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).

  • Patent number: 8410478
    Abstract: A p-type MgxZn1-xO-based thin film (1) is formed on a substrate (2) made of a ZnO-based semiconductor. The p-type MgxZn1-xO-based thin film (1) is composed so that X as a ratio of Mg with respect to Zn therein can be 0?X<1, preferably 0?X?0.5. In the p-type MgZnO thin film (1), nitrogen as p-type impurities which become an acceptor is contained at a concentration of approximately 5.0×1018 cm?3 or more. The p-type MgZnO thin film (1) is composed so that n-type impurities made of a group IV element such as silicon that becomes a donor can have a concentration of approximately 1.0×1017 cm?3 or less. The p-type MgZnO thin film (1) is composed so that n-type impurities made of a group III element such as boron and aluminum which become a donor can have a concentration of approximately 1.0×1016 cm?3 or less.
    Type: Grant
    Filed: August 1, 2008
    Date of Patent: April 2, 2013
    Assignee: Rohm Co., Ltd.
    Inventors: Ken Nakahara, Hiroyuki Yuji, Kentaro Tamura, Shunsuke Akasaka, Masashi Kawasaki, Akira Ohtomo, Atsushi Tsukazaki
  • Patent number: 8304795
    Abstract: 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. A p-side electrode (8) is provided on the light transmitting conductive layer, and an n-side electrode (9) is electrically connected to the n-type layer exposed by etching a part of the semiconductor lamination portion. Light emitted from the light emitting layer is therefore totally reflected repeatedly in the semiconductor lamination portion and the substrate and can be effectively taken out without attenuation, so external quantum efficiency can be improved.
    Type: Grant
    Filed: December 28, 2006
    Date of Patent: November 6, 2012
    Assignee: Rohm Co., Ltd.
    Inventors: Atsushi Yamaguchi, Ken Nakahara
  • Publication number: 20120213242
    Abstract: A semiconductor laser device includes a nitride semiconductor laminate structure including an n-type clad layer, an n-type guide layer formed on the n-type clad layer, a light emitting layer formed on the n-type guide layer and a p-type semiconductor layer formed on the light emitting layer. The nitride semiconductor laminate structure does not include a p-type semiconductor clad layer. The semiconductor laser device further includes an upper clad layer formed on the p-type semiconductor layer. The upper clad layer includes a first conductive film made of an indium oxide-based material and a second conductive film formed on the first conductive film and made of a zinc oxide-based material, a gallium oxide-based material or a tin oxide-based material.
    Type: Application
    Filed: February 16, 2012
    Publication date: August 23, 2012
    Applicant: ROHM CO., LTD.
    Inventors: Taketoshi Tanaka, Shinya Takado, Junichi Kashiwagi, Masashi Yamamoto, Ken Nakahara
  • Patent number: 8247793
    Abstract: Provided are a ZnO-based thin film and a ZnO-based semiconductor device which allow: reduction in a burden on a manufacturing apparatus; improvement of controllability and reproducibility of doping; and obtaining p-type conduction without changing a crystalline structure. In order to be formed into a p-type ZnO-based thin film, a ZnO-based thin film is formed by employing as a basic structure a superlattice structure of a MgZnO/ZnO super lattice layer 3. This superlattice component is formed with a laminated structure which includes acceptor-doped MgZnO layers 3b and acceptor-doped ZnO layers 3a. Hence, it is possible to improve controllability and reproducibility of the doping, and to prevent a change in a crystalline structure due to a doping material.
    Type: Grant
    Filed: June 13, 2008
    Date of Patent: August 21, 2012
    Assignee: Rohm Co., Ltd.
    Inventors: Ken Nakahara, Shunsuke Akasaka, Masashi Kawasaki, Akira Ohtomo, Atsushi Tsukazaki
  • Publication number: 20120199826
    Abstract: Two light receiving elements are formed on a support substrate. A first light receiving element is formed of a p-type layer, an n-type layer, a light absorption semiconductor layer, an anode electrode, a cathode electrode, a protection film, etc. A second light receiving element is formed of a p-type layer, an n-type layer, a transmissive film, an anode electrode, a cathode electrode, a protection film, etc. The light absorption semiconductor layer absorbs light in a wavelength range ? and disposed closer to the light receiving surface than is the pn junction region. The transmissive film has no light absorption range and disposed closer to the light receiving surface than is the pn junction region. The amount of light in the wavelength range ? is measured through computation using a detection signal from the first light receiving element and a detection signal from the second light receiving element.
    Type: Application
    Filed: October 14, 2011
    Publication date: August 9, 2012
    Applicant: ROHM CO., LTD.
