Patents by Inventor Tetsurou Murakami

Tetsurou Murakami 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: 7541621
    Abstract: A semiconductor light emitting device includes a first conductivity-type first semiconductor layer; an emission layer; a second conductivity-type second semiconductor layer; and a second conductivity-type transparent substrate transparent to light beams from the emission layer and directly bonded to the second semiconductor layer. The transparent substrate has a parallel surface almost parallel to the emission layer on an opposite side of the emission layer, and an inclined surface adjoining the parallel surface and inclined to the parallel surface. Light beams totally reflected on the parallel surface and light beams totally reflected on a side surface of the transparent substrate come incident to the inclined surface at an angle smaller than the critical angle, and emit out of the semiconductor light emitting device.
    Type: Grant
    Filed: August 22, 2005
    Date of Patent: June 2, 2009
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ooyama, Osamu Yamamoto
  • Patent number: 7495263
    Abstract: On a GaAs substrate (1), are formed a DBR (Distributed Bragg Reflector) (3), and a light-emitting layer (5) made of a plurality of layers of AlyGazIn1-y-zP (0?y?1, 0?z?1) above the DBR (3). A semiconductor layer or a plurality of semiconductor layers (6)-(10) having a number of layers of 1 or more are formed on the light-emitting layer (5), and a grating pattern for scattering light is formed on a surface of the semiconductor layer (9) by photolithography and by etching with a sulfuric acid/hydrogen peroxide based etchant. Thus, a semiconductor device small in radiation angle dependence of light emission wavelength, as well as a manufacturing method therefor, are provided.
    Type: Grant
    Filed: February 7, 2001
    Date of Patent: February 24, 2009
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroyuki Hosoba, Hiroshi Nakatsu, Tetsurou Murakami, Shouichi Ohyama
  • Patent number: 7348195
    Abstract: An n-type AlAs/n-type Al0.5Ga0.5As DBR layer and a p-type (Al0.2Ga0.8)0.5In0.5P/p-type Al0.5In0.5P DBR layer are formed on an n-type GaAs substrate at specified intervals so that a reflection spectrum is centered at 650 nm and the resonance wavelength becomes 650 nm. A quantum well active layer (light-emitting layer) is formed so that the light emission peak wavelength becomes 650 nm in the belly position of the standing wave generated in a resonator constructed of both the DBR layers. A grating pattern is formed on the surface of a p-type Al0.5Ga0.5As light diffusion layer that serves as a light-emitting surface surrounded by a p-type electrode. By thus roughening the light-emitting surface, light emitted from the light-emitting layer is diffused in various directions, reducing the radiation angle dependency of the emission light wavelength.
    Type: Grant
    Filed: July 28, 2004
    Date of Patent: March 25, 2008
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Hiroyuki Hosoba, Tetsurou Murakami
  • Patent number: 7166865
    Abstract: There is provided and manufactured, at a low cost and with high yields, a semiconductor light emitting device which allows extraction of light produced in an emitter layer not only from its top surface but also from its side surfaces and which has high luminance. An AlGaInP-based semiconductor light emitting device having a contact layer 8 made of (AlyGa1?y)zIn1?zP (0?y?1, 0<z<1) disposed between an emitter layer 3 and a transparent substrate 2 which is transparent to emission wavelengths from the emitter layer 3.
    Type: Grant
    Filed: October 5, 2004
    Date of Patent: January 23, 2007
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama, Hiroshi Nakatsu
  • Publication number: 20060043392
    Abstract: A semiconductor light emitting device includes a first conductivity-type first semiconductor layer; an emission layer; a second conductivity-type second semiconductor layer; and a second conductivity-type transparent substrate transparent to light beams from the emission layer and directly bonded to the second semiconductor layer. The transparent substrate has a parallel surface almost parallel to the emission layer on an opposite side of the emission layer, and an inclined surface adjoining the parallel surface and inclined to the parallel surface. Light beams totally reflected on the parallel surface and light beams totally reflected on a side surface of the transparent substrate come incident to the inclined surface at an angle smaller than the critical angle, and emit out of the semiconductor light emitting device.
