Patents by Inventor Shouichi Ohyama
Shouichi Ohyama 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).
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Patent number: 7495263Abstract: 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: GrantFiled: February 7, 2001Date of Patent: February 24, 2009Assignee: Sharp Kabushiki KaishaInventors: Takahisa Kurahashi, Hiroyuki Hosoba, Hiroshi Nakatsu, Tetsurou Murakami, Shouichi Ohyama
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Patent number: 7166865Abstract: 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: GrantFiled: October 5, 2004Date of Patent: January 23, 2007Assignee: Sharp Kabushiki KaishaInventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama, Hiroshi Nakatsu
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Publication number: 20050116309Abstract: A semiconductor light-emitting element has a semiconductor laminate including an active layer emitting light of a prescribed emission wavelength and a step located at an in-depth position beyond the active layer. The element also has a substrate transparent to the emission wavelength, a first electrode provided on a surface of the semiconductor laminate, and a second electrode provided on the step. The substrate transparent to the emission wavelength improves the external emission efficiency. The locations of the first and second electrodes substantially prevent current to flow through a direct connection interface between the semiconductor laminate and the substrate. Thereby, the element exhibits satisfactory electrical characteristics even when an incomplete junction attributed to hillock or the like is generated in the direct connection interface.Type: ApplicationFiled: October 25, 2004Publication date: June 2, 2005Inventors: Shouichi Ohyama, Tetsurou Murakamii, Takahisa Kurahashi, Osamu Yamamoto, Hiroshi Nakatsu
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Publication number: 20050093015Abstract: 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: ApplicationFiled: October 5, 2004Publication date: May 5, 2005Applicant: Sharp Kabushiki KaishaInventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama, Hiroshi Nakatsu
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Patent number: 6864514Abstract: A light emitting diode having, at least, an AlGaInP light emitting layer and a transparent electrode, wherein the transparent electrode is made of a ZnO film doped with a group III element or a compound thereof.Type: GrantFiled: December 3, 2003Date of Patent: March 8, 2005Assignee: Sharp Kabushiki KaishaInventors: Tetsuroh Murakami, Hiroshi Nakatsu, Takahisa Kurahashi, Shouichi Ohyama
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Patent number: 6849473Abstract: In a semiconductor light-emitting device, on an n-GaAs substrate are stacked an n-GaAs buffer layer, an n-cladding layer, an undoped active layer, a p-cladding layer, a p-intermediate band gap layer and a p-current diffusion layer. Further, a first electrode is formed under the n-GaAs substrate, and a second electrode is formed on the grown-layer side. In this process, a region of the p-intermediate band gap layer just under the second electrode is removed, the p-current diffusion layer is stacked in the removal region on the p-cladding layer, and a junction plane of the p-current diffusion layer and the p-cladding layer becomes high in resistance due to an energy band structure of type II. This semiconductor light-emitting device is capable of reducing ineffective currents with a simple construction and taking out light effectively to outside, thus enhancing the emission intensity.Type: GrantFiled: September 25, 2002Date of Patent: February 1, 2005Assignee: Sharp Kabushiki KaishaInventors: Kazuaki Sasaki, Junichi Nakamura, Shouichi Ohyama
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Patent number: 6822266Abstract: 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: GrantFiled: May 24, 2002Date of Patent: November 23, 2004Assignee: Sharp Kabushiki KaishaInventors: Takahisa Kurahashi, Hiroshi Nakatsu, Tetsurou Murakami, Shouichi Ohyama
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Patent number: 6815727Abstract: 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: GrantFiled: June 24, 2003Date of Patent: November 9, 2004Assignee: Sharp Kabushiki KaishaInventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama, Hiroshi Nakatsu
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Patent number: 6770915Abstract: In a semiconductor light-emitting element, a first DBR and a second DBR, with a specified spacing left between them, form a resonator, and a single quantum well active layer is positioned at the loop of a standing wave within this resonator. The single quantum well active layer is composed of a Ga0.5In0.5P well layer and a pair of (Al0.5Ga0.5)0.5In0.5P barrier layers, which sandwiches the Ga0.5In0.5P well layer therebetween. The impurity concentration of the (Al0.5Ga0.5)0.5In0.5P barrier layers is higher than that of the Ga0.5In0.5P well layer. For example, the impurity concentration of the Ga0.5In0.5P well layer is set to 2×1016 cm−3, while the impurity concentration of the (Al0.5Ga0.5)0.5In0.5P barrier layers is set to 2×1018 cm−3.Type: GrantFiled: April 17, 2003Date of Patent: August 3, 2004Assignee: Sharp Kabushiki KaishaInventors: Tetsuroh Murakami, Takahisa Kurahashi, Shouichi Ohyama, Hiroshi Nakatsu
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Publication number: 20040113170Abstract: A light emitting diode having, at least, an AlGaInP light emitting layer and a transparent electrode, wherein the transparent electrode is made of a ZnO film doped with a group III element or a compound thereof.Type: ApplicationFiled: December 3, 2003Publication date: June 17, 2004Applicant: SHARP KABUSHIKI KAISHAInventors: Tetsuroh Murakami, Hiroshi Nakatsu, Takahisa Kurahashi, Shouichi Ohyama
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Publication number: 20040036075Abstract: 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: ApplicationFiled: June 24, 2003Publication date: February 26, 2004Applicant: SHARP KABUSHIKI KAISHAInventors: Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama, Hiroshi Nakatsu
