Patents by Inventor Takao Nakamura

Takao Nakamura 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: 20120114002
    Abstract: Provided is a Group III nitride semiconductor laser diode with a cladding layer capable of providing high optical confinement and carrier confinement. An n-type Al0.08Ga0.92N cladding layer is grown so as to be lattice-relaxed on a (20-21)-plane GaN substrate. A GaN optical guiding layer is grown so as to be lattice-relaxed on the n-type cladding layer. An active layer, a GaN optical guiding layer, an Al0.12Ga0.88N electron blocking layer, and a GaN optical guiding layer are grown so as not to be lattice-relaxed on the optical guiding layer. A p-type Al0.08Ga0.92N cladding layer is grown so as to be lattice-relaxed on the optical guiding layer. A p-type GaN contact layer is grown so as not to be lattice-relaxed on the p-type cladding layer, to produce a semiconductor laser. Dislocation densities at junctions are larger than those at the other junctions.
    Type: Application
    Filed: November 11, 2011
    Publication date: May 10, 2012
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yohei ENYA, Yusuke YOSHIZUMI, Takashi KYONO, Katsushi AKITA, Masaki UENO, Takamichi SUMITOMO, Takao NAKAMURA
  • Publication number: 20120114168
    Abstract: A digital watermark embedding apparatus for embedding embedding information into an input signal having dimensions equal to or greater than N(N is an integer equal to or greater than 2). The apparatus generates an embedding sequence based on the embedding information, generates an N?1-dimensional pattern based on the embedding sequence, generates an N-dimensional embedding pattern by modulating a periodic signal according to a value on the N?1-dimensional pattern, and superimposes the embedding pattern in the input signal and outputs it. A digital watermark detection apparatus measures a component of a predetermined periodic signal in a direction of a dimension of the input signal to obtain an N?1-dimensional pattern, obtains a detection sequence from values of the N?1 dimensional pattern, and detects the embedded digital watermark based on a size of correlation value between the detection sequence and an embedding sequence.
    Type: Application
    Filed: November 22, 2011
    Publication date: May 10, 2012
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORP.
    Inventors: Susumu YAMAMOTO, Takao NAKAMURA
  • Publication number: 20120088326
    Abstract: A method of fabricating a group-III nitride semiconductor laser device includes: preparing a substrate of a hexagonal group-III nitride semiconductor, where the substrate has a semipolar primary surface; forming a substrate product having a laser structure, an anode electrode and a cathode electrode, where the laser structure includes the substrate and a semiconductor region, and where the semiconductor region is formed on the semipolar primary surface; scribing a first surface of the substrate product in part in a direction of the a-axis of the hexagonal group-III nitride semiconductor; and carrying out breakup of the substrate product by press against a second surface of the substrate product, to form another substrate product and a laser bar.
    Type: Application
    Filed: October 20, 2011
    Publication date: April 12, 2012
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yusuke YOSHIZUMI, Yohei ENYA, Takashi KYONO, Masahiro ADACHI, Katsushi AKITA, Masaki UENO, Takamichi SUMITOMO, Shinji TOKUYAMA, Koji KATAYAMA, Takao NAKAMURA, Takatoshi IKEGAMI
  • Publication number: 20120086015
    Abstract: A group III nitride semiconductor device having a gallium nitride based semiconductor film with an excellent surface morphology is provided. A group III nitride optical semiconductor device includes a group III nitride semiconductor supporting base, a GaN based semiconductor region, an active layer, and a GaN semiconductor region. The primary surface of the group III nitride semiconductor supporting base is not any polar plane, and forms a finite angle with a reference plane that is orthogonal to a reference axis extending in the direction of a c-axis of the group III nitride semiconductor. The GaN based semiconductor region, grown on the semipolar primary surface, includes a semiconductor layer of, for example, an n-type GaN based semiconductor doped with silicon. A GaN based semiconductor layer of an oxygen concentration of 5×1016 cm?3 or more provides an active layer, grown on the primary surface, with an excellent crystal quality.
