Patents by Inventor Kengo Nagata

Kengo Nagata 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: 20180019374
    Abstract: There is provided a Group III nitride semiconductor light-emitting device exhibiting improved crystallinity while suppressing abnormal growth of semiconductor layer due to pits and a production method therefor. In forming an n-side electrostatic breakdown preventing layer, pits are generated from the n-side electrostatic breakdown preventing layer. In forming an n-side superlattice layer, the layer is formed by alternately depositing a first InGaN layer and a GaN layer having an In composition ratio lower than that of the first InGaN layer, so that the In composition ratio and the total thickness of the first InGaN layers satisfy the following equation: 0<Y 180X+22, 0<X 0.1, X: In composition ratio of InGaN layers, and Y: Total thickness of InGaN layers (nm).
    Type: Application
    Filed: July 5, 2017
    Publication date: January 18, 2018
    Inventors: Kengo NAGATA, Taiji Yamamoto
  • Publication number: 20170373218
    Abstract: The present techniques provide a method for producing a Group III nitride semiconductor light-emitting device, which method is intended to grow semiconductor layers with high crystallinity on a sapphire substrate having a small area ratio of a base surface to a main surface. In preparing a substrate, a substrate is prepared, of which a main surface has a c-plane base surface and a plurality of projections protruding from the base surface, and the area ratio of the base surface to the main surface is 8% to 32%. In preparing an AlN buffer layer, the AlN buffer layer having a thickness of 34 nm to 14 nm is formed through MOCVD. The thickness of the AlN buffer layer is decreased as the area ratio of the base surface to the main surface of the substrate is increased.
    Type: Application
    Filed: June 13, 2017
    Publication date: December 28, 2017
    Inventor: Kengo NAGATA
  • Publication number: 20170213936
    Abstract: The present invention provides a Group III nitride semiconductor light-emitting device in which electrons and holes are suppressed from being captured by threading dislocation, and a production method therefor. The light-emitting device comprises an n-type contact layer, an n-side electrostatic breakdown preventing layer, an n-side superlattice layer, a light-emitting layer, a p-type cladding layer, a p-type contact layer, a transparent electrode, an n-electrode, and a p-electrode. The light-emitting device has a plurality of pits extending from the n-type semiconductor layer to the p-type semiconductor layer. The n-side electrostatic breakdown preventing layer has an n-type AlGaN layer. The n-type AlGaN layer includes starting points of the pits.
    Type: Application
    Filed: January 18, 2017
    Publication date: July 27, 2017
    Inventor: Kengo NAGATA
  • Patent number: 9601654
    Abstract: To provide a Group III nitride semiconductor light-emitting device production method, which is intended to grow a flat light-emitting layer without reducing the In concentration of the light-emitting layer. The method of the techniques includes an n-side superlattice layer formation step, in which an InGaN layer, a GaN layer disposed on the InGaN layer, and an n-type GaN layer disposed on the GaN layer are repeatedly formed. In formation of the InGaN layer, nitrogen gas is supplied as a carrier gas. In formation of the n-type GaN layer, a first mixed gas formed of nitrogen gas and hydrogen gas is supplied as a carrier gas. The first mixed gas has a hydrogen gas ratio by volume greater than 0% to 75% or less.
    Type: Grant
    Filed: October 24, 2015
    Date of Patent: March 21, 2017
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Kengo Nagata, Ryo Nakamura
  • Patent number: 9570656
    Abstract: The present invention provides a Group III nitride semiconductor light-emitting device having a flat semiconductor layer, in which the stress applied to the light-emitting layer is relaxed. The light-emitting layer of the light-emitting device includes a well layer and a barrier layer comprising an AlGaN layer containing In. The light-emitting device has a pit extending from an n-type semiconductor layer to layers above the light-emitting layer. A pit diameter at an interface between the light-emitting layer and the n-type semiconductor layer is 120 nm to 200 nm. The barrier layer has an In concentration of 6.0×1019 cm?3.
