, Teruhisa Nakai, Seong-Jin Kim
  • Publication number: 20110012154
    Abstract: Provided is a GaN-based LED element having a novel structure for improving output by increasing light extraction efficiency.
    Type: Application
    Filed: November 7, 2008
    Publication date: January 20, 2011
    Applicant: Mitsubishi Chemical Corporation
    Inventors: Hiroaki Okagawa, Shin Hiraoka, Takahide Jouichi, Toshihiko Shima
  • Publication number: 20100314642
    Abstract: A nitride semiconductor light-emitting diode element 1 includes a nitride semiconductor layer 12 having a bottom surface and an upper surface and containing a light emitting layer 12b inside, and a supporting substrate 11 made from a metal is bonded to the bottom surface of the nitride semiconductor layer 12. A light reflecting depression A1 to reflect light generated in the light emitting layer 12b is formed in the bottom surface of the nitride semiconductor layer 12. According to the nitride semiconductor light-emitting diode element 1, since the light generated from the light emitting layer 12b and propagated in the nitride semiconductor layer 12 in a layer direction is reflected by the light reflecting depression A1 and its travel direction is changed, the ratio of the light incident upon the upper surface of the nitride semiconductor layer 12 within a critical angle is increased.
    Type: Application
    Filed: October 19, 2007
    Publication date: December 16, 2010
    Applicant: MITSUBISHI CHEMICAL CORPORATION
    Inventors: Hiromitsu Kudo, Hirokazu Taniguchi, Hiroaki Okagawa, Shin Hiraoka, Takahide Joichi, Toshihiko Shima
  • Publication number: 20100019247
    Abstract: A light emitting device is constituted by flip-chip mounting a GaN-based LED chip 100 of the following (a): (a) the a GaN-based LED chip 100 comprising a light-transmissive substrate 101 and GaN-based semiconductor layer L formed on the light-transmissive substrate 101, wherein the GaN-based semiconductor layer L has a laminate structure containing n-type layer 102, light emitting layer 103 and p-type layer 104 in this order from the light-transmissive substrate 101 side, wherein a positive electrode E101 is formed on the p-type layer 104, said electrode E101 containing a light-transmissive electrode E101a of an oxide semiconductor and a positive contact electrode E101b electrically connected to the light-transmissive electrode, and the area of the positive contact electrode E101b is less than ½ of the area of the upper surface of the p-type layer 104.
    Type: Application
    Filed: October 5, 2007
    Publication date: January 28, 2010
    Inventors: Takahide Joichi, Hiroaki Okagawa, Shin Hiraoka, Toshihiko Shima, Hirokazu Taniguchi
  • Publication number: 20100012971
    Abstract: A first conductive film 104-1 and a positive pad electrode 105 are electrically connected through a second conductive film 104-2 in a GaN-based LED element 100. The contact resistance of a conductive oxide film 104 with a p-type layer 102-3 in a first contact portion 104A is made lower than in a second contact portion 104B, so that a current supplied from the positive pad electrode 105 to the p-type layer 102-3 through the conductive oxide film 104 flows to the p-type layer 102-3 mainly through the first contact portion 104A.
    Type: Application
    Filed: February 20, 2008
    Publication date: January 21, 2010
    Inventors: Shin Hiraoka, Hiroaki Okagawa, Takahide Joichi
  • Patent number: 7589001
    Abstract: A growth plane of substrate 1 is processed to have a concavo-convex surface. The bottom of the concave part may be masked. When a crystal is grown by vapor phase growth using this substrate, an ingredient gas does not sufficiently reach the inside of a concave part 12, and therefore, a crystal growth occurs only from an upper part of a convex part 11. As shown in FIG. 1(b), therefore, a crystal unit 20 occurs when the crystal growth is started, and as the crystal growth proceeds, films grown in the lateral direction from the upper part of the convex part 11 as a starting point are connected to cover the concavo-convex surface of the substrate 1, leaving a cavity 13 in the concave part, as shown in FIG. 1(c), thereby giving a crystal layer 2, whereby the semiconductor base of the present invention is obtained. In this case, the part grown in the lateral direction, or the upper part of the concave part 12 has a low dislocation region and the crystal layer prepared has high quality.
    Type: Grant
    Filed: September 29, 2006
    Date of Patent: September 15, 2009
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Kazuyuki Tadatomo, Hiroaki Okagawa, Yoichiro Ouchi, Masahiro Koto
  • Patent number: 7504324
    Abstract: A growth plane of substrate 1 is processed to have a concavo-convex surface. The bottom of the concave part may be masked. When a crystal is grown by vapor phase growth using this substrate, an ingredient gas does not sufficiently reach the inside of a concave part 12, and therefore, a crystal growth occurs only from an upper part of a convex part 11. As shown in FIG. 1(b), therefore, a crystal unit 20 occurs when the crystal growth is started, and as the crystal growth proceeds, films grown in the lateral direction from the upper part of the convex part 11 as a starting point are connected to cover the concavo-convex surface of the substrate 1, leaving a cavity 13 in the concave part, as shown in FIG. 1(c), thereby giving a crystal layer 2, whereby the semiconductor base of the present invention is obtained. In this case, the part grown in the lateral direction, or the upper part of the concave part 12 has a low dislocation region and the crystal layer prepared has high quality.
    Type: Grant
    Filed: September 29, 2006
    Date of Patent: March 17, 2009
    Assignee: Mitsubishi Chemical Corporation
    Inventors: Kazuyuki Tadatomo, Hiroaki Okagawa, Yoichiro Ouchi, Masahiro Koto