    Type: Application
    Filed: September 23, 2011
    Publication date: April 12, 2012
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Takashi KYONO, Yusuke YOSHIZUMI, Yohei ENYA, Katsushi AKITA, Masaki UENO, Takamichi SUMITOMO, Takao NAKAMURA
  • Publication number: 20120080659
    Abstract: In the nitride based semiconductor optical device, the strained well layers extend along a reference plane tilting at a tilt angle ? from the plane that is orthogonal to a reference axis extending in the direction of the c-axis. A gallium nitride based semiconductor layer is adjacent to a light-emitting layer with a negative piezoelectric field and has a band gap larger than that of a barrier layer. The direction of the piezoelectric field in the well layer is directed in a direction from the n-type layer to the p-type layer, and the piezoelectric field in the gallium nitride based semiconductor layer is directed in a direction from the p-type layer to the n-type layer. Consequently, the valence band, not the conduction band, has a dip at the interface between the light-emitting layer and the gallium nitride based semiconductor layer.
    Type: Application
    Filed: October 21, 2011
    Publication date: April 5, 2012
    Applicant: Sumitomo Electric Industries, Ltd.
    Inventors: Masaki UENO, Yohei Enya, Takashi Kyono, Katsushi Akita, Yusuke Yoshizumi, Takamichi Sumitomo, Takao Nakamura
  • Publication number: 20120070032
    Abstract: A digital watermark embedding apparatus for embedding embedding information, as digital watermark, into an input signal having dimensions equal to or greater than N (N is an integer equal to or greater than 2) and a digital watermark detection apparatus for detecting the digital watermark are disclosed. The digital watermark embedding apparatus generates an embedding sequence based on embedding information, generates a N?1-dimensional pattern based on the embedding sequence, generates N-dimensional embedding pattern by modulating a periodic signal according to a value on the N?1-dimensional pattern, and superimposing the embedding pattern in the input signal and outputs it.
    Type: Application
    Filed: November 22, 2011
    Publication date: March 22, 2012
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORP.
    Inventors: Susumu YAMAMOTO, Takao Nakamura
  • Publication number: 20120061643
    Abstract: A GaN-based semiconductor light emitting device 11a includes a substrate 13 composed of a GaN-based semiconductor having a primary surface 13a tilting from the c-plane toward the m-axis at a tilt angle ? of more than or equal to 63 degrees and less than 80 degrees, a GaN-based semiconductor epitaxial region 15, an active layer 17, an electron blocking layer 27, and a contact layer 29. The active layer 17 is composed of a GaN-based semiconductor containing indium. The substrate 13 has a dislocation density of 1×107 cm?2 or less. In the GaN-based semiconductor light emitting device 11a provided with the active layer containing indium, a decrease in quantum efficiency under high current injection can be moderated.
    Type: Application
    Filed: November 14, 2011
    Publication date: March 15, 2012
    Applicant: Sumitomo Electric Industries, Ltd.
    Inventors: Yohei Enya, Takashi Kyono, Takamichi Sumitomo, Katsushi Akita, Masaki Ueno, Takao Nakamura
  • Publication number: 20120058583
    Abstract: Provided is a group-III nitride semiconductor laser device with a laser cavity allowing for a low threshold current, on a semipolar surface of a support base in which the c-axis of a hexagonal group-III nitride is tilted toward the m-axis. First and second fractured faces 27, 29 to form the laser cavity intersect with an m-n plane. The group-III nitride semiconductor laser device 11 has a laser waveguide extending in a direction of an intersecting line between the m-n plane and the semipolar surface 17a. In a laser structure 13, a first surface 13a is opposite to a second surface 13b. The first and second fractured faces 27, 29 extend from an edge 13c of the first surface to an edge 13d of the second surface 13b. The fractured faces are not formed by dry etching and are different from conventionally-employed cleaved facets such as c-planes, m-planes, or a-planes.