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Publication number: 20030197171Abstract: In a semiconductor light-emitting element, a first DBR and a second DBR, with a specified spacing left between them, form a resonator, and a single quantum well active layer is positioned at the loop of a standing wave within this resonator. The single quantum well active layer is composed of a Ga0.5In0.5P well layer and a pair of (Al0.5Ga0.5)0.5In0.5P barrier layers, which sandwiches the Ga0.5In0.5P well layer therebetween. The impurity concentration of the (Al0.5Ga0.5)0.5In0.5P barrier layers is higher than that of the Ga0.5In0.5P well layer. For example, the impurity concentration of the Ga0.5In0.5P well layer is set to 2×1016 cm−3, while the impurity concentration of the (Al0.5Ga0.5)0.5In0.5P barrier layers is set to 2×1018 cm−3.Type: ApplicationFiled: April 17, 2003Publication date: October 23, 2003Applicant: SHARP KABUSHIKI KAISHAInventors: Tetsuroh Murakami, Takahisa Kurahashi, Shouichi Ohyama, Hiroshi Nakatsu
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Patent number: 6617606Abstract: 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: GrantFiled: September 10, 2001Date of Patent: September 9, 2003Assignee: Sharp Kabushiki KaishaInventors: Hiroshi Nakatsu, Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama
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Publication number: 20030020080Abstract: In a semiconductor light-emitting device, on an n-GaAs substrate are stacked an n-GaAs buffer layer, an n-cladding layer, an undoped active layer, a p-cladding layer, a p-intermediate band gap layer and a p-current diffusion layer. Further, a first electrode is formed under the n-GaAs substrate, and a second electrode is formed on the grown-layer side. In this process, a region of the p-intermediate band gap layer just under the second electrode is removed, the p-current diffusion layer is stacked in the removal region on the p-cladding layer, and a junction plane of the p-current diffusion layer and the p-cladding layer becomes high in resistance due to an energy band structure of type II. This semiconductor light-emitting device is capable of reducing ineffective currents with a simple construction and taking out light effectively to outside, thus enhancing the emission intensity.Type: ApplicationFiled: September 25, 2002Publication date: January 30, 2003Inventors: Kazuaki Sasaki, Junichi Nakamura, Shouichi Ohyama
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Patent number: 6501101Abstract: 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: GrantFiled: June 19, 2001Date of Patent: December 31, 2002Assignee: Sharp Kabushiki KaishaInventors: Tetsurou Murakami, Takahisa Kurahashi, Shouichi Ohyama, Hiroshi Nakatsu
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Publication number: 20020185653Abstract: 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: ApplicationFiled: May 24, 2002Publication date: December 12, 2002Applicant: SHARP KABUSHIKI KAISHAInventors: Takahisa Kurahashi, Hiroshi Nakatsu, Tetsurou Murakami, Shouichi Ohyama
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Patent number: 6476421Abstract: In a semiconductor light-emitting device, on an n-GaAs substrate are stacked an n-GaAs buffer layer, an n-cladding layer, an undoped active layer, a p-cladding layer, a p-intermediate band gap layer and a p-current diffusion layer. Further, a first electrode is formed under the n-GaAs substrate, and a second electrode is formed on the grown-layer side. In this process, a region of the p-intermediate band gap layer just under the second electrode is removed, the p-current diffusion layer is stacked in the removal region on the p-cladding layer, and a junction plane of the p-current diffusion layer and the p-cladding layer becomes high in resistance due to an energy band structure of type II. This semiconductor light-emitting device is capable of reducing ineffective currents with a simple construction and taking out light effectively to outside, thus enhancing the emission intensity.Type: GrantFiled: April 20, 2001Date of Patent: November 5, 2002Assignee: Sharp Kabushiki KaishaInventors: Kazuaki Sasaki, Junichi Nakamura, Shouichi Ohyama
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Patent number: 6399965Abstract: There is provided a semiconductor light emitting device having improved adhesion of an electrode by reducing defects in a crystal surface. An n-type AlGaInP lower clad layer 12, an AlGaInP active layer 13, a p-type AlGaInP upper clad layer 14, a p-type AlGaInP intermediate layer 15 whose lattice matching rate &Dgr;a/a with GaAs is −3.3%, a p-type AlGaInP current diffusion layer 16 and a p-type electrode 17 are laminated on an n-type GaAs substrate 11 and an n-type electrode 18 is provided on the n-type GaAs substrate 11. Thus, the number of crystal defects in the crystal surface can be reduced to 20 or less per one LED by setting the value of the lattice matching rate &Dgr;a/a of the intermediate layer 15 to be −3.3%, which is lower than −2.5%. As a result, adhesion of the p-type electrode 17 formed on the current diffusion layer 16 is improved and thereby the yield of LED can be enhanced.Type: GrantFiled: January 11, 2001Date of Patent: June 4, 2002Assignee: Sharp Kabushiki KaishaInventors: Junichi Nakamura, Kazuaki Sasaki, Shouichi Ohyama
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Publication number: 20020050590Abstract: 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: ApplicationFiled: June 19, 2001Publication date: May 2, 2002Inventors: Tetsurou Murakami, Takahisa Kurahashi, Shouichi Ohyama, Hiroshi Nakatsu
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Publication number: 20020038866Abstract: 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: ApplicationFiled: September 10, 2001Publication date: April 4, 2002Inventors: Hiroshi Nakatsu, Takahisa Kurahashi, Tetsurou Murakami, Shouichi Ohyama