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).
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Publication number: 20180019374Abstract: 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: ApplicationFiled: July 5, 2017Publication date: January 18, 2018Inventors: Kengo NAGATA, Taiji Yamamoto
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Publication number: 20170373218Abstract: 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: ApplicationFiled: June 13, 2017Publication date: December 28, 2017Inventor: Kengo NAGATA
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Publication number: 20170213936Abstract: 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: ApplicationFiled: January 18, 2017Publication date: July 27, 2017Inventor: Kengo NAGATA
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Patent number: 9601654Abstract: 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: GrantFiled: October 24, 2015Date of Patent: March 21, 2017Assignee: TOYODA GOSEI CO., LTD.Inventors: Kengo Nagata, Ryo Nakamura
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Patent