Patents by Inventor Takayuki Yuasa

Takayuki Yuasa 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: 7462882
    Abstract: A nitride semiconductor laser device has a nitride semiconductor substrate that includes a dislocation-concentrated region 102 and a wide low-dislocation region and that has the top surface thereof slanted at an angle in the range of 0.3° to 0.7° relative to the C plane and a nitride semiconductor layer laid on top thereof. The nitride semiconductor layer has a depression immediately above the dislocation-concentrated region, and has, in a region thereof other than the depression, a high-quality quantum well active layer with good flatness and without cracks, a layer that, as is grown, readily exhibits p-type conductivity, and a stripe-shaped laser light waveguide region. The laser light waveguide region is formed above the low-dislocation region. This helps realize a nitride semiconductor laser device that offers a longer life.
    Type: Grant
    Filed: April 26, 2004
    Date of Patent: December 9, 2008
    Assignees: Sharp Kabushiki Kaisha, Sumitomo Electric Industries, Ltd.
    Inventors: Yoshihiro Ueta, Teruyoshi Takakura, Takeshi Kamikawa, Yuhzoh Tsuda, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
  • Publication number: 20080087905
    Abstract: A nitride compound semiconductor light emitting device includes: a GaN substrate having a crystal orientation which is tilted away from a <0001> direction by an angle which is equal to or greater than about 0.05° and which is equal to or less than about 2°, and a semiconductor multilayer structure formed on the GaN substrate, wherein the semiconductor multilayer structure includes: an acceptor doping layer containing a nitride compound semiconductor; and an active layer including a light emitting region.
    Type: Application
    Filed: November 16, 2007
    Publication date: April 17, 2008
    Applicant: SHARP KABUSHIKI KAISHA
    Inventors: Yoshihiro UETA, Takayuki YUASA, Atsushi OGAMA, Yuhzoh TSUDA, Masahiro ARAKI
  • Patent number: 7352012
    Abstract: A nitride compound semiconductor light emitting device includes: a GaN substrate having a crystal orientation which is tilted away from a <0001> direction by an angle which is equal to or greater than about 0.05° and which is equal to or less than about 2°, and a semiconductor multilayer structure formed on the GaN substrate, wherein the semiconductor multilayer structure includes: an acceptor doping layer containing a nitride compound semiconductor; and an active layer including a light emitting region.
    Type: Grant
    Filed: April 20, 2006
    Date of Patent: April 1, 2008
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yoshihiro Ueta, Takayuki Yuasa, Atsushi Ogawa, Yuhzoh Tsuda, Masahiro Araki
  • Publication number: 20070194693
    Abstract: Disclosed is a light-emitting device comprising a semiconductor excitation light source emitting blue-violet light and a solid material illuminant having an absorbent for the blue-violet light containing samarium (Sm). With such a constitution, the light-emitting device has high efficiency, long life and excellent color rendering properties.
    Type: Application
    Filed: March 22, 2005
    Publication date: August 23, 2007
    Inventors: Hajime Saito, Mototaka Taneya, Takayuki Yuasa, Tatsuya Ryowa, Setsuhisa Tanabe, Yoichiu Kawakami, Shizuo Fujita, Mitsuru Funato
  • Publication number: 20060202188
    Abstract: A nitride semiconductor laser device has a nitride semiconductor substrate that includes a dislocation-concentrated region 102 and a wide low-dislocation region and that has the top surface thereof slanted at an angle in the range of 0.3° to 0.7° relative to the C plane and a nitride semiconductor layer laid on top thereof. The nitride semiconductor layer has a depression immediately above the dislocation-concentrated region, and has, in a region thereof other than the depression, a high-quality quantum well active layer with good flatness and without cracks, a layer that, as is grown, readily exhibits p-type conductivity, and a stripe-shaped laser light waveguide region. The laser light waveguide region is formed above the low-dislocation region. This helps realize a nitride semiconductor laser device that offers a longer life.