    Inventors: Ken NAKAHARA, Shunsuke AKASAKA, Koki SAKAMOTO, Tetsuo FUJII, Shunsuke FURUSE, Soichiro ARIMURA
  • Publication number: 20120181531
    Abstract: A semiconductor element includes a semiconductor layer mainly composed of MgxZn1-xO (0<=x<1), in which manganese contained in the semiconductor layer as impurities has a density of not more than 1×1016 cm?3.
    Type: Application
    Filed: August 7, 2008
    Publication date: July 19, 2012
    Applicant: ROHM CO., LTD
    Inventors: Ken Nakahara, Shunsuke Akasaka, Masashi Kawasaki, Akira Ohtomo, Atsushi Tsukazaki
  • Patent number: 8154036
    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: Grant
    Filed: February 8, 2007
    Date of Patent: April 10, 2012
    Assignee: Rohm Co., Ltd.
    Inventor: Ken Nakahara
  • Publication number: 20120064653
    Abstract: A method for manufacturing a nitride semiconductor device such as a nitride semiconductor light emitting device, a transistor device or the like. The method includes the steps of forming a buffer crystalline layer of the nitride semiconductor made of AlxGayIn1-x-yN (0?x?1, 0?y ?1 and 0?x+y?1), in which both an a-axis and a c-axis are aligned, directly on a substrate lattice-mismatched with the nitride semiconductor without forming an amorphous low temperature buffer layer, by plasma laser deposition(PLD) method, and growing epitaxially the nitride semiconductor layer on the buffer layer so as to form a device such as a nitride semiconductor light emitting diode, by metal organic chemical vapor deposition (MOCVD).
    Type: Application
    Filed: September 24, 2011
    Publication date: March 15, 2012
    Applicant: ROHM CO., LTD.
    Inventors: Ken NAKAHARA, Kentaro Tamura
  • Patent number: 8124985
    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: Grant
    Filed: February 7, 2006
    Date of Patent: February 28, 2012
    Assignee: Rohm Co., Ltd.
    Inventors: Mitsuhiko Sakai, Atsushi Yamaguchi, Ken Nakahara, Masayuki Sonobe, Tsuyoshi Tsutsui
  • Publication number: 20120022382
    Abstract: A wireless plethysmogram sensor unit is capable of obtaining a plethysmogram from a living tissue of a measuring object and of transmitting the plethysmogram to a processing unit outside the wireless plethysmogram sensor unit. The sensor unit includes a light source to emit measuring light into the living tissue and a light receiving element to receive light emerging from the tissue, which is accompanied by pulsation caused by absorption by arteries in the tissue. A memory stores a plethysmogram obtained in accordance with the light received by the light receiving element. A short range wireless communicator transmits the plethysmogram to the processing unit. A power source provides power to other elements in the sensor unit, and a controller controls the elements of the sensor unit.
    Type: Application
    Filed: July 11, 2011
    Publication date: January 26, 2012
    Applicant: ROHM CO., LTD.
    Inventors: Niwa Daisuke, Koji Terumoto, Kazuhiro Oguchi, Masahide Tanaka, Ken Nakahara
  • Patent number: 8053756
    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: Grant
    Filed: May 26, 2006
    Date of Patent: November 8, 2011
    Assignee: Rohm Co., Ltd.
    Inventors: Ken Nakahara, Norikazu Ito, Kazuaki Tsutsumi
  • Patent number: 8049235
    Abstract: Provided is a nitride semiconductor light emitting element that has improved light extraction efficiency and a wide irradiation angle of outgoing light irrespective of the reflectance of a metal used for an electrode. An n side anti-reflection layer 2 and a p side Bragg reflection layer 4 are formed so as to sandwich an MQW active layer 3 that serves as a light emitting region, and the nitride semiconductor light emitting element has a double hetero structure. On top of the n side anti-reflection layer 2, an n electrode 1 is formed. Meanwhile, at the lower side of the p side Bragg reflection layer 4, a p electrode 5, a reflection film 7, and a pad electrode 8 are formed, and the pad electrode is bonded to a support substrate 10 with a conductive bonding layer 9 interposed in between. Both the n side anti-reflection layer 2 and the p side Bragg reflection layer 4 also serve as contact layers.
    Type: Grant
    Filed: January 23, 2007
    Date of Patent: November 1, 2011
    Assignee: Rohm Co., Ltd.
