Patents by Inventor Ken Nakahara
Ken Nakahara 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: 20090045393Abstract: There are provided a nitride semiconductor device having a structure capable of improving crystallinity of grown nitride semiconductor, carrying out easily removing a substrate, and dividing into chips very easily, by using zinc oxide based compound having excellent processability as a substrate, and a method for manufacturing the same. In case that a nitride semiconductor device is formed by laminating nitride semiconductor layers on a substrate (1), the substrate (1) is made of MgxZn1-xO (0<x?0.5), a first nitride semiconductor layer (2) made of InyGa1-yN (0?y?0.5) is provided in contact with the substrate, and nitride semiconductor layers (3) to (7) are laminated on the first nitride semiconductor layer so as to form the semiconductor device.Type: ApplicationFiled: May 8, 2006Publication date: February 19, 2009Applicant: Rohm Co., Ltd.Inventor: Ken Nakahara
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Publication number: 20090034568Abstract: There is provided a zinc oxide based compound semiconductor device in which drive voltage is not raised, property of crystal is satisfactory and device characteristics is excellent, even when the semiconductor device is formed by forming a lamination portion having a hetero junction of the ZnO based compound semiconductor layers. The zinc oxide based compound semiconductor device includes a substrate (1) made of MgxZn1-xO (0?x?0.5), the principal plane of which is a plane A (11-20) or a plane M (10-10), and single crystal layers (2) to (6) made of zinc oxide based compound semiconductor, which are epitaxially grown on the principal plane of the substrate (1) in such orientation that a plane parallel to the principal plane is a plane {11-20} or a plane {10-10} and a plane perpendicular to the principal plane is a plane {0001}.Type: ApplicationFiled: March 23, 2006Publication date: February 5, 2009Applicant: ROHM CO., LTD.Inventors: Ken Nakahara, Kentaro Tamura
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Publication number: 20090026475Abstract: Concaves and convexes are formed in a light transmitting conductive layer provided on a surface of a light emitting device made of nitride semiconductor, thereby light emitted from a light emitting layer is totally reflected repeatedly in a semiconductor lamination portion and a substrate and can be effectively taken out without attenuation, and external quantum efficiency can be improved. A semiconductor lamination portion (6) is formed by laminating nitride semiconductor layers including an n-type layer (3) and a p-type layer (5) on one side of a substrate (1) so as to form a light emitting layer, and a light transmitting conductive layer (7) is provided at a surface side of the semiconductor lamination portion. A concave-convex pattern, i.e., concaves (7a), is provided on a surface of the light transmitting conductive layer.Type: ApplicationFiled: December 28, 2006Publication date: January 29, 2009Applicant: ROHM CO., LTD.Inventors: Atsushi Yamaguchi, Ken Nakahara
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Publication number: 20090026468Abstract: In a semiconductor light emitting element, a p-type layer (220), an active layer (230) and an n-type layer (240) are laminated on a substrate in this order. The n-type layer (240) is formed with a rectangular n-side electrode (241) whose width in one direction is equal to that of the n-type layer (240). The thickness t of the n-type layer (240) satisfies Formula 1 below. The semiconductor light emitting element includes a side surface (270) extending in the lamination direction and formed with a plurality of projections (271). Supposing that the wavelength of the light from the active-layer (230) is ? and the index of refraction of the n-type layer (240) or the p-type layer (220) is n, the average WA of widths at bottoms of the projections is set to satisfy WA??/n.Type: ApplicationFiled: February 22, 2007Publication date: January 29, 2009Applicant: ROHM CO., LTD.Inventors: Mitsuhiko Sakai, Tadahiro Okazaki, Ken Nakahara
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Publication number: 20090029499Abstract: Provided is a method for manufacturing a nitride semiconductor light emitting element. In the method, when an isolation trench for chip isolation and for laser lift-off is formed, a degradation-free nitride semiconductor light emitting element with high luminance can be formed without doing any damages to a light emitting region. In an n type nitride semiconductor layer 2, a step A is formed in a region beyond an active layer 3 looked from a p side. A protective insulating film 6 covers, to a portion of the step A, side surfaces of a part of the n type nitride semiconductor layer 2, the active layer 3, a p type nitride semiconductor layer 4, and a p electrode 5 as well as a part of an upper side of the p electrode 5. With a structure in which side surfaces of a chip are covered with the protective insulating film 6, when the isolation trench for chip isolation and for laser lift-off is formed using etching, the active layer 3 and the like are not exposed to etching gas for a long time.Type: ApplicationFiled: December 20, 2006Publication date: January 29, 2009Applicant: ROHM CO., LTD.Inventor: Ken Nakahara