    Type: Application
    Filed: May 18, 2006
    Publication date: September 14, 2006
    Applicants: SHARP KABUSHIKI KAISHA, SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Yoshihiro Ueta, Teruyoshi Takakura, Takeshi Kamikawa, Yuhzoh Tsuda, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
  • Publication number: 20060189012
    Abstract: A nitride compound semiconductor light emitting device includes: a GaN substrate having a crystal orientation which is tilted away from a <0001> direction by an angle which is equal to or greater than about 0.05° and which is equal to or less than about 2°, and a semiconductor multilayer structure formed on the GaN substrate, wherein the semiconductor multilayer structure includes an acceptor doping layer containing a nitride compound semiconductor; and an active layer including a light emitting region.
    Type: Application
    Filed: April 20, 2006
    Publication date: August 24, 2006
    Applicant: SHARP KABUSHIKI KAISHA
    Inventors: Yoshihiro Ueta, Takayuki Yuasa, Atsushi Ogawa, Yuhzoh Tsuda, Masahiro Araki
  • Patent number: 7064357
    Abstract: A nitride compound semiconductor light emitting device includes: a GaN substrate having a crystal orientation which is tilted away from a <0001> direction by an angle which is equal to or greater than about 0.05° and which is equal to or less than about 2°, and a semiconductor multilayer structure formed on the GaN substrate, wherein the semiconductor multilayer structure includes: an acceptor doping layer containing a nitride compound semiconductor; and an active layer including a light emitting region.
    Type: Grant
    Filed: January 12, 2001
    Date of Patent: June 20, 2006
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yoshihiro Ueta, Takayuki Yuasa, Atsushi Ogawa, Yuhzoh Tsuda, Masahiro Araki
  • Publication number: 20060065197
    Abstract: A vapor deposition apparatus of the present invention has a substrate holder having a substrate holding surface for holding a substrate thereon, and a flow channel for supplying a source gas onto the substrate. The flow channel has an upper wall and a lower wall. An aperture portion is provided in the lower wall of the flow channel. The substrate holding surface of the substrate holder fits in the aperture portion while forming a space between the substrate holding surface and the aperture portion. A means for reducing leakage of gas through the space between the aperture portion and the substrate holder is provided. With this structure, since a means for reducing leakage of gas through the space between the aperture portion and the substrate holder is provided, the conductance with respect to outflow of gas increases, which in turn reduces variations in the amount of outflow gas. This results in high yield production of nitride semiconductor devices with a long life and high light-emission efficiency.
    Type: Application
    Filed: September 27, 2005
    Publication date: March 30, 2006
    Inventors: Eiji Yamada, Takayuki Yuasa, Masahiro Araki, Nakao Akutsu
  • Patent number: 7015058
    Abstract: A nitride semiconductor laser device using a group III nitride semiconductor also as a substrate offers excellent operation characteristics and a long laser oscillation life. In a layered structure of a group III nitride semiconductor formed on a GaN substrate, a laser optical waveguide region is formed elsewhere than right above a dislocation-concentrated region extending so as to vertically penetrate the substrate, and electrodes are formed on the top surface of the layered structure and on the bottom surface of the substrate elsewhere than right above or below the dislocation-concentrated region. In a portion of the top surface of the layered structure and in a portion of the bottom surface of the substrate right above and below the dislocation-concentrated region, dielectric layers may be formed to prevent the electrodes from making contact with those regions.
    Type: Grant
    Filed: August 13, 2004
    Date of Patent: March 21, 2006
    Assignees: Sharp Kabushiki Kaisha, Sumitomo Electric Industries, Ltd.
    Inventors: Kunihiro Takatani, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
  • Publication number: 20060057824
    Abstract: The present invention relates to an apparatus for producing a nitride semiconductor by crystal-growing the nitride semiconductor on a substrate by diffusing a gas containing a source gas of group III element and a source gas of group V element. The gas is diffused in parallel with the substrate and from upstream to downstream. The apparatus has the substrate housed in the apparatus and a flow channel for allowing the gas to flow in the flow channel. The apparatus also has a plurality of protrusions provided on an inner wall of the flow channel. A partition for causing the source gas of group III element and the source gas of group V element to be introduced separately into the flow channel is provided on the upstream portion of the flow channel and in a horizontal direction. The protrusions are formed on the upper and lower surfaces of the partition. With this structure, the source gas of group III element and the source gas of group V element are more uniformly mixed before the source gases are supplied.
