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).

  • Publication number: 20100065812
    Abstract: Provided is a nitride semiconductor light emitting element having an improved carrier injection efficiency from a p-type nitride semiconductor layer to an active layer by simple means from a viewpoint utterly different from the prior art. A buffer layer 2, an undoped GaN layer 3, an n-type GaN contact layer 4, an InGaN/GaN superlattice layer 5, an active layer 6, an undoped InGaN layer 7, and a p-type GaN-based contact layer 8 are stacked on a sapphire substrate 1. A p-electrode 9 is formed on the p-type GaN-based contact layer 8. An n-electrode 10 is formed on a surface where the n-type GaN contact layer 4 is exposed as a result of mesa-etching. The undoped InGaN layer 7 is included in an intermediate semiconductor layer formed between the p-type GaN-based contact layer 8 and a well layer closest to a p-side in the active layer having a quantum well structure.
    Type: Application
    Filed: May 26, 2006
    Publication date: March 18, 2010
    Applicant: ROHM CO., LTD.
    Inventors: Ken Nakahara, Norikazu Ito, Kazuaki Tsutsumi
  • Publication number: 20100040534
    Abstract: Provided are: a radical generating apparatus that increases a purity of emitted plasma atoms, prevents contamination with impurities, and is improved in controllability over ion concentration; and a ZnO-based thin film prevented from being contaminated with impurities. A high-frequency coil (4) is wound around an outer side of a discharging tube (10), and a terminal of the high-frequency coil (4) is connected to a high-frequency power source (9). The discharging tube (10) is constituted by a discharging cylinder (1), a lid (2) and a gas introducing bottom plate (3). Additionally, a support base (8) is provided, a support post (6) is arranged on the support base (8), and a shutter (5) is connected to the support post (6). With respect to shaded components, that is, the shutter (5), the lid (2), the discharging cylinder (1) and the gas introducing bottom plate (3), an entirety or a part thereof is formed of a silicon-based compound such as quartz.
    Type: Application
    Filed: March 14, 2008
    Publication date: February 18, 2010
    Applicant: ROHM Co., LTD.
    Inventors: Ken Nakahara, Hiroyuki Yuji, Kentaro Tamura, Shunsuke Akasaka, Masashi Kawasaki, Akira Ohtomo, Atsushi Tsukazaki
  • Publication number: 20100019257
    Abstract: There are provided a nitride semiconductor light emitting device having a structure enabling enhanced external quantum efficiency by effectively taking out light which is apt to repeat total reflection within a semiconductor lamination portion and a substrate and attenuate, and a method for manufacturing the same. A semiconductor lamination portion (6) including a first conductivity type layer and a second conductivity type layer, made of nitride semiconductor, is provided on a surface of the substrate (1) made of, for example, sapphire or the like. A first electrode (for example, p-side electrode (8)) is provided electrically connected to the first conductivity type layer (for example, p-type layer (5)) on a surface side of the semiconductor lamination portion (6), and a second electrode (for example, n-side electrode (9)) is provided electrically connected to the second conductivity type layer (for example, n-type layer (3)).
    Type: Application
    Filed: February 7, 2006
    Publication date: January 28, 2010
    Applicant: ROHM CO., LTD.
    Inventors: Mitsuhiko Sakai, Atsushi Yamaguchi, Ken Nakahara, Masayuki Sonobe, Tsuyoshi Tsutsui
  • Publication number: 20090294784
    Abstract: Provided are a nitride semiconductor light emitting element which does not suffer a damage on a light emitting region and has a high luminance without deterioration, even though the nitride semiconductor light emitting element is one in which electrodes are disposed opposite to each other and an isolation trench for chip separation and laser lift-off is formed by etching; and a manufacturing method thereof. An n-type nitride semiconductor layer 2 has a step, formed in a position beyond an active layer 3 when viewed from a p side. Up to the position of this step A, a protective insulating film 6 covers a part of the n-type nitride semiconductor layer 2, the active layer 3, a p-type nitride semiconductor layer 4, the side of a p electrode 5 and a part of the top side of the p electrode 5.
    Type: Application
    Filed: November 7, 2006
    Publication date: December 3, 2009
    Applicant: ROHM CO., LTD.