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Publication number: 20080308836Abstract: There are provided a nitride semiconductor device such as a nitride semiconductor light emitting device, a transistor device or the like, obtained by forming a buffer layer of a single crystal of the nitride semiconductor, in which both a-axis and c-axis are aligned, directly on a substrate lattice-mismatched with the nitride semiconductor without forming an amorphous low temperature buffer layer, and growing epitaxially the nitride semiconductor layer on the buffer layer of the single crystal. In this device, a single crystal buffer layer (2), made of a single crystal of AlxGayIn1-x-yN (0?x?1, 0?y?1 and 0?x+y?1), in which a-axis and c-axis are aligned, is directly formed on a substrate (1) lattice-mismatched with nitride semiconductor, and a nitride semiconductor layer (3) is epitaxially grown on the buffer layer (2) of the single crystal. The buffer layer of the single crystal can be formed by the use of a PLD method.Type: ApplicationFiled: January 26, 2006Publication date: December 18, 2008Applicant: ROHM CO., LTD.Inventors: Ken Nakahara, Kentaro Tamura
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Publication number: 20080283863Abstract: In order to emit a light from an electrode side, in semiconductor light emitting devices such as LED and the like, and liquid crystal, the electrode is formed of a transparent material so as to transmit a light through the transparent electrode and exit the light. A ZnO, which constitutes a material for the transparent electrode, is subject to erosion by acid and alkali, thus, as the case may cause loss of a reliability of the electrode under the influence of ion-containing moisture. In order to solve such a problem, this invention has as its aim a transparent electrode film provided with stability capable of preventing any degradation under the influence of any ion-containing moisture, while being kept acid-proof and alkali-proof. In order to accomplish the above-mentioned aim, this invention provides a transparent electrode made up of a ZnO as its main material, wherein its surface is covered with a Mg-doped ZnO film.Type: ApplicationFiled: July 21, 2008Publication date: November 20, 2008Applicant: ROHM CO., LTD.Inventor: Ken NAKAHARA
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Publication number: 20080258166Abstract: There is provided a semiconductor light emitting semiconductor device including an n-side electrode which has a structure capable of stably suppressing the contact resistance between the n-side electrode and a nitride semiconductor layer. Further, there is provided a light emitting device and a manufacturing method wherein an ohmic contact between the n-side electrode and the nitride semiconductor layer can be obtained by a simple manufacturing process, and the n-side electrode has an Au layer on a top surface to facilitate wire bonding. Semiconductor layers (2-8) to form a light emitting layer are laminated on a surface of a substrate (1) made of, for example, a sapphire (Al2O3 single crystal) or the like and a p-side electrode (10) is formed on the surface thereof thorough a light transmitting conductive layer (9). An n-side electrode (11) is formed on an exposed surface of an n-type layer (4), exposed by removing a part of the semiconductor layers (4-8) by etching.Type: ApplicationFiled: May 10, 2005Publication date: October 23, 2008Inventors: Mitsuhiko Sakai, Shinichi Kohda, Masayuki Sonobe, Ken Nakahara
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Publication number: 20080245297Abstract: A container of a material supply apparatus is configured of a crucible and an orifice. The crucible has a cylindrical shape, a rectangular-column shape or the like, and is hollow. Heat sources such as heaters are disposed around the crucible. The orifice including an opening is provided on a side of the crucible in a material element supplying direction. The orifice includes a pipe portion that extends in the material element supplying direction. The opening is formed on a tip of the pipe portion. An opening area of the pipe portion is formed to become gradually narrower towards the material element supplying side, namely in a direction of the opening.Type: ApplicationFiled: March 28, 2008Publication date: October 9, 2008Applicant: ROHM CO., LTD.Inventors: Ken Nakahara, Hiroyuki Yuji, Kentaro Tamura, Shunsuke Akasaka, Masashi Kawasaki, Akira Ohtomo, Atsushi Tsukazaki
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Patent number: 7417263Abstract: In order to emit a light from an electrode side, in semiconductor light emitting devices such as LED and the like, and liquid crystal, the electrode is formed of a transparent material so as to transmit a light through the transparent electrode and exit the light. A ZnO, which constitutes a material for the transparent electrode, is subject to erosion by acid and alkali, thus, as the case may cause loss of a reliability of the electrode under the influence of ion-containing moisture. In order to solve such a problem, this invention has as its aim a transparent electrode film provided with stability capable of preventing any degradation under the influence of any ion-containing moisture, while being kept acid-proof and alkali-proof. In order to accomplish the above-mentioned aim, this invention provides a transparent electrode made up of a ZnO as its main material, wherein its surface is covered with a Mg-doped ZnO film.Type: GrantFiled: December 30, 2003Date of Patent: August 26, 2008Assignee: Rohm Co., Ltd.Inventor: Ken Nakahara
