Patents by Inventor Noritaka Muraki
Noritaka Muraki 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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Publication number: 20090184329Abstract: An object of the present invention is to provide a transparent positive electrode for use in a face-up-type chip which can emit intense light even using a low drive voltage. The inventive positive electrode for a semiconductor light-emitting device comprises a transparent electrode formed on a semiconductor layer and a bonding pad electrode formed on the transparent electrode, wherein the bonding pad electrode has a reflecting layer that is in contact with at least the transparent electrode.Type: ApplicationFiled: July 28, 2005Publication date: July 23, 2009Applicant: SHOWA DENKO K.K.Inventors: Hisayuki Miki, Noritaka Muraki, Munetaka Watanabe
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Publication number: 20090152585Abstract: It is an object of the present invention to provide a gallium nitride-based compound semiconductor light-emitting device that is excellent in light output efficiency and needs only a low driving voltage (Vf). The inventive gallium nitride-based compound semiconductor light-emitting device includes an n-type semiconductor layer, a light-emitting layer and a p-type semiconductor layer formed of a gallium nitride-based compound semiconductor and stacked in this order on a substrate, and positive and negative electrodes so arranged as to be in contact with the p-type semiconductor layer and the n-type semiconductor layer, respectively, wherein a region in which a p-type impurity and hydrogen atoms are co-present exists in the p-type semiconductor layer in contact with the positive electrode, and at least a portion, which is in contact with the p-type semiconductor layer, of the positive electrode, is formed of an n-type electro-conductive light transmitting material.Type: ApplicationFiled: September 5, 2006Publication date: June 18, 2009Applicant: SHOWA DENKO K.K.Inventors: Hironao Shinohara, Hisayuki Miki, Noritaka Muraki
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Patent number: 7498611Abstract: A transparent electrode for a gallium nitride-based compound semiconductor light-emitting device includes a p-type semiconductor layer (5), a contact metal layer (1) formed by ohmic contact on the p-type semiconductor layer, an current diffusion layer (12) formed on the contact metal layer and having a lower magnitude of resistivity on the plane of the transparent electrode than the contact metal, and a bonding pad (13) formed on the current diffusion layer. The transparent electrode is at an advantage in widening the surface of light emission in the p-type semiconductor layer, decreasing the operation voltage in the forward direction, and enabling the bonding pad to provide excellent adhesive strength.Type: GrantFiled: July 27, 2005Date of Patent: March 3, 2009Assignee: Showa Denko K.K.Inventors: Nobuo Eitoh, Noritaka Muraki, Hisayuki Miki, Munetaka Watanabe
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Publication number: 20090045434Abstract: A gallium nitride-based compound semiconductor light-emitting device including a positive electrode having openings, which is excellent in light extraction efficiency. The gallium nitride-based compound semiconductor light-emitting device includes a substrate; an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer, the layers being formed of a gallium nitride-based compound semiconductor and being stacked in this order on the substrate; a positive electrode which is provided so as to contact the p-type semiconductor layer; and a negative electrode which is provided so as to contact the n-type semiconductor layer, where the positive electrode is a positive electrode having openings, and at least a portion of the surface of the p-type semiconductor layer corresponding to the openings are roughened surface derived from spherical particulates.Type: ApplicationFiled: December 13, 2006Publication date: February 19, 2009Applicant: SHOWA DENKO K.K.Inventors: Noritaka Muraki, Hironao Shinohara
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Publication number: 20080315237Abstract: This gallium nitride-based compound semiconductor light emitting device includes an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer that are composed of gallium nitride-based compound semiconductors and are deposited in that order on a substrate, and further includes a negative electrode and a positive electrode that are in contact with the n-type semiconductor layer and the p-type semiconductor layer, respectively, wherein the positive electrode has a translucent electrode composed of a three-layer structure including a contact metal layer that contacts at least the p-type semiconductor layer, a current diffusion layer provided on the contact metal layer and having conductivity greater than that of the contact metal layer, and a bonding pad layer provided on the current diffusion layer, and a mixed positive electrode-metal layer including a metal that forms the contact metal layer is present in a positive electrode side surface of the p-type semiconductor layer.Type: ApplicationFiled: May 19, 2005Publication date: December 25, 2008Inventors: Koji Kamei, Munetaka Watanabe, Noritaka Muraki, Yasushi Ohno