    Type: Application
    Filed: September 9, 2005
    Publication date: March 16, 2006
    Inventors: Masahiro Araki, Eiji Yamada, Takayuki Yuasa, Yuhzoh Tsuda, Nakao Akutsu
  • Patent number: 6984841
    Abstract: The nitride semiconductor light emitting device includes a nitride semiconductor underlayer (102) grown on a surface of a nitride semiconductor substrate or a surface of a nitride semiconductor substrate layer laminated over a base substrate of other than a nitride semiconductor, and a light emitting device structure having a light emitting layer (106) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer (103–105) and a p type layer (107–110) over the nitride semiconductor underlayer. It includes a depression (D) not flattened on a surface of the light emitting device structure even after growth of the light emitting device structure.
    Type: Grant
    Filed: January 30, 2002
    Date of Patent: January 10, 2006
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yuhzoh Tsuda, Daisuke Hanaoka, Takayuki Yuasa, Shigetoshi Ito, Mototaka Taneya
  • Patent number: 6924512
    Abstract: A nitride semiconductor light emitting device includes an emission layer (106) having a multiple quantum well structure where a plurality of quantum well layers and a plurality of barrier layers are alternately stacked. The quantum well layer is formed of XN1-x-y-zAsxPySbz (0?x?0.15, 0?y?0.2, 0?z?0.05, x+y+z>0) where X represents one or more kinds of group III elements. The barrier layer is formed of a nitride semiconductor layer containing at least Al.
    Type: Grant
    Filed: May 7, 2001
    Date of Patent: August 2, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yuhzoh Tsuda, Takayuki Yuasa, Shigetoshi Ito
  • Publication number: 20050141577
    Abstract: A nitride semiconductor laser device has a nitride semiconductor substrate that includes a dislocation-concentrated region 102 and a wide low-dislocation region and that has the top surface thereof slanted at an angle in the range of 0.3° to 0.7° relative to the C plane and a nitride semiconductor layer laid on top thereof. The nitride semiconductor layer has a depression immediately above the dislocation-concentrated region, and has, in a region thereof other than the depression, a high-quality quantum well active layer with good flatness and without cracks, a layer that, as is grown, readily exhibits p-type conductivity, and a stripe-shaped laser light waveguide region. The laser light waveguide region is formed above the low-dislocation region. This helps realize a nitride semiconductor laser device that offers a longer life.
    Type: Application
    Filed: April 26, 2004
    Publication date: June 30, 2005
    Applicants: Sharp Kabushiki Kaisha, Sumitomo Electric Industries, Ltd.
    Inventors: Yoshihiro Ueta, Teruyoshi Takakura, Takeshi Kamikawa, Yuhzoh Tsuda, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
  • Patent number: 6891201
    Abstract: A nitride semiconductor light emitting device includes a processed substrate (101a) including a groove and a hill formed on a main surface of a nitride semiconductor substrate, a nitride semiconductor underlayer (102) covering the groove and the hill of the processed substrate, and a light emitting device structure having a light emitting layer (106) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer (103-105) and a p type layer (107-110) over the nitride semiconductor underlayer. A current-constricting portion of the light emitting device structure is formed above a region more than 1 ?m away from the center of the groove in the width direction and more than 1 ?m away from the center of the hill in the width direction.
    Type: Grant
    Filed: January 9, 2002
    Date of Patent: May 10, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yuhzoh Tsuda, Takayuki Yuasa, Shigetoshi Ito, Mototaka Taneya, Yukio Yamasaki
  • Publication number: 20050048682
    Abstract: A nitride semiconductor laser device using a group III nitride semiconductor also as a substrate offers excellent operation characteristics and a long laser oscillation life. In a layered structure of a group III nitride semiconductor formed on a GaN substrate, a laser optical waveguide region is formed elsewhere than right above a dislocation-concentrated region extending so as to vertically penetrate the substrate, and electrodes are formed on the top surface of the layered structure and on the bottom surface of the substrate elsewhere than right above or below the dislocation-concentrated region. In a portion of the top surface of the layered structure and in a portion of the bottom surface of the substrate right above and below the dislocation-concentrated region, dielectric layers may be formed to prevent the electrodes from making contact with those regions.
