Patents by Inventor Shigetoshi Ito

Shigetoshi Ito 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: 7012283
    Abstract: According to an aspect of the present invention, a nitride semiconductor light emitting device includes a light emitting layer (106) having a quantum well structure with quantum well layers and barrier layers laminated alternately. The well layer is formed of a nitride semiconductor containing In, and the barrier layer is formed of a nitride semiconductor layer containing As, P or Sb. According to another aspect of the present invention, a nitride semiconductor light emitting device includes a light emitting layer having a quantum well structure with quantum well layers and barrier layers laminated alternately. The well layer is formed of GaN1?x?y?zAsxPySbz (0<x+y+z?0.3), and the barrier layer is formed of a nitride semiconductor containing In.
    Type: Grant
    Filed: September 17, 2001
    Date of Patent: March 14, 2006
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yuhzoh Tsuda, Shigetoshi Ito, Masahiro Araki
  • 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
  • Publication number: 20050226295
    Abstract: A semiconductor laser device having a waveguide constructed in a stack of layers including, on a substrate transparent and having a refractive index ns for laser light, a first clad layer of a refractive index nc1, a second clad layer of a refractive index nc2, a third clad layer of a refractive index nc3, a first conductivity type guide layer of a refractive index ng, an active quantum well layer, a second conductivity type guide layer, a second conductivity type clad layer, and a second conductivity type contact layer deposited in this order, wherein the waveguide has an effective refractive index ne, and a relationship of nc2<(nc1, nc3)<ne<(ns, ng) is satisfied.
    Type: Application
    Filed: March 26, 2003
    Publication date: October 13, 2005
    Applicant: Sharp Kabushiki Kaisha
    Inventors: Mototaka Taneya, Yukio Yamasaki, Shigetoshi Ito
  • Publication number: 20050168564
    Abstract: A driving method and a driving device are provided for an LED element in which light emitting layers different from each other in light emission wavelength peak, put on each other with a barrier layer being interposed, are sandwiched by a pair of p-type and n-type layers, and color of emitted light from which substantially depends only upon driving current value. The method comprises a driving current value calculation step of obtaining a value for designating a current value corresponding to a desired color of emitted light from the LED element; a driving current generation step of generating a driving current having the current value designated by the value obtained in the driving current value calculation step; and a driving current supply step of supplying the LED element with the driving current generated in the driving current generation step.
    Type: Application
    Filed: January 28, 2005
    Publication date: August 4, 2005
    Inventors: Yoshinobu Kawaguchi, Shigetoshi Ito
  • 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: 20050157769
    Abstract: Provided is a semiconductor laser device that is free from or suffers less from deterioration resulting from a surge or that is less likely to suffer from deterioration resulting from a surge. The semiconductor laser device has a conductive stem 101, a submount 102 fixed to the stem 101, a nitride semiconductor laser chip 103 mounted on the submount 102, pins 104 and 105 fixed to the stem 101 but insulated therefrom, a wire connecting the pin 104 to a p-electrode of the nitride semiconductor laser chip 103, a wire connecting the pin 105 to an n-electrode of the nitride semiconductor laser chip 103, and a cap 106 enclosing the nitride semiconductor laser chip 103 and the submount 102 and fixed to the stem 101.
    Type: Application
    Filed: January 21, 2005
    Publication date: July 21, 2005
    Applicant: Sharp Kabushiki Kaisha
    Inventors: Shigetoshi Ito, Daisuke Hanaoka
  • 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: 6909120
    Abstract: According to an aspect of the present invention, a nitride semiconductor light emitting device includes a light emitting layer having a quantum well structure with quantum well layers and barrier layers laminated alternately. The well layer is formed of a nitride semiconductor containing In, and the barrier layer is formed of a nitride semiconductor layer containing As, P or Sb. According to another aspect of the present invention, a nitride semiconductor light emitting device includes a light emitting layer having a quantum well structure with quantum well layers and barrier layers laminated alternately. The well layer is formed of GaN1?x?y?zAsxPySbz (0<x+y+z?0.3), and the barrier layer is formed of a nitride semiconductor containing In.
    Type: Grant
    Filed: November 5, 2001
    Date of Patent: June 21, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yuhzoh Tsuda, Shigetoshi Ito
  • Publication number: 20050117616
    Abstract: A drive current is generated by mixing a pulse signal from a pulse generator (13) and a DC current from a DC current power supply (14) by means of a T circuit (11) and injected into a nitride semiconductor laser (10) having a horizontal light-confinement ridge structure. The horizontal light-confinement coefficient of the nitride semiconductor laser (10) is between 85% and 99%. The time when the current waveform of the drive current is continuously over the threshold current of the nitride semiconductor laser ranges from 5 [nsec] to 1,000 [nsec].
    Type: Application
    Filed: November 25, 2002
    Publication date: June 2, 2005
    Inventors: Yukio Yamasaki, Shigetoshi Ito
  • Patent number: 6897484
    Abstract: The object of the present invention is to lower the oscillation threshold value and to improve the yield by improving the luminous efficiency in the central wavelength of a laser. To achieve the object, the nitride semiconductor light emitting element of the present invention includes a substrate, a lower clad layer formed of a nitride semiconductor containing Al and Ga formed thereon, a lower guide layer formed of a nitride semiconductor mainly containing In and Ga formed thereon, and an active layer including a nitride semiconductor mainly containing In and Ga formed thereon. The lower guide layer has a first layer and a second layer higher in In content than the first layer, successively stacked from the active layer side.