    Type: Application
    Filed: August 22, 2005
    Publication date: March 2, 2006
    Applicant: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ooyama, Osamu Yamamoto
  • Patent number: 6924502
    Abstract: A semiconductor light emitting device has in sequence on a semiconductor substrate, a multilayer reflection film, a semiconductor layer, and a quantum well active layer. A distance between an upper surface of the multilayer reflection film and a lower surface of the quantum well active layer is 2?/n or less, where ? is a light emission wavelength and n is an average refractive index of the semiconductor layer disposed in between the multilayer reflection film and the quantum well active layer. A phase difference between a reflected ray of light reflected by the multilayer reflection film and an emitted ray of light from the quantum well active layer is a multiple of 2?. The semiconductor light emitting device stably obtains a specified peak wavelength even when there is slight variance in the distance between the upper surface of the multilayer reflection film and the lower surface of the quantum well active layer.
    Type: Grant
    Filed: October 16, 2002
    Date of Patent: August 2, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Hiroyuki Hosoba, Tetsurou Murakami
  • Publication number: 20050093015
    Abstract: There is provided and manufactured, at a low cost and with high yields, a semiconductor light emitting device which allows extraction of light produced in an emitter layer not only from its top surface but also from its side surfaces and which has high luminance. An AlGaInP-based semiconductor light emitting device having a contact layer 8 made of (AlyGa1-y)zIn1-zP (0?y?1, 0<z<1) disposed between an emitter layer 3 and a transparent substrate 2 which is transparent to emission wavelengths from the emitter layer 3.
    Type: Application
    Filed: October 5, 2004
    Publication date: May 5, 2005
    Applicant: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama, Hiroshi Nakatsu
  • Publication number: 20050031007
    Abstract: Is provided a resonant cavity type light emitting diode having excellent humidity durability and a light output unsaturated even several 10 mA., which is suitable for mass production. The semiconductor light emitting element has a resonator formed by one set of multi-layer reflecting films disposed at a constant distance on a GaAs substrate inclined at an angle of not less than 2 degrees in the direction [011] or [0-1-1] from the plane (100) and a light emitting layer disposed at a loop position of a standing wave in the resonator, wherein a multi-layer reflecting film disposed on the GaAs substrate side is composed of plural layers of AlxGa1-xAs (0?x?1) and a multi-layer reflecting film disposed on the opposite side of the GaAs substrate is composed of plural layers of AlyGazIn1-y-zP (0?y?1, 0?z?1), thereby achieving an improved humidity durability and an increased reflection factor by increasing the number of the reflection layers.
    Type: Application
    Filed: September 3, 2004
    Publication date: February 10, 2005
    Applicant: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Hiroyuki Hosoba, Tetsurou Murakami
  • Publication number: 20050001222
    Abstract: An n-type AlAs/n-type Al0.5Ga0.5As DBR layer and a p-type (Al0.2Ga0.8)0.5In0.5P/p-type Al0.5In0.5P DBR layer are formed on an n-type GaAs substrate at specified intervals so that a reflection spectrum is centered at 650 nm and the resonance wavelength becomes 650 nm. A quantum well active layer (light-emitting layer) is formed so that the light emission peak wavelength becomes 650 nm in the belly position of the standing wave generated in a resonator constructed of both the DBR layers. A grating pattern is formed on the surface of a p-type Al0.5Ga0.5As light diffusion layer that serves as a light-emitting surface surrounded by a p-type electrode. By thus roughening the light-emitting surface, light emitted from the light-emitting layer is diffused in various directions, reducing the radiation angle dependency of the emission light wavelength.
    Type: Application
    Filed: July 28, 2004
    Publication date: January 6, 2005
    Applicant: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Hiroyuki Hosoba, Tetsurou Murakami
  • Patent number: 6822266
    Abstract: A semiconductor light-emitting device includes an active layer having a single quantum well structure. The single quantum well structure enables a high-speed response such that the rise and fall time is 2.1 nsec. Further, the single quantum well active layer is doped with Zn at a concentration of 8×1017 cm−3. Thereby, the half-value width of the light-emitting spectrum is 25 nm or more, which is wider than in the case of no doping. Thus, temperature dependence of an optical output is reduced.