    Inventor: Ken Nakahara
  • Publication number: 20110204355
    Abstract: A zinc oxide based substrate satisfies a condition that impurities Si, C, Ge, Sn, and Pb which are Group IV elements each have a concentration of 1×1017 cm?3 or less. More preferably, the zinc oxide based substrate 2 satisfies a condition that impurities Li, Na, K, Rb, and Fr which are Group I elements each have a concentration of 1×1016 cm?3 or less. The impurity concentration of a zinc oxide based semiconductor grown on the zinc oxide based substrate can be reduced in this manner.
    Type: Application
    Filed: August 26, 2010
    Publication date: August 25, 2011
    Applicants: ROHM CO., LTD., MITSUBISHI CHEMICAL CORPORATION, TOKYO DENPA CO., LTD.
    Inventors: Takao SUZUKI, Ken NAKAHARA, Hiroyuki YUJI
  • Patent number: 8004006
    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: Grant
    Filed: November 7, 2006
    Date of Patent: August 23, 2011
    Assignee: Rohm Co., Ltd.
    Inventors: Ken Nakahara, Atsushi Yamaguchi
  • Publication number: 20110181765
    Abstract: A circuit unit is formed on a supporting member, and a solid state imaging element is formed on the circuit unit. Also, a lens mechanism is provided on a front surface of the solid state imaging element. The solid state imaging element, the circuit unit and the lens mechanism are mounted in a frame body. In addition, photoelectric conversion elements are attached to the outside of the frame body. Each of the photoelectric conversion elements is configured to have almost no light reception sensitivity to the light wavelength region of more than 300 nm and have sensitivity to the light wavelength region of 300 nm or less. The photoelectric conversion element thus configured can sense particularly flames, electric sparks and the like among ultraviolet light.
    Type: Application
    Filed: January 20, 2011
    Publication date: July 28, 2011
    Applicant: ROHM CO., LTD.
    Inventor: Ken NAKAHARA
  • Publication number: 20110180688
    Abstract: A photoelectric converter includes: a lower electrode layer; a compound semiconductor thin film of chalcopyrite structure disposed on the lower electrode layer and having a high-resistivity layer in its surface; a transparent electrode layer disposed on the compound semiconductor thin film; an interlayer insulating layer; a zinc-oxide-based compound semiconductor thin film; and electrodes. With application of a reverse bias voltage between the transparent electrode layer and the lower electrode layer, and application of a bias voltage between the electrodes, the photoelectric converter photoelectrically converts ultraviolet region light. Thus, the photoelectric converter achieves photoelectric conversion of light in a wider region. Such a photoelectric converter and a process for producing the same, and a solid state imaging device to which the photoelectric converter is applied are provided.
    Type: Application
    Filed: January 20, 2011
    Publication date: July 28, 2011
    Applicant: ROHM CO., LTD.
    Inventor: Ken Nakahara
  • Patent number: 7960727
    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: Grant
    Filed: September 21, 2006
    Date of Patent: June 14, 2011
    Assignee: Rohm Co., Ltd.
    Inventors: Ken Nakahara, Yuji Hiroyuki
  • Publication number: 20110133208
    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?×(1?sin ?z)).
    Type: Application
    Filed: February 1, 2011
    Publication date: June 9, 2011
    Applicant: ROHM CO., LTD.
    Inventor: Ken Nakahara
  • Patent number: 7948003
    Abstract: 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: Grant
    Filed: July 21, 2008
    Date of Patent: May 24, 2011
    Assignee: Rohm Co., Ltd.
    Inventor: Ken Nakahara
  • Publication number: 20110114937
    Abstract: Provided are: a p-type MgZnO-based thin film that functions as a p-type; and a semiconductor light emitting device that includes the p-type MgZnO-based thin film. A p-type MgxZn1-xO-based thin film (1) is formed on a substrate (2) made of a ZnO-based semiconductor. The p-type MgxZn1-xO-based thin film (1) is composed so that X as a ratio of Mg with respect to Zn therein can be 0?X<1, preferably 0?X?0.5. In the p-type MgZnO thin film (1), nitrogen as p-type impurities which become an acceptor is contained at a concentration of approximately 5.0×1018 cm?3 or more. The p-type MgZnO thin film (1) is composed so that n-type impurities made of a group IV element such as silicon that becomes a donor can have a concentration of approximately 1.0×1017 cm?3 or less. The p-type MgZnO thin film (1) is composed so that n-type impurities made of a group III element such as boron and aluminum which become a donor can have a concentration of approximately 1.0×1016 cm?3 or less.
    Type: Application
    Filed: August 1, 2008
    Publication date: May 19, 2011
    Applicant: ROHM CO., LTD.
    Inventors: Ken Nakahara, Hiroyuki Yuji, Kentaro Tamura, Shunsuke Akasaka, Masashi Kawasaki, Akira Ohtomo, Atsushi Tsukazaki