    Type: Grant
    Filed: September 12, 2014
    Date of Patent: February 14, 2017
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Kengo Nagata, Ryo Nakamura
  • Patent number: 9564552
    Abstract: The present invention provides a Group III nitride semiconductor light-emitting device exhibiting improved emission performance. In a MQW structure light-emitting layer in which a plurality of layer units is repeatedly deposited, each layer unit comprising an InGaN well layer, a GaN protective layer, and an AlGaN barrier layer sequentially deposited, the protective layer is formed as follows. The protective layer is grown at the same temperature as employed for the well layer. The growth rate of the protective layer is larger than 0.5 times and not larger than 1.1 times the growth rate of the well layer. The protective layer is formed so as to have a thickness of 5 ? to 8 ? at the start of growth of the barrier layer being formed thereafter.
    Type: Grant
    Filed: January 27, 2015
    Date of Patent: February 7, 2017
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Ryo Nakamura, Kengo Nagata
  • Publication number: 20160293792
    Abstract: The present invention provides a Group III nitride semiconductor light-emitting device exhibiting improved emission performance. In a MQW structure light-emitting layer in which a plurality of layer units is repeatedly deposited, each layer unit comprising an InGaN well layer, a GaN protective layer, and an AlGaN barrier layer sequentially deposited, the protective layer is formed as follows. The protective layer is grown at the same temperature as employed for the well layer. The growth rate of the protective layer is larger than 0.5 times and not larger than 1.1 times the growth rate of the well layer. The protective layer is formed so as to have a thickness of 5 ? to 8 ? at the start of growth of the barrier layer being formed thereafter.
    Type: Application
    Filed: January 27, 2015
    Publication date: October 6, 2016
    Inventors: Ryo NAKAMURA, Kengo Nagata
  • Publication number: 20160133783
    Abstract: To provide a Group III nitride semiconductor light-emitting device production method, which is intended to grow a flat light-emitting layer without reducing the In concentration of the light-emitting layer. The method of the techniques includes an n-side superlattice layer formation step, in which an InGaN layer, a GaN layer disposed on the InGaN layer, and an n-type GaN layer disposed on the GaN layer are repeatedly formed. In formation of the InGaN layer, nitrogen gas is supplied as a carrier gas. In formation of the n-type GaN layer, a first mixed gas formed of nitrogen gas and hydrogen gas is supplied as a carrier gas. The first mixed gas has a hydrogen gas ratio by volume greater than 0% to 75% or less.
    Type: Application
    Filed: October 24, 2015
    Publication date: May 12, 2016
    Inventors: Kengo NAGATA, Ryo Nakamura
  • Publication number: 20150083993
    Abstract: The present invention provides a Group III nitride semiconductor light-emitting device having a flat semiconductor layer, in which the stress applied to the light-emitting layer is relaxed. The light-emitting layer of the light-emitting device includes a well layer and a barrier layer comprising an AlGaN layer containing In. The light-emitting device has a pit extending from an n-type semiconductor layer to layers above the light-emitting layer. A pit diameter at an interface between the light-emitting layer and the n-type semiconductor layer is 120 nm to 200 nm. The barrier layer has an In concentration of 6.0×1019 cm?3.
    Type: Application
    Filed: September 12, 2014
    Publication date: March 26, 2015
    Inventors: Kengo NAGATA, Ryo NAKAMURA
  • Patent number: 8989219
    Abstract: When a transmission rate of each of lines that transmit data simultaneously between two STAs by using a plurality of radio channels and/or MIMO can be set independently, one data frame is fragmented in accordance with the transmission rates of the respective lines so as to generate a plurality of data packets having the same packet time length and data sizes equal to or smaller than a maximum data size. Those data packets are transmitted simultaneously by using a plurality of radio channels, or one radio channel and MIMO, or a plurality of radio channels and MIMO.
    Type: Grant
    Filed: April 18, 2011
    Date of Patent: March 24, 2015
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Akinori Hirukawa, Atsushi Ohta
  • Patent number: 8989108
    Abstract: In retransmission processing due to a failure of transmission of data packets, a plurality of data packets are simultaneously transmitted between two STAs by utilizing multiple wireless channels and MIMO, and the number of idle channels and the number of retransmission packets are compared. Then, when both of the numbers are different or only when the number of idle channels is larger than the number of retransmission packets, the retransmission packets are reconstructed according to the number of idle channels, and the reconstructed retransmission packets are simultaneously transmitted by using the idle channels.
    Type: Grant
    Filed: May 16, 2011
    Date of Patent: March 24, 2015
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Atsushi Ohta, Akinori Hirukawa
  • Patent number: 8369789
    Abstract: An interference cancelling station ICS includes a transmission weight factor calculating unit calculating a transmission weight factor w2 and an interference cancelling data signal transmitting unit generating an interference cancelling data signal by multiplying, by the transmission weight factor w2, a data signal transmitted by a base station BSb of the wireless communication system B and transmitting the interference cancelling data signal in synchronization with timing with which the base station BSb of a wireless communication system B transmits the data signal, and a mobile station MSa of a wireless communication system A receives a data signal transmitted by a base station BSa of the wireless communication system A, the data signal having cancelled interference from the base station BSb of the wireless communication system B.
    Type: Grant
    Filed: February 5, 2009
    Date of Patent: February 5, 2013
    Assignee: Nippon Telegraph and Telphone Corporation
    Inventors: Jun Mashino, Takatoshi Sugiyama, Kentaro Nishimori, Kengo Nagata, Yusuke Asai
  • Patent number: 8284746
    Abstract: A wireless relay device connecting a wireless terminal to one of a plurality of access networks with different wireless interfaces and performing relay processing between the wireless terminal and one of the plurality of access networks being connected, the wireless relay device including a wireless interface on local side to be connected to the wireless terminal, a plurality of wireless interfaces on network side to be connected to the plurality of respective access networks, and a connection control section which boots the plurality of wireless interfaces on network side when the wireless interface on local side receives a signal from the wireless terminal, connects a wireless interface on network side establishing a fastest connection and the wireless interface on local side, and connects the wireless terminal to an access network corresponding to the wireless interface on network side establishing the fastest connection.
    Type: Grant
    Filed: August 28, 2008
    Date of Patent: October 9, 2012
    Assignees: Nippon Telegraph and Telephone Corporation, NTT Broadband Platform, Inc.
    Inventors: Tomohiro Tokuyasu, Makoto Umeuchi, Toshihiro Manabe, Hiroshi Hojo, Kengo Nagata, Tadao Kobayashi
  • Publication number: 20110216728
    Abstract: In retransmission processing due to a failure of transmission of data packets, a plurality of data packets are simultaneously transmitted between two STAs by utilizing multiple wireless channels and MIMO, and the number of idle channels and the number of retransmission packets are compared. Then, when both of the numbers are different or only when the number of idle channels is larger than the number of retransmission packets, the retransmission packets are reconstructed according to the number of idle channels, and the reconstructed retransmission packets are simultaneously transmitted by using the idle channels.
    Type: Application
    Filed: May 16, 2011
    Publication date: September 8, 2011
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Atsushi Ohta, Akinori Hirukawa
  • Publication number: 20110194517
    Abstract: When a transmission rate of each of lines that transmit data simultaneously between two STAs by using a plurality of radio channels and/or MIMO can be set independently, one data frame is fragmented in accordance with the transmission rates of the respective lines so as to generate a plurality of data packets having the same packet time length and data sizes equal to or smaller than a maximum data size. Those data packets are transmitted simultaneously by using a plurality of radio channels, or one radio channel and MIMO, or a plurality of radio channels and MIMO.
    Type: Application
    Filed: April 18, 2011
    Publication date: August 11, 2011
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Akinori Hirukawa, Atsushi Ohta
  • Patent number: 7974243
    Abstract: In retransmission processing due to a failure of transmission of data packets, a plurality of data packets are simultaneously transmitted between two STAs by utilizing multiple wireless channels and MIMO, and the number of idle channels and the number of retransmission packets are compared. Then, when both of the numbers are different or only when the number of idle channels is larger than the number of retransmission packets, the retransmission packets are reconstructed according to the number of idle channels, and the reconstructed retransmission packets are simultaneously transmitted by using the idle channels.
    Type: Grant
    Filed: June 18, 2004
    Date of Patent: July 5, 2011
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Atsushi Ohta, Akinori Hirukawa
  • Publication number: 20100291877
    Abstract: An interference cancelling station ICS includes a transmission weight factor calculating unit calculating a transmission weight factor w2 and an interference cancelling data signal transmitting unit generating an interference cancelling data signal by multiplying, by the transmission weight factor w2, a data signal transmitted by a base station BSb of the wireless communication system B and transmitting the interference cancelling data signal in synchronization with timing with which the base station BSb of a wireless communication system B transmits the data signal, and a mobile station MSa of a wireless communication system A receives a data signal transmitted by a base station BSa of the wireless communication system A, the data signal having cancelled interference from the base station BSb of the wireless communication system B.
    Type: Application
    Filed: February 5, 2009
    Publication date: November 18, 2010
    Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
    Inventors: Jun Mashino, Takatoshi Sugiyama, Kentaro Nishimori, Kengo Nagata, Yusuke Asai
  • Patent number: 7813317
    Abstract: Data packets are transmitted between two STAs capable of using plural radio channels and MIMO together, by using idle channels and MIMO. When at least one idle channel has been detected, plural data packets are generated in the same number as the sum of MIMO numbers of the respective idle channels, in which the data packets are generated from one or plural data frames, and plural data packets having the same packet time length are transmitted simultaneously between the two STAs by using the idle channels and MIMO.
    Type: Grant
    Filed: June 18, 2004
    Date of Patent: October 12, 2010
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Atsushi Ohta, Akinori Hirukawa, Yasuhiko Inoue
  • Patent number: 7760686
    Abstract: A plurality of types of available transmission rates to be used for transmission of data packets are individually managed for each receiver terminal. When there are a plurality of data packets to be transmitted onto a transmission buffer and when it is possible to transmit said plurality of data packets simultaneously, the packet sizes representative of the data amounts of the respective data packets are referred to as well as the transmission rates of the respective data packets associated with the receiver terminals. The packet time lengths (transmission times) defined by the packet sizes and transmission rates are checked for the respective data packets. A plurality of data packets whose packet time lengths are approximately equal to each other are selected regardless of their receiver terminals. The transmissions of the plurality of selected data packets are commenced simultaneously by use of a plurality of radio channels.
    Type: Grant
    Filed: September 9, 2004
    Date of Patent: July 20, 2010
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventors: Kazuyoshi Saito, Tomoaki Kumagai, Shinya Otsuki, Kengo Nagata, Satoru Aikawa
  • Publication number: 20100172285
    Abstract: A wireless relay device connecting a wireless terminal to one of a plurality of access networks with different wireless interfaces and performing relay processing between the wireless terminal and one of the plurality of access networks being connected, the wireless relay device including a wireless interface on local side to be connected to the wireless terminal, a plurality of wireless interfaces on network side to be connected to the plurality of respective access networks, and a connection control section which boots the plurality of wireless interfaces on network side when the wireless interface on local side receives a signal from the wireless terminal, connects a wireless interface on network side establishing a fastest connection and the wireless interface on local side, and connects the wireless terminal to an access network corresponding to the wireless interface on network side establishing the fastest connection.
    Type: Application
    Filed: August 28, 2008
    Publication date: July 8, 2010
    Applicants: NIPPON TELEGRAPH AND TELEPHONE CORPORATION, NTT BROADFORM PLATFORM, INC.
    Inventors: Tomohiro Tokuyasu, Makoto Umeuchi, Toshihiro Manabe, Hiroshi Hojo, Kengo Nagata, Tadao Kobayashi