    Type: Grant
    Filed: May 24, 2002
    Date of Patent: November 23, 2004
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Tetsurou Murakami, Shouichi Ohyama
  • Patent number: 6815727
    Abstract: A resonant cavity type light emitting diode has a first DBR made of n-type AlAs or Al0.5Ga0.5As, a quantum well active layer, a second DBR made of p-type (Al0.2Ga0.6)0.5In0.5P or Al0.5In0.5P, and an n-type current constriction layer on an n-type GaAs substrate. The first DBR and the second DBR form a resonator. The quantum well active layer is formed in a position of an antinode of a standing wave inside the resonator. Between the second DBR and the current constriction layer, there is provided a p-type GaP etching protection layer that has a value obtained by dividing resistivity by thickness being 1×103 &OHgr; or more. Since a current in a current flow pass formed in the current constriction layer hardly diffuses to the outside of the current flow pass, there is generated few region with low current density that causes deterioration of responsespeed in a quantum well layer. Thus, the light emitting diode has an excellent high-speed response.
    Type: Grant
    Filed: June 24, 2003
    Date of Patent: November 9, 2004
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama, Hiroshi Nakatsu
  • Patent number: 6797986
    Abstract: Is provided a resonant cavity type light emitting diode having excellent humidity durability and a light output unsaturated even several 10 mA., which is suitable for mass production. The semiconductor light emitting element has a resonator formed by one set of multi-layer reflecting films disposed at a constant distance on a GaAs substrate inclined at an angle of not less than 2 degrees in the direction [011] or [0-1-1] from the plane (100) and a light emitting layer disposed at a loop position of a standing wave in the resonator, wherein a multi-layer reflecting film disposed on the GaAs substrate side is composed of plural layers of AlxGa1-xAs (0 ≦x≦1) and a multi-layer reflecting film disposed on the opposite side of the GaAs substrate is composed of plural layers of AlyGazIn1-y-zP (0≦y≦1, 0≦z≦1), thereby achieving an improved humidity durability and an increased reflection factor by increasing the number of the reflection layers.
    Type: Grant
    Filed: June 30, 2000
    Date of Patent: September 28, 2004
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Hiroyuki Hosoba, Tetsurou Murakami
  • Patent number: 6794687
    Abstract: An n-type AlAs/n-type Al0.5Ga0.5As DBR layer and a p-type (Al0.2Ga0.8)0.5In0.5P/p-type Al0.5In0.5P DBR layer are formed on an n-type GaAs substrate at specified intervals so that a reflection spectrum is centered at 650 nm and the resonance wavelength becomes 650 nm. A quantum well active layer (light-emitting layer) is formed so that the light emission peak wavelength becomes 650 nm in the belly position of the standing wave generated in a resonator constructed of both the DBR layers. A grating pattern is formed on the surface of a p-type Al0.5Ga0.5As light diffusion layer that serves as a light-emitting surface surrounded by a p-type electrode. By thus roughening the light-emitting surface, light emitted from the light-emitting layer is diffused in various directions, reducing the radiation angle dependency of the emission light wavelength.
    Type: Grant
    Filed: August 25, 2000
    Date of Patent: September 21, 2004
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Hiroyuki Hosoba, Tetsurou Murakami
  • Publication number: 20040126918
    Abstract: A light emitting layer 4 composed of a single or a plurality of semiconductor layers is laminated on a nondope type, weak p-type, or n-type first semiconductor substrate (not shown in FIG. 1). On the light emitting layer 4, n-type semiconductor layers 5-7 composed of a single layer or a plurality of layers are laminated. On the surface of the n-type semiconductor layer 7, a second semiconductor substrate 8 transparent to the wavelength of emitted light from the light emitting layer 4 is formed. Then, the first semiconductor substrate is removed. On the plane exposed by removal of the first semiconductor substrate, a translucent electrode layer 9 transparent to the wavelength of emitted light from the light emitting layer is formed.
    Type: Application
    Filed: October 14, 2003
    Publication date: July 1, 2004
    Applicant: SHARP KABUSHIKI KAISHA
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Tetsurou Murakami, Shouichi Ooyama
  • Publication number: 20040036075
    Abstract: A resonant cavity type light emitting diode has a first DBR made of n-type AlAs or Al0.5Ga0.5As, a quantum well active layer, a second DBR made of p-type (Al0.2Ga0.8)0.5In0.5P or Al0.5In0.5P, and an n-type current constriction layer on an n-type GaAs substrate. The first DBR and the second DBR form a resonator. The quantum well active layer is formed in a position of an antinode of a standing wave inside the resonator. Between the second DBR and the current constriction layer, there is provided a p-type GaP etching protection layer that has a value obtained by dividing resistivity by thickness being 1×103 &OHgr; or more. Since a current in a current flow pass formed in the current constriction layer hardly diffuses to the outside of the current flow pass, there is generated few region with low current density that causes deterioration of response speed in a quantum well layer. Thus, the light emitting diode has an excellent high-speed response.