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Patent number: 7402841Abstract: An object of the present invention is to provide a light-permeable electrode for use in a gallium nitride-based compound semiconductor light-emitting device, the electrode having improved light permeability and contact resistance. The inventive electrode comprises a light-permeable first layer which is in contact with a surface of a p-contact layer in a gallium nitride-based compound semiconductor light-emitting device and which is capable of providing ohmic contact, and a second layer which is in contact with a part of a surface of said p-contact layer, wherein the first layer comprises a metal, or an alloy of two or more metals, selected from a first group consisting of Au, Pt, Pd, Ni, Co, and Rh, and the second layer comprises an oxide of at least one metal selected from a second group consisting of Ni, Ti, Sn, Cr, Co, Zn, Cu, Mg, and In.Type: GrantFiled: September 21, 2004Date of Patent: July 22, 2008Assignee: Showa Denko K.K.Inventors: Hideki Tomozawa, Mineo Okuyama, Noritaka Muraki, Soichiro Masuyama
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Patent number: 7402830Abstract: The inventive gallium nitride compound semiconductor light-emitting device comprises a substrate; an n-type semiconductor layer, a light-emitting layer, a p-type semiconductor layer, the layers being successively provided atop the substrate and being formed of a gallium nitride compound semiconductor; a negative electrode provided on the n-type semiconductor layer at a certain portion thereof, the portion being exposed by partial, depthwise removal of the light-emitting layer and the p-type semiconductor layer altogether through reactive ion etching; and a positive electrode provided on the remaining p-type semiconductor layer, wherein the gallium nitride compound semiconductor light-emitting device is produced through reactive ion etching by use of silicon tetrachloride as the sole etching gas.Type: GrantFiled: March 15, 2005Date of Patent: July 22, 2008Assignee: Show a Denko K.K.Inventors: Munetaka Watanabe, Noritaka Muraki, Yasushi Ohno
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Patent number: 7399994Abstract: A transparent electrode for use in a gallium nitride-based compound semiconductor light-emitting device having an emission wavelength of 440 nm or less, includes a metal layer disposed in contiguity to a p-type semiconductor layer and a current diffusion layer disposed on the metal layer. The transparent electrode contains substantially no Au in the whole region thereof. The metal layer contains any one element selected from the group consisting of Pt, Ir, Ru and Rh as a main component. The current diffusion layer contains any one element selected from the group consisting of Pt, Ir, Ru and Rh as a main component except for the case where the metal layer and the current diffusion layer have the same composition. It is possible to provide a white light-emitting device provided with the transparent electrode, a white light-emitting lamp using the white light-emitting device and a lighting fixture using the white light-emitting lamp.Type: GrantFiled: February 7, 2006Date of Patent: July 15, 2008Assignee: Showa Denka K.K.Inventors: Noritaka Muraki, Munetaka Watanabe, Yasushi Ohono, Hisayuki Miki
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Publication number: 20080048172Abstract: A gallium nitride compound semiconductor light-emitting device includes a crystalline substrate (10), a light-emiting layer (15) of a quantum well structure which is formed of a gallium nitride compound semiconductor barrier layer and a gallium nitride compound semiconductor well layer, which light-emitting layer is provided on a second side of the crystalline substrate, a contact layer (17) formed of a Group III-V compound semiconductor for providing an Ohmic electrode for supplying device operation current to the light-emitting layer, and an Ohmic electrode (18) which is provided on the contact layer and has an aperture through which a portion of the contact layer is exposed. The Ohmic electrode exhibits light permeability with respect to light emitted from the light-emitting layer. The well layer contains a thick portion having a large thickness and a thin portion having a small thickness.Type: ApplicationFiled: January 28, 2005Publication date: February 28, 2008Applicant: SHOWA DENKO K.K.Inventors: Noritaka Muraki, Munetaka Watanabe, Hisayuki Miki, Yasushi Ohno