    Type: Application
    Filed: August 13, 2004
    Publication date: March 3, 2005
    Applicants: SHARP KABUSHIKI KAISHA, SUMITOMO ELECTRIC INDUSTRIES, LTD.
    Inventors: Kunihiro Takatani, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
  • Publication number: 20050042787
    Abstract: A nitride semiconductor laser device with a reduction in internal crystal defects and an alleviation in stress, and a semiconductor optical apparatus comprising this nitride semiconductor laser device. First, a growth suppressing film against GaN crystal growth is formed on the surface of an n-type GaN substrate equipped with alternate stripes of dislocation concentrated regions showing a high density of crystal defects and low-dislocation regions so as to coat the dislocation concentrate regions. Next, the n-type GaN substrate coated with the growth suppressing film is overlaid with a nitride semiconductor layer by the epitaxial growth of GaN crystals. Further, the growth suppressing film is removed to adjust the lateral distance between a laser waveguide region and the closest dislocation concentrated region to 40 ?m or more.
    Type: Application
    Filed: October 28, 2002
    Publication date: February 24, 2005
    Inventors: Shigetoshi Ito, Takayuki Yuasa, Yoshihiro Ueta, Mototaka Taneya, Zenpei Tani, Kensaku Motoki
  • Patent number: 6812496
    Abstract: A nitride semiconductor laser device using a group III nitride semiconductor also as a substrate offers excellent operation characteristics and a long laser oscillation life. In a layered structure of a group III nitride semiconductor formed on a GaN substrate, a laser optical waveguide region is formed elsewhere than right above a dislocation-concentrated region extending so as to vertically penetrate the substrate, and electrodes are formed on the top surface of the layered structure and on the bottom surface of the substrate elsewhere than right above or below the dislocation-concentrated region. In a portion of the top surface of the layered structure and in a portion of the bottom surface of the substrate right above and below the dislocation-concentrated region, dielectric layers may be formed to prevent the electrodes from making contact with those regions.
    Type: Grant
    Filed: December 31, 2002
    Date of Patent: November 2, 2004
    Assignees: Sharp Kabushiki Kaisha, Sumitomo Electric Industries, Ltd.
    Inventors: Kunihiro Takatani, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
  • Publication number: 20040113141
    Abstract: A nitride semiconductor light emitting device includes a processed substrate (101a) including a groove and a hill formed on a main surface of a nitride semiconductor substrate, a nitride semiconductor underlayer (102) covering the groove and the hill of the processed substrate, and a light emitting device structure having a light emitting layer (106) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer (103-105) and a p type layer (107-110) over the nitride semiconductor underlayer. A current-constricting portion of the light emitting device structure is formed above a region more than 1 &mgr;m away from the center of the groove in the width direction and more than 1 &mgr;m away from the center of the hill in the width direction.
    Type: Application
    Filed: July 14, 2003
    Publication date: June 17, 2004
    Inventors: Yuhzoh Isuda, Takayuki Yuasa, Shigetoshi Ito, Mototaka Taneya, Yukio Yamasaki
  • Publication number: 20040041156
    Abstract: The nitride semiconductor light emitting device includes a nitride semiconductor underlayer (102) grown on a surface of a nitride semiconductor substrate or a surface of a nitride semiconductor substrate layer laminated over a base substrate of other than a nitride semiconductor, and a light emitting device structure having a light emitting layer (106) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer (103-105) and a p type layer (107-110) over the nitride semiconductor underlayer. It includes a depression (D) not flattened on a surface of the light emitting device structure even after growth of the light emitting device structure.
    Type: Application
    Filed: August 14, 2003
    Publication date: March 4, 2004
    Inventors: Yuhzoh Tsuda, Daisuke Hanaoka, Takayuki Yuasa, Shigetoshi Ito, Motokata Taneya
  • Patent number: 6685773
    Abstract: A crystal growth method for growing a nitride semiconductor crystal on a sapphire substrate in a vapor phase, includes the steps of: providing a sapphire substrate having a substrate orientation inclined by about 0.05° to about 0.2° from a <0001>orientation; and allowing a nitride semiconductor crystal to grow on the surface of the sapphire substrate.
    Type: Grant
    Filed: May 3, 2001
    Date of Patent: February 3, 2004
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yoshihiro Ueta, Takayuki Yuasa