    Type: Application
    Filed: September 22, 2011
    Publication date: March 8, 2012
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yusuke Yoshizumi, Yohei Enya, Takashi Kyono, Masahiro Adachi, Katsushi Akita, Masaki Ueno, Takamichi Sumitomo, Shinji Tokuyama, Koji Katayama, Takao Nakamura, Takatoshi Ikegami
  • Patent number: 8126202
    Abstract: A digital watermark embedding method of the present invention includes: a step of sequentially obtaining each frame image of the moving image data and frame display time; a step of generating a watermark pattern using watermark information, the frame display time and watermark pattern switching information; a step of superimposing the watermark pattern onto the frame image, and combining watermark embedded frame images obtained by sequentially repeating the processes to generate watermark embedded moving image data. A digital watermark detection method includes a step of sequentially obtaining a frame image; a step of generating a difference image between the currently obtained frame image and a previously obtained frame image; and a step of performing digital watermark detection from the difference image to output digital watermark detection status, and when digital watermark detection process is continued, obtaining a new frame again to repeat the above processes.
    Type: Grant
    Filed: May 11, 2011
    Date of Patent: February 28, 2012
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Takao Nakamura, Susumu Yamamoto, Ryo Kitahara, Takashi Miyatake, Atushi Katayama, Hisato Miyachi
  • Patent number: 8076455
    Abstract: The present inventors conducted a similarity search of the amino acid sequence of known G protein-coupled receptor proteins in GenBank, and obtained a novel human GPCR gene “BG37”, cDNA containing the ORF of the gene was cloned and its nucleotide sequence was determined. Moreover, novel GPCR “BG37” genes from mouse and rat were isolated. Use of the novel GPCR of the present invention enables screening of ligands, compounds inhibiting the binding to a ligand, and candidate compounds of pharmaceuticals which can regulate signal transduction from the “BG37” receptor.
    Type: Grant
    Filed: March 3, 2010
    Date of Patent: December 13, 2011
    Assignee: Merck Sharp & Dohme Corp.
    Inventors: Takaharu Maruyama, Takao Nakamura, Hiraku Itadani, Ken-ichi Tanaka
  • Patent number: 8067257
    Abstract: In the nitride based semiconductor optical device LE1, the strained well layers 21 extend along a reference plane SR1 tilting at a tilt angle ? from the plane that is orthogonal to a reference axis extending in the direction of the c-axis. The tilt angle ? is in the range of greater than 59 degrees to less than 80 degrees or greater than 150 degrees to less than 180 degrees. A gallium nitride based semiconductor layer P is adjacent to a light-emitting layer SP? with a negative piezoelectric field and has a band gap larger than that of a barrier layer. The direction of the piezoelectric field in the well layer W3 is directed in a direction from the n-type layer to the p-type layer, and the piezoelectric field in the gallium nitride based semiconductor layer P is directed in a direction from the p-type layer to the n-type layer. Consequently, the valence band, not the conduction band, has a dip at the interface between the light-emitting layer SP? and the gallium nitride based semiconductor layer P.
    Type: Grant
    Filed: November 16, 2010
    Date of Patent: November 29, 2011
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Masaki Ueno, Yohei Enya, Takashi Kyono, Katsushi Akita, Yusuke Yoshizumi, Takamichi Sumitomo, Takao Nakamura
  • Publication number: 20110272734
    Abstract: The present invention is a minimal-defect light-emitting device substrate that enables emitted light to issue from a device's substrate side, and is a light-emitting device 100 substrate furnished with a transparent substrate 10 that is transparent to light of wavelengths between 400 nm and 600 nm, inclusive, and a nitride-based compound semiconductor thin film 1c formed onto one of the major surfaces of the transparent substrate 10 by a join. Letting the thermal expansion coefficient of the transparent substrate along a direction perpendicular to the major surface of the transparent substrate be ?1, and the thermal expansion coefficient of the nitride-based compound semiconductor thin film be ?2, then (?1??2)/?2 is between ?0.5 and 1.0, inclusive, and at up to 1200° C. the transparent substrate does not react with the nitride-based compound semiconductor thin film 1c.
    Type: Application
    Filed: November 11, 2009
    Publication date: November 10, 2011
    Applicant: Sumitomo Electric Industries, Ltd.