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Publication number: 20080042159Abstract: A transparent electrode for a gallium nitride-based compound semiconductor light-emitting device includes a p-type semiconductor layer (5), a contact metal layer (1) formed by ohmic contact on the p-type semiconductor layer, an current diffusion layer (12) formed on the contact metal layer and having a lower magnitude of resistivity on the plane of the transparent electrode than the contact metal, and a bonding pad (13) formed on the current diffusion layer. The transparent electrode is at an advantage in widening the surface of light emission in the p-type semiconductor layer, decreasing the operation voltage in the forward direction, and enabling the bonding pad to provide excellent adhesive strength.Type: ApplicationFiled: July 27, 2005Publication date: February 21, 2008Applicant: SHOWA DENKO K.KInventors: Nobuo Eitoh, Noritaka Muraki, Hisayuki Miki, Munetaka Watanabe
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Publication number: 20070200129Abstract: An object of the present invention is to provide a positive electrode having high transparency, low contact resistance and excellent current diffusibility and not requiring electron beam irradiation, high-temperature annealing or heat treatment, for alloying, in an oxygen atmosphere. The inventive transparent positive electrode for gallium nitride-based compound semiconductor light-emitting devices comprises a contact metal layer in contact with a p-type semiconductor layer, a current diffusing layer on the contact metal layer, the current diffusing layer having an electrical conductivity larger than that of the contact metal layer, and a bonding pad layer on the current diffusing layer.Type: ApplicationFiled: April 28, 2005Publication date: August 30, 2007Applicant: SHOWA DENKO K.K.Inventors: Munetaka Watanabe, Noritaka Muraki, Koji Kamei, Yasushi Ohno
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Publication number: 20070187666Abstract: An object of the present invention is to provide a gallium nitride compound semiconductor light-emitting device having excellent heat resistance, which device is resistive to an increase in the forward operation voltage (VF) caused by mild heating performed after formation of the light-emitting device (e.g., heating to about 300° C. during mounting of the light-emitting device).Type: ApplicationFiled: March 15, 2005Publication date: August 16, 2007Applicant: SHOWA DENKO K.K.Inventors: Munetaka Watanabe, Noritaka Muraki, Yasushi Ohno
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Publication number: 20070040183Abstract: An object of the present invention is to provide a light-permeable electrode for use in a gallium nitride-based compound semiconductor light-emitting device, the electrode having improved light permeability and contact resistance. The inventive electrode comprises a light-permeable first layer which is in contact with a surface of a p-contact layer in a gallium nitride-based compound semiconductor light-emitting device and which is capable of providing ohmic contact, and a second layer which is in contact with a part of a surface of said p-contact layer, wherein the first layer comprises a metal, or an alloy of two or more metals, selected from a first group consisting of Au, Pt, Pd, Ni, Co, and Rh, and the second layer comprises an oxide of at least one metal selected from a second group consisting of Ni, Ti, Sn, Cr, Co, Zn, Cu, Mg, and In.Type: ApplicationFiled: September 21, 2004Publication date: February 22, 2007Inventors: Hideki Tomozawa, Mineo Okuyama, Noritaka Muraki, Soichiro Masuyama
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Publication number: 20060175682Abstract: A transparent electrode for use in a gallium nitride-based compound semiconductor light-emitting device having an emission wavelength of 440 nm or less, includes a metal layer disposed in contiguity to a p-type semiconductor layer and a current diffusion layer disposed on the metal layer. The transparent electrode contains substantially no Au in the whole region thereof. The metal layer contains any one element selected from the group consisting of Pt, Ir, Ru and Rh as a main component. The current diffusion layer contains any one element selected from the group consisting of Pt, Ir, Ru and Rh as a main component except for the case where the metal layer and the current diffusion layer have the same composition. It is possible to provide a white light-emitting device provided with the transparent electrode, a white light-emitting lamp using the white light-emitting device and a lighting fixture using the white light-emitting lamp.Type: ApplicationFiled: February 7, 2006Publication date: August 10, 2006Inventors: Noritaka Muraki, Munetaka Watanabe, Yasushi Ohono, Hisayuki Miki