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Publication number: 20080187776Abstract: Provided is a multilayer substrate having the configuration in which a multilayer film is formed on a principal surface opposite to a principal surface in the oxide-thin-film lamination direction in a translucent substrate. The multilayer film is formed by sequentially laminating a dielectric film, Au (gold) film, and oxide film in this order from the translucent substrate. On the principal surface opposite to the principal surface on which the oxide thin film is disposed, the multilayer film containing the Au film is formed, the Au film can reflect and block the excessive infrared light from a substrate holder or a heat source at the time of growth. As a result, temperature can be accurately measured.Type: ApplicationFiled: February 6, 2008Publication date: August 7, 2008Applicant: ROHM CO., LTD.Inventors: Ken Nakahara, Hiroyuki Yuji, Kentaro Tamura, Shunsuke Akasaka, Yoshio Nishimoto, Masashi Kawasaki, Akira Ohtomo, Atsushi Tsukazaki
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Publication number: 20080073659Abstract: A semiconductor light emitting device is provided, in which the light emitting efficiency of a LED is improved. A semiconductor light emitting device (11) includes a light emitting layer (16) made of a GaN-based semiconductor sandwiched with an n-type GaN-based semiconductor layer (17) and a p-type GaN-based semiconductor layer (15), and a ZnO-based or an ITO transparent electrode layer (14). Further, a value of an equation represented by 3t/(A/?)1/2?3(t/(A/?)1/2)2+(t/(A/?)1/2)3 is 0.1 or more, where a thickness of the transparent electrode layer is represented by t and an area of the light emitting layer (light emitting area) of the light emitting device (11) is represented by A. The light emitting efficiency is improved using the transparent electrode layer (14) having an optimum thickness to the light emitting area.Type: ApplicationFiled: September 7, 2005Publication date: March 27, 2008Inventors: Kentaro Tamura, Ken Nakahara
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Patent number: 7292382Abstract: A light control unit comprises: a substrate; an insulating film; a first transistor; a reflecting film formed on the insulating film; a light modulating film formed on the reflecting film; a plurality of pairs of electrodes arranged two-dimensionally on the light modulating film; and a polarizing plate formed on a first electrode. Here, the light modulating film is made of a material that varies in refractive index in accordance with the intensity of an electric field applied thereto. For such a material, PLZT containing Pb, Zr, Ti, and La as constituent elements may be used.Type: GrantFiled: February 3, 2006Date of Patent: November 6, 2007Assignee: Rohm Co., Ltd.Inventors: Yoshikazu Fujimori, Ken Nakahara, Takashi Nakamura
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Patent number: 7196348Abstract: Although there is provided a high light transmittance of an emitted light by a ITO electrode film conventionally employed, there occurs a formation of a Schottky type contact between the ITO electrode film and a p type GaN system semiconductor layer, thus resulting in a not uniform flow of an electric current. It is an object of the present invention to provide a semiconductor light emitting device constituted by forming a transparent electrode, which facilitates acquiring an ohmic property, to be replaced by an ITO electrode film, at the light extracting or light exit side of the GaN system semiconductor light emitting device, so as to improve a light emission efficiency and a radiation extracting efficiency or a light exit efficiency of a GaN system semiconductor light emitting device.Type: GrantFiled: January 21, 2004Date of Patent: March 27, 2007Assignee: Rohm Co., Ltd.Inventor: Ken Nakahara
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Patent number: 7132691Abstract: It has a structure in which an active layer (5) that emits light by electric current injection is sandwiched between an n-type cladding layer (4) and a p-type cladding layer (6) made of materials having a larger band gap than the active layer (5), wherein the active layer (5) is made, for example, of CdxZn1?xO (0?x<1). It is further more preferable if the cladding layers (4), (6) are made, for example, of MgyZn1?yO (0?y<1). This narrows the band gap of the ZnO materials, and an oxide semiconductor capable of being wet-etched, easy to handle with, and excellent in crystallinity can be used as a material for an active layer or a cladding layer of a semiconductor light emitting device such as a blue light emitting diode or a blue laser diode in which an active layer is sandwiched between cladding layers, so that a blue semiconductor light emitting device being excellent in light emission characteristics can be obtained.Type: GrantFiled: September 9, 1999Date of Patent: November 7, 2006Assignee: Rohm Co., Ltd.Inventors: Tetsuhiro Tanabe, Ken Nakahara
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Publication number: 20060193233Abstract: A light control apparatus including a plurality of two-dimensionally arranged pixels, each of the plurality of pixels comprising a first storage element which stores a luminance value of a present frame for the pixel; a second storage element which stores a preliminary luminance value for the pixel; and a switching element which changes the luminance value for the pixel by transferring the luminance value stored in the second storage element to the first storage element.Type: ApplicationFiled: March 9, 2006Publication date: August 31, 2006Inventors: Yoshikazu Fujimori, Ken Nakahara, Takashi Nakamura
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Publication number: 20060126360Abstract: A light control unit comprises: a substrate; an insulating film; a first transistor; a reflecting film formed on the insulating film; a light modulating film formed on the reflecting film; a plurality of pairs of electrodes arranged two-dimensionally on the light modulating film; and a polarizing plate formed on a first electrode. Here, the light modulating film is made of a material that varies in refractive index in accordance with the intensity of an electric field applied thereto. For such a material, PLZT containing Pb, Zr, Ti, and La as constituent elements may be used.Type: ApplicationFiled: February 3, 2006Publication date: June 15, 2006Inventors: Yoshikazu Fujimori, Ken Nakahara, Takashi Nakamura
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Patent number: 7002179Abstract: In order to provide ZnO system semiconductor devices having a stable p-type ZnO layer, a ZnO thin film is doped with nitrogen atoms having a high concentration. By fabricating the stable p-type ZnO layer, combinations with n-type ZnO layers easy of fabrication, or combinations with different compositions of p-type layers or n-type layers are made possible, thereby it enables to provide various configurations of ZnO system semiconductor devices. A ZnO system semiconductor device according to the present invention is characterized in that in a semiconductor device comprising one or more layers of n-type layer and p-type layers respectively, at least one layer of said p-type layers is (are) formed of the Zn-polar ZnO system semiconductor film doped with nitrogen atoms such that the thin film growth direction of said Zn-polar ZnO system semiconductor film is conformed to the direction of Zn polarity (0001).Type: GrantFiled: February 4, 2004Date of Patent: February 21, 2006Assignee: Rohm Co., Ltd.Inventor: Ken Nakahara
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Patent number: 6987029Abstract: A light emitting device includes a silicon substrate (1), a silicon nitride film (2) formed on the surface of the silicon substrate (1), at least an n-type layer (3), (4) and a p-type layer (6), (7) which are formed on the silicon nitride film (2) and also which are made of a ZnO based compound semiconductor, and a semiconductor layer lamination (11) in which layers are laminated to form a light emitting layer. Preferably this silicon nitride film (2) is formed by thermal treatment conducted in an atmosphere containing nitrogen such as an ammonium gas. Also, in another embodiment, a light emitting device is formed by growing a ZnO based compound semiconductor layer on a main face of a sapphire substrate, the main face being perpendicular to the C-face thereof. As a result, it is possible to obtain a device using a ZnO based compound with high properties such as an LED very excellent in crystallinity and having a high light emitting efficiency.Type: GrantFiled: November 17, 2003Date of Patent: January 17, 2006Assignees: National Institute of Advanced Industrial Science and Technology, Rohm Co., Ltd.Inventors: Shigeru Niki, Paul Fons, Kakuya Iwata, Tetsuhiro Tanabe, Hidemi Takasu, Ken Nakahara
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Publication number: 20050247954Abstract: A light emitting device includes a silicon substrate (1), a silicon nitride film (2) formed on the surface of the silicon substrate (1), at least an n-type layer (3), (4) and a p-type layer (6), (7) which are formed on the silicon nitride film (2) and also which are made of a ZnO based compound semiconductor, and a semiconductor layer lamination (11) in which layers are laminated to form a light emitting layer. Preferably this silicon nitride film (2) is formed by thermal treatment conducted in an atmosphere containing nitrogen such as an ammonium gas. Also, in another embodiment, a light emitting device is formed by growing a ZnO based compound semiconductor layer on a main face of a sapphire substrate, the main face being perpendicular to the C-face thereof. As a result, it is possible to obtain a device using a ZnO based compound with high properties such as an LED very excellent in crystallinity and having a high light emitting efficiency.Type: ApplicationFiled: June 27, 2005Publication date: November 10, 2005Inventors: Shigeru Niki, Paul Fons, Kakuya Iwata, Tetsuhiro Tanabe, Hidemi Takasu, Ken Nakahara