    Inventors: Akihiro Hachigo, Takao Nakamura, Masashi Yoshimura
  • Patent number: 8053806
    Abstract: A group III nitride semiconductor device having a gallium nitride based semiconductor film with an excellent surface morphology is provided. A group III nitride optical semiconductor device 11a includes a group III nitride semiconductor supporting base 13, a GaN based semiconductor region 15, an active layer active layer 17, and a GaN semiconductor region 19. The primary surface 13a of the group III nitride semiconductor supporting base 13 is not any polar plane, and forms a finite angle with a reference plane Sc that is orthogonal to a reference axis Cx extending in the direction of a c-axis of the group III nitride semiconductor. The GaN based semiconductor region 15 is grown on the semipolar primary surface 13a. A GaN based semiconductor layer 21 of the GaN based semiconductor region 15 is, for example, an n-type GaN based semiconductor, and the n-type GaN based semiconductor is doped with silicon.
    Type: Grant
    Filed: November 5, 2010
    Date of Patent: November 8, 2011
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Takashi Kyono, Yusuke Yoshizumi, Yohei Enya, Katsushi Akita, Masaki Ueno, Takamichi Sumitomo, Takao Nakamura
  • Publication number: 20110228972
    Abstract: A digital watermark embedding method of the present invention includes: a step of sequentially obtaining each frame image of the moving image data and frame display time; a step of generating a watermark pattern using watermark information, the frame display time and watermark pattern switching information; a step of superimposing the watermark pattern onto the frame image, and combining watermark embedded frame images obtained by sequentially repeating the processes to generate watermark embedded moving image data. A digital watermark detection method includes a step of sequentially obtaining a frame image; a step of generating a difference image between the currently obtained frame image and a previously obtained frame image; and a step of performing digital watermark detection from the difference image to output digital watermark detection status, and when digital watermark detection process is continued, obtaining a new frame again to repeat the above processes.
    Type: Application
    Filed: May 11, 2011
    Publication date: September 22, 2011
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Takao NAKAMURA, Susumu Yamamoto, Ryo Kitahara, Takashi Miyatake, Atushi Katayama, Hisato Miyachi
  • Publication number: 20110228804
    Abstract: Provided is a group-III nitride semiconductor laser device with a laser cavity of high lasing yield, on a semipolar surface of a support base in which the c-axis of a hexagonal group-III nitride is tilted toward the m-axis. First and second fractured faces 27, 29 to form the laser cavity intersect with an m-n plane. The group-III nitride semiconductor laser device 11 has a laser waveguide extending in a direction of an intersecting line between the m-n plane and the semipolar surface 17a. For this reason, it is feasible to make use of emission by a band transition enabling the low threshold current. In a laser structure 13, a first surface 13a is opposite to a second surface 13b. The first and second fractured faces 27, 29 extend from an edge 13c of the first surface 13a to an edge 13d of the second surface 13b. The fractured faces are not formed by dry etching and are different from conventionally-employed cleaved facets such as c-planes, m-planes, or a-planes.
    Type: Application
    Filed: July 14, 2010
    Publication date: September 22, 2011
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yusuke YOSHIZUMI, Shimpei TAKAGI, Yohei ENYA, Takashi KYONO, Masahiro ADACHI, Masaki UENO, Takamichi SUMITOMO, Shinji TOKUYAMA, Koji KATAYAMA, Takao NAKAMURA, Takatoshi IKEGAMI
  • Publication number: 20110223701
    Abstract: A group III nitride semiconductor device having a gallium nitride based semiconductor film with an excellent surface morphology is provided. A group III nitride optical semiconductor device 11a includes a group III nitride semiconductor supporting base 13, a GaN based semiconductor region 15, an active layer active layer 17, and a GaN semiconductor region 19. The primary surface 13a of the group III nitride semiconductor supporting base 13 is not any polar plane, and forms a finite angle with a reference plane Sc that is orthogonal to a reference axis Cx extending in the direction of a c-axis of the group III nitride semiconductor. The GaN based semiconductor region 15 is grown on the semipolar primary surface 13a. A GaN based semiconductor layer 21 of the GaN based semiconductor region 15 is, for example, an n-type GaN based semiconductor, and the n-type GaN based semiconductor is doped with silicon.