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Patent number: 7057210Abstract: An electrode for a light-emitting semiconductor device includes a light-permeable electrode formed to come into contact with the surface of the semiconductor, and a wire-bonding electrode that is in electrical contact with the light-permeable electrode and is formed to come into partial contact with the surface of the semiconductor with at least a region in contact with the semiconductor having a higher contact resistance per unit area with respect to the semiconductor than a region of the light-permeable electrode in contact with the semiconductor.Type: GrantFiled: March 16, 2004Date of Patent: June 6, 2006Assignee: Showa Denko K.K.Inventors: Hisayuki Miki, Takashi Udagawa, Noritaka Muraki, Mineo Okuyama
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Publication number: 20040232429Abstract: An electrode for a light-emitting semiconductor device includes a light-permeable electrode formed to come into contact with the surface of the semiconductor, and a wire-bonding electrode that is in electrical contact with the light-permeable electrode and is formed to come into partial contact with the surface of the semiconductor with at least a region in contact with the semiconductor having a higher contact resistance per unit area with respect to the semiconductor than a region of the light-permeable electrode in contact with the semiconductor.Type: ApplicationFiled: June 21, 2004Publication date: November 25, 2004Applicant: SHOWA DENKO K.K.Inventors: Hisayuki Miki, Takashi Udagawa, Noritaka Muraki, Mineo Okuyama
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Patent number: 6800501Abstract: An electrode for a light-emitting semiconductor device includes a light-permeable electrode formed to come into contact with the surface of the semiconductor, and a wire-bonding electrode that is in electrical contact with the light-permeable electrode and is formed to come into partial contact with the surface of the semiconductor with at least a region in contact with the semiconductor having a higher contact resistance per unit area with respect to the semiconductor than a region of the light-permeable electrode in contact with the semiconductor.Type: GrantFiled: May 2, 2002Date of Patent: October 5, 2004Assignee: Showa Denko K.K.Inventors: Hisayuki Miki, Takashi Udagawa, Noritaka Muraki, Mineo Okuyama
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Publication number: 20040173809Abstract: An electrode for a light-emitting semiconductor device includes a light-permeable electrode formed to come into contact with the surface of the semiconductor, and a wire-bonding electrode that is in electrical contact with the light-permeable electrode and is formed to come into partial contact with the surface of the semiconductor with at least a region in contact with the semiconductor having a higher contact resistance per unit area with respect to the semiconductor than a region of the light-permeable electrode in contact with the semiconductor.Type: ApplicationFiled: March 16, 2004Publication date: September 9, 2004Applicant: SHOWA DENKO K.K.Inventors: Hisayuki Miki, Takashi Udagawa, Noritaka Muraki, Mineo Okuyama
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Publication number: 20030006422Abstract: An electrode for a light-emitting semiconductor device includes a light-permeable electrode formed to come into contact with the surface of the semiconductor, and a wire-bonding electrode that is in electrical contact with the light-permeable electrode and is formed to come into partial contact with the surface of the semiconductor with at least a region in contact with the semiconductor having a higher contact resistance per unit area with respect to the semiconductor than a region of the light-permeable electrode in contact with the semiconductor.Type: ApplicationFiled: May 2, 2002Publication date: January 9, 2003Applicant: SHOWA DENKO K.K.Inventors: Hisayuki Miki, Takashi Udagawa, Noritaka Muraki, Mineo Okuyama
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Patent number: 6403987Abstract: An electrode for a light-emitting semiconductor device includes a light-permeable electrode formed to come into contact with the surface of the semiconductor, and a wire-bonding electrode that is in electrical contact with the light-permeable electrode and is formed to come into partial contact with the surface of the semiconductor with at least a region in contact with the semiconductor having a higher contact resistance per unit area with respect to the semiconductor than a region of the light-permeable electrode in contact with the semiconductor.Type: GrantFiled: October 24, 2000Date of Patent: June 11, 2002Assignee: Showa Denko K.K.Inventors: Hisayuki Miki, Takashi Udagawa, Noritaka Muraki, Mineo Okuyama