    Type: Grant
    Filed: September 19, 2003
    Date of Patent: May 24, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Tomoki Ohno, Shigetoshi Ito
  • Patent number: 6891189
    Abstract: A nitride semiconductor laser device includes a nitride semiconductor substrate, and a layered portion corresponding to a nitride semiconductor film grown on the nitride semiconductor substrate, the layered portion including an n-type layer and a p-type layer and a light emitting layer posed between the n- and p-type layers, of the n- and p-type layers a layer opposite to the nitride semiconductor substrate with the light emitting layer opposed therebetween serving as an upper layer having a stripe of 1.9 ?m to 3.0 ?n in width, the light emitting layer and the upper layer having an interface distant from a bottom of the stripe by 0 ?m to 0.2 ?m.
    Type: Grant
    Filed: July 9, 2003
    Date of Patent: May 10, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Shigetoshi Ito, Yuhzoh Tsuda
  • 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: 20050095768
    Abstract: According to an aspect of the present invention, a nitride semiconductor light emitting device includes a light emitting layer having a quantum well structure with quantum well layers and barrier layers laminated alternately. The well layer is formed of a nitride semiconductor containing In, and the barrier layer is formed of a nitride semiconductor layer containing As, P or Sb. According to another aspect of the present invention, a nitride semiconductor light emitting device includes a light emitting layer having a quantum well structure with quantum well layers and barrier layers laminated alternately. The well layer is formed of GaN1-x-y-zAsxPySbz (0<x+y+z?0.3), and the barrier layer is formed of a nitride semiconductor containing In.
    Type: Application
    Filed: November 5, 2001
    Publication date: May 5, 2005
    Inventors: Yuhzoh Tsuda, Shigetoshi Ito
  • Patent number: 6888867
    Abstract: A semiconductor laser device includes a substrate and an n-GaN layer composed of a nitride semiconductor formed on the substrate. The substrate includes a trench having as a slope a plane inclined 62 degrees from the main plane of the substrate, or a plane inclined within 3 degrees in an arbitrary direction from the inclined plane. The n-GaN layer is formed on the slope. On the n-GaN layer are formed a lower clad layer, an active layer, and an upper clad layer, each composed of a nitride semiconductor. The active layer has a plane orientation substantially matching the plane orientation of the main plane.
    Type: Grant
    Filed: March 26, 2002
    Date of Patent: May 3, 2005
    Assignees: Sharp Kabushiki Kaisha
    Inventors: Nobuhiko Sawaki, Yoshio Honda, Norifumi Kameshiro, Masahito Yamaguchi, Norikatsu Koide, Shigetoshi Ito, Tomoki Ono, Katsuki Furukawa
  • Patent number: 6881981
    Abstract: In a nitride semiconductor light emitting device chip, a mask pattern on a nitride semiconductor substrate (101) is formed of a growth inhibiting film on which a nitride semiconductor layer is hard to grow. There are a plurality of windows unprovided with the growth inhibiting film. There are at least two different widths as mask widths each between the adjacent windows. The mask pattern includes a mask A group (MAG) and mask B groups (MBG) arranged on respective sides of the mask A group. A mask A width in the mask A group is wider than a mask B width in the mask B group. The nitride semiconductor light emitting device chip further includes a nitride semiconductor underlayer (102) covering the windows and the mask pattern, and a light emitting device structure having a light emitting layer (106) including at least one quantum well layer between an n type layer (103-105) and a p type layer (107-110) over the underlayer.
    Type: Grant
    Filed: December 27, 2001
    Date of Patent: April 19, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yuhzoh Tsuda, Shigetoshi Ito
  • Patent number: 6873635
    Abstract: A nitride semiconductor laser device includes a first-conductivity-type cladding layer formed of a nitride semiconductor material; an active layer formed of a nitride semiconductor material; and a second-conductivity-type cladding layer formed of a nitride semiconductor material. The first-conductivity-type cladding layer has a first main surface and a second main surface, the first main surfaces being closer to the active layer from the second main surface, and includes a first-conductivity-type first cladding layer and a first-conductivity-type second cladding layer having a different composition from that of the first-conductivity-type first cladding layer, which are provided in this order from the first main surface. The first-conductivity-type first cladding layer has a refractive index lower than that of the first-conductivity-type second cladding layer.
    Type: Grant
    Filed: February 14, 2002
    Date of Patent: March 29, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yukio Yamasaki, Shigetoshi Ito
  • Patent number: 6865201
    Abstract: In connection with a nitride semiconductor laser device optimal for example for optical pickup and an optical information reproduction apparatus having superior condensation characteristics, the semiconductor laser device includes a substrate of nitride semiconductor, a lower clad layer of nitride semiconductor stacked thereon, an active layer stacked thereon, an upper clad layer of nitride semiconductor stacked thereon, and a contact layer of AlaInbGa1?a?bN stacked thereon having a lattice constant larger than the substrate of nitride semiconductor, and the device is cleaved and thus divided to have a surface serving as a resonator mirror.
    Type: Grant
    Filed: March 22, 2002
    Date of Patent: March 8, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Shigetoshi Ito, Yukio Yamasaki, Toshiyuki Kawakami
  • 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: 6858882
    Abstract: A nitride semiconductor light-emitting device includes an emission layer (103) formed on a substrate (100), and the emission layer includes a quantum well layer of GaN1-x?y?zAsxPySbz (0<x+y+z?0.3) containing Al.
    Type: Grant
    Filed: September 4, 2001
    Date of Patent: February 22, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yuhzoh Tsuda, Shigetoshi Ito, Kouichi Morishige