    Type: Application
    Filed: June 24, 2003
    Publication date: February 26, 2004
    Applicant: SHARP KABUSHIKI KAISHA
    Inventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama, Hiroshi Nakatsu
  • Patent number: 6617614
    Abstract: The present invention relates to a semiconductor light-emitting device used for optical transmission (particularly for IEEE 1394) and displays and the like. More specifically, an object of the present invention is to provide a semiconductor light-emitting device capable of emitting the light with a high efficiency by extending a distance from an active layer to a boundary having poor crystal quality due to Group V elements As and P exchange to suppress deterioration in crystal quality of the active layer.
    Type: Grant
    Filed: September 4, 2001
    Date of Patent: September 9, 2003
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Tetsurou Murakami, Hiroyuki Hosoba
  • Patent number: 6617606
    Abstract: A light-emitting diode having an excellent high-speed response characteristic and capable of giving a large light output with a small variation of the light output during the operation is provided. In the light-emitting diode, an active layer comprising a single quantum well layer of p-type Ga0.51In0.49P, a lower barrier layer of p-type (Al0.5Ga0.5)0.51In0.49P and an upper barrier layer of p-type (Al0.5Ga0.5)0.51In0.49P is highly doped with p-type dopant (Zn, Mg, Be, C) or n-type dopant (Si, Se, Te) to produce non-radiative recombination level in the upper and lower barrier layers. Carriers injected into the quantum well layer not only recombine radiatively therein and also recombine nonradiatively at boundaries of the upper barrier layer and the lower barrier layer, remarkably increasing recombination velocity of carriers and dramatically improving the response characteristic.
    Type: Grant
    Filed: September 10, 2001
    Date of Patent: September 9, 2003
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Hiroshi Nakatsu, Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama
  • Patent number: 6548824
    Abstract: A semiconductor light emitting device has in sequence on a semiconductor substrate, a multilayer reflection film, a semiconductor layer, and a quantum well active layer. A distance between an upper surface of the multilayer reflection film and a lower surface of the quantum well active layer is 2&lgr;/n or less, where &lgr; is a light emission wavelength and n is an average refractive index of the semiconductor layer disposed in between the multilayer reflection film and the quantum well active layer. A phase difference between a reflected ray of light reflected by the multilayer reflection film and an emitted ray of light from the quantum well active layer is a multiple of 2&pgr;. In an emission spectrum of the semiconductor light emitting device, two troughs caused by interference between the emitted ray of light and the reflected ray of light appear in the both sides of a main peak.
    Type: Grant
    Filed: June 19, 2001
    Date of Patent: April 15, 2003
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Hiroyuki Hosoba, Tetsurou Murakami
  • Publication number: 20030038284
    Abstract: A semiconductor light emitting device has in sequence on a semiconductor substrate, a multilayer reflection film, a semiconductor layer, and a quantum well active layer. A distance between an upper surface of the multilayer reflection film and a lower surface of the quantum well active layer is 2&lgr;/n or less, where &lgr; is a light emission wavelength and n is an average refractive index of the semiconductor layer disposed in between the multilayer reflection film and the quantum well active layer. A phase difference between a reflected ray of light reflected by the multilayer reflection film and an emitted ray of light from the quantum well active layer is a multiple of 2&pgr;. In an emission spectrum of the semiconductor light emitting device, two troughs caused by interference between the emitted ray of light and the reflected ray of light appear in the both sides of a main peak.
    Type: Application
    Filed: October 16, 2002
    Publication date: February 27, 2003
    Applicant: Sharp Kabushiki Kaisha
    Inventors: Takahisa Kurahashi, Hiroshi Nakatsu, Hiroyuki Hosoba, Tetsurou Murakami
  • Patent number: 6501101
    Abstract: A light emitting diode comprising a multiple quantum well (MQW) layer as an active layer and a reflecting layer below the active layer, wherein the number and/or total thickness of well layers in the MQW layer is determined such that the MQW layer shows an external quantum efficiency higher than that of an MQW layer including a single well layer.
    Type: Grant
    Filed: June 19, 2001
    Date of Patent: December 31, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Tetsurou Murakami, Takahisa Kurahashi, Shouichi Ohyama, Hiroshi Nakatsu