    Type: Application
    Filed: May 20, 2011
    Publication date: September 15, 2011
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Takashi KYONO, Yusuke YOSHIZUMI, Yohei ENYA, Katsushi AKITA, Masaki UENO, Takamichi SUMITOMO, Takao NAKAMURA
  • Patent number: 8018029
    Abstract: A gallium nitride-based epitaxial wafer for a nitride light-emitting device comprises a gallium nitride substrate having a primary surface, a gallium nitride-based semiconductor film provided on the primary surface, and, an active layer provided on the semiconductor film, the active layer having a quantum well structure. A normal line of the primary surface and a C-axis of the gallium nitride substrate form an off angle with each other. The off angle monotonically increases on the line that extends from one point to another point through a center point of the primary surface. The one point and the other point are on an edge of the primary surface, and indium contents of the well layer defined at n points on the line monotonically decrease in a direction from the one point to the other point. The thickness values of the well layer defined at the n points monotonically increase in the direction.
    Type: Grant
    Filed: September 23, 2009
    Date of Patent: September 13, 2011
    Assignee: Sumitomo Electric Industries, Ltd.
    Inventors: Yusuke Yoshizumi, Masaki Ueno, Takao Nakamura
  • Publication number: 20110201142
    Abstract: To provide a light-emitting device using a nitride semiconductor which can attain high-power light emission by highly efficient light emission, a method of manufacturing the light-emitting device involves forming a first AlGaN layer of a first conductivity type on a side of a first main surface of a nitride semiconductor substrate, forming a light-emitting layer including an InAlGaN quaternary alloy on the first AlGaN layer, forming a second AlGaN layer of a second conductivity type on the light-emitting layer, and removing the nitride semiconductor substrate after forming the second AlGaN layer.
    Type: Application
    Filed: April 25, 2011
    Publication date: August 18, 2011
    Applicants: SUMITOMO ELECTRIC INDUSTRIES, LTD., RIKEN
    Inventors: Hideki HIRAYAMA, Katsushi AKITA, Takao NAKAMURA
  • Publication number: 20110198566
    Abstract: A method for manufacturing a light emitting element is directed to a method for manufacturing a light emitting element of a III-V group compound semiconductor having a quantum well structure including In and N, including the steps of: forming a well layer including In and N; forming a barrier layer having a bandgap wider than a bandgap of the well layer; and supplying a gas including N and interrupting epitaxial growth after the step of forming the well layer and before the step of forming the barrier layer. In the step of interrupting epitaxial growth, the gas having decomposition efficiency higher than decomposition efficiency of decomposition from N2 and NH3 into active nitrogen at 900° C. is supplied. In addition, in the step of interrupting epitaxial growth, the gas different from a gas used as an N source of the well layer is supplied.
    Type: Application
    Filed: January 27, 2010
    Publication date: August 18, 2011
    Applicant: SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yusuke Yoshizumi, Masaki Ueno, Takao Nakamura, Toshio Ueda, Eiryo Takasuka, Yasuhiko Senda
  • Publication number: 20110186860
    Abstract: Disclosed is a nitride-based semiconductor light emitting device with excellent light extraction efficiency. A light emitting device 11 includes a support base 13 and a semiconductor laminate 15. The semiconductor laminate 15 includes an n-type GaN-based semiconductor region 17, an active layer 19, and a p-type GaN-based semiconductor region 21. The n-type GaN-based semiconductor region 17, the active layer 19, and the p-type GaN-based semiconductor region 21 are mounted on a principal surface 13a, and are arranged in the direction of a predetermined axis Ax orthogonal to the principal surface 13a. A rear surface 13b of the support base 13 is inclined with respect to a plane orthogonal to a reference axis extending in the c-axis direction of a hexagonal gallium nitride semiconductor of the support base 13. A vector VC represents the c-axis direction. A surface morphology M of the rear surface 13b has a plurality of protrusions 23 protruding in the direction of a <000-1>-axis.
    Type: Application
    Filed: April 13, 2011
    Publication date: August 4, 2011
    Applicant: Sumitomo Electric Industries, Ltd.
    Inventors: Yohei ENYA, Yusuke YOSHIZUMI, Takashi KYONO, Masaki UENO, Takao NAKAMURA