    Inventors: Ken Nakahara, Atsushi Yamaguchi
  • Publication number: 20090267048
    Abstract: Light extraction efficiency of a semiconductor light-emitting element is improved. A buffer layer, an n-type GaN layer, an InGaN emission layer, and a p-type GaN layer are laminated on a sapphire substrate in a semiconductor light-emitting element. A ZnO layer functioning as a transparent electrode is provided on the p-type GaN layer and concave portions are formed on a surface of the ZnO layer at two-dimensional periodic intervals. If a wavelength of light from the InGaN emission layer in the air is ?, an index of refraction of the ZnO layer at the wavelength ? is nz?, and a total reflection angle at an interface between the ZnO layer and a medium in contact therewith is ?z, a periodic interval Lz between adjacent concave portions is set in a range of ?/nz??Lz??/(nz?X(1?sin ?z)).
    Type: Application
    Filed: March 3, 2006
    Publication date: October 29, 2009
    Applicant: ROHM CO., LTD.
    Inventor: Ken Nakahara
  • Publication number: 20090267062
    Abstract: There is provided a zinc oxide based compound semiconductor device which, even when a semiconductor device is formed by forming a lamination portion having a hetero junction of ZnO based compound semiconductor layers, does not cause any rise in a drive voltage while ensuring p-type doping, and, at the same time, can realize good crystallinity and excellent device characteristics. ZnO based compound semiconductor layers (2) to (6) are epitaxially grown on the principal plane of a substrate (1) made of MgxZn1-xO (0?x<1). The principal plane of the substrate is a plane in which an A plane {11-20} or an M plane {10-10} is inclined in a direction of ?c axis.
    Type: Application
    Filed: September 21, 2006
    Publication date: October 29, 2009
    Inventors: Ken Nakahara, Yuji Hiroyuki
  • Patent number: 7605012
    Abstract: 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: Grant
    Filed: June 27, 2005
    Date of Patent: October 20, 2009
    Assignees: National Institute of Advanced Industrial Science & Tech., Rohm Co., Ltd.
    Inventors: Shigeru Niki, Paul Fons, Kakuya Iwata, Tetsuhiro Tanabe, Hidemi Takasu, Ken Nakahara
  • Patent number: 7582905
    Abstract: 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: Grant
    Filed: September 7, 2005
    Date of Patent: September 1, 2009
    Assignee: Rohm Co., Ltd.
    Inventors: Kentaro Tamura, Ken Nakahara
  • Publication number: 20090200545
    Abstract: Provided is a ZnO-based semiconductor device capable of growing a flat ZnO-based semiconductor layer on an MgZnO substrate having a main surface on the lamination side oriented in a c-axis direction. ZnO-based semiconductor layers 2 to 6 are epitaxially grown on an MgxZn1-xO (0?x?1) substrate 1 having a +C surface (0001), as a main surface, inclined at least in an m-axis direction. A p-electrode 8 is formed on the ZnO-based semiconductor layer 5, and an n-electrode 9 is formed on the underside of the MgxZn1-xO substrate 1. Thereby, steps regularly arranged in the m-axis direction can be formed on the surface of the MgxZn1-xO substrate 1, and a phenomenon called step bunching is prevented. Consequently, the flatness of a film of the semiconductor layers laminated on the substrate 1 can be improved.
    Type: Application
    Filed: June 8, 2007
    Publication date: August 13, 2009
    Applicant: ROHM Co., Ltd.
    Inventors: Ken Nakahara, Hiroyuki Yuji, Kentaro Tamura, Shunsuke Akasaka, Masashi Kawasaki, Atsushi Tsukazaki, Akira Ohtomo
  • Publication number: 20090179190
    Abstract: Provided is a nitride semiconductor light emitting element having an improved carrier injection efficiency from a p-type nitride semiconductor layer to an active layer by simple means from a viewpoint utterly different from the prior art. In the nitride semiconductor light emitting element, a buffer layer 2, an undoped GaN layer 3, an n-type GaN contact layer 4, an InGaN/GaN superlattice layer 5, an active layer 6, an undoped GaN-based layer 7, and a p-type GaN-based contact layer 8 are stacked on a sapphire substrate 1. A p-electrode 9 is formed on the p-type GaN-based contact layer 8. An n-electrode 10 is formed on a surface where the n-type GaN contact layer 4 is exposed as a result of mesa-etching. An intermediate semiconductor layer is formed between a well layer closest to a p-side in the active layer having a quantum well structure and the p-type GaN-based contact layer 8.
    Type: Application
    Filed: May 26, 2006
    Publication date: July 16, 2009
    Applicant: ROHM CO., LTD.
    Inventors: Ken Nakahara, Norikazu Ito, Kazuaki Tsutsumi
  • Publication number: 20090175306
    Abstract: Provided is a high-power red semiconductor laser having a laser element in which a temperature rise is suppressed with improved heat dissipation characteristics thereof, and which accordingly needs not be enlarged in heat dissipation area. An n-AlGaInP cladding layer, an AlGaInP optical guide layer, an MQW active layer, an AlGaInP optical guide layer, a p-AlGaInP first cladding layer, an AlGaInP etching stop layer, an n-AlGaInP block layer, a p-AlGaAs second cladding layer, a p-GaAs contact layer and a p-electrode are stacked on the top surface of a tilted n-GaAs substrate. An n-electrode is formed on the back surface of the n-GaAs substrate. The heat dissipation characteristics of the laser element are improved, because the second cladding layer contains AlGaAs, which has a higher heat conductivity.
    Type: Application
    Filed: August 9, 2006
    Publication date: July 9, 2009
    Applicant: ROHM Co., Ltd.
    Inventors: Ken Nakahara, Tsutomu Ishikawa
  • Publication number: 20090166607
    Abstract: Provided is a nitride semiconductor light emitting element having an improved carrier injection efficiency from a p-type nitride semiconductor layer to an active layer by simple means from a viewpoint utterly different from the prior art. A buffer layer 2, an undoped GaN layer 3, an n-type GaN contact layer 4, an InGaN/GaN superlattice layer 5, an active layer 6, a first undoped InGaN layer 7, a second undoped InGaN layer 8, and a p-type Gan-based contact layer 9 are stacked on a sapphire substrate 1. A p-electrode 10 is formed on the p-type Gan-based contact layer 9. An n-electrode 11 is formed on a surface where the n-type GaN contact layer 4 is exposed as a result of mesa-etching. The first undoped InGaN layer 7 is formed to contact a well layer closest to a p-side in the active layer having a quantum well structure, and subsequently the second undoped InGaN layer 8 is formed thereon.
    Type: Application
    Filed: May 26, 2006
    Publication date: July 2, 2009
    Applicant: ROHM CO., LTD.
    Inventors: Ken Nakahara, Norikazu Ito, Kazuaki Tsutsumi
  • Publication number: 20090146160
    Abstract: Provided is a gallium nitride semiconductor light emitting element capable of stabilizing a drive voltage by reducing carrier depletion attributable to spontaneous polarization and piezo polarization generated at the interface between an AlGaN semiconductor layer and a GaN semiconductor layer. A gallium nitride semiconductor crystal 2 including a light emitting region is formed on the R plane of a sapphire substrate 1. In addition, in another constitution, a gallium nitride semiconductor crystal 2 is formed on the A plane of a GaN substrate 3 or on the M plane of a GaN substrate 4. The growth surface of these gallium nitride semiconductor crystals 2 are not an N (nitrogen) polar face or a Ga polar face but are non-polar faces. This can decrease the strength of an electric field caused by spontaneous polarization and piezo polarization generated at the interface of GaN/AlGaN at the p side. Thus, carrier depletion can be avoided.
    Type: Application
    Filed: November 29, 2006
    Publication date: June 11, 2009
    Inventor: Ken Nakahara
  • Publication number: 20090146541
    Abstract: Provided is an infrared reflector having the configuration in which a dielectric film, an Au (gold) film, and an oxide film are sequentially formed on a substrate. The infrared reflector with this configuration is used so that the oxide film would face a body to be heated. In addition, infrared light emitted from a heat source can be reflected and collected by a reflection metal of the Au film to the body to be heated. Moreover, since the dielectric film is formed on the substrate, it is possible to prevent Au from dispersing under high temperature and thus to prevent deterioration of the infrared reflector.
    Type: Application
    Filed: March 7, 2008
    Publication date: June 11, 2009
    Applicant: ROHM CO., LTD.
    Inventors: Ken Nakahara, Hiroyuki Yuji, Kentaro Tamura, Shunsuke Akasaka, Masashi Kawasaki, Akira Ohtomo, Atsushi Tsukazaki
  • Publication number: 20090127570
    Abstract: Provided are a double wavelength semiconductor light emitting device, having an n electrode and p electrode disposed on the same surface side, in which the area of a chip is reduced to increase the number of chips taken from one single wafer, in which light focusing performance of double wavelength optical beams are improved, and in which an active layer of a light emitting element having a longer wavelength can be prevented from deteriorating in a process of manufacturing; and a method of manufacturing the same. Semiconductor lasers D1 and D2 as two light emitting elements having different wavelengths are integrally formed on a common substrate 1. A semiconductor laminate A is deposited on an n-type contact layer 21 in a semiconductor laser D1, and a semiconductor laminate B is deposited in a semiconductor laser D2. The semiconductor laminate A and semiconductor laminate B are configured to have different layer structures.
    Type: Application
    Filed: February 23, 2007
    Publication date: May 21, 2009
    Inventors: Shinichi Tamai, Ken Nakahara, Atsushi Yamaguchi
  • Publication number: 20090097521
    Abstract: A side surface light emitting semiconductor element includes: an AlGaN layer doped with Mg at a concentration equal to or less than 5×1019 cm?3; a ridge having a striped shape and formed in an upper portion of a laminated structure which includes the AlGaN layer and an active layer; and a Schottky barrier formed on a top surface of the laminated structure in an area where the ridge is not formed and the AlGaN layer is exposed.
    Type: Application
    Filed: March 15, 2007
    Publication date: April 16, 2009
    Applicant: ROHM CO., LTD.
    Inventor: Ken Nakahara
  • Publication number: 20090078934
    Abstract: There is provided a semiconductor light emitting device in which light emitting efficiency is totally improved in case of emitting a light having a short wavelength of 400 nm or less by raising internal quantum efficiency by enhancing crystallinity of semiconductor layers laminated and by raising external quantum efficiency by taking out the light emitted by preventing the light emitted from being absorbed in the substrate or the like, as much as possible. In case of laminating ZnO compound semiconductor layers (2 to 6) so as to form a light emitting layer forming portion (7) for emitting the light having a wavelength of 400 nm or less on a substrate (1), a substrate composed of MgxZn1-xO (0?x?0.5) is used as the substrate (1).
    Type: Application
    Filed: March 23, 2006
    Publication date: March 26, 2009
    Applicant: Rohm Co., Ltd.
    Inventor: Ken Nakahara
  • Publication number: 20090068779
    Abstract: There is provided a method for manufacturing a nitride semiconductor device which has a p-type nitride semiconductor layer having a high carrier concentration (low resistance) by activating an acceptor without raising a problem of forming nitrogen vacancies which are generated when a high temperature annealing is carried out over an extended time. A semiconductor lamination portion (6) made of nitride semiconductor is formed on a substrate (1) so as to form a light emitting layer, and irradiated by a laser beam having a wavelength ? of ?=h*c/E or less (E is energy capable of separating off the bonding between Mg and H) from the front surface side of the semiconductor lamination portion. Then, a heat treatment is carried out at a temperature of 300 to 400° C.
    Type: Application
    Filed: May 8, 2006
    Publication date: March 12, 2009
    Applicant: Rohm Co., Ltd.
    Inventor: Ken Nakahara
  • Publication number: 20090057695
    Abstract: A nitride semiconductor device according to the present invention sequentially includes at least an n-electrode, an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. The n-type semiconductor layer includes: an n-type GaN contact layer including n-type impurity-doped GaN having an electron concentration ranging from 5×1016 cm?3 to 5×1018 cm?3; the n-electrode provided on one of a main surface of the n-type GaN contact layer; and a generating layer provided on other main surface of the n-type GaN contact layer, including at least any one of AlxGa1-xN (0<x<1) and InxGa1-xN (0<x<1), and generates an electron accumulation layer for accumulating layer electrons at a boundary surface with the n-type GaN contact layer.
    Type: Application
    Filed: February 8, 2007
    Publication date: March 5, 2009
    Applicant: ROHM CO., LTD
    Inventor: Ken Nakahara
  • Publication number: 20090045393
    Abstract: 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: Application
    Filed: May 8, 2006
    Publication date: February 19, 2009
    Applicant: Rohm Co., Ltd.
    Inventor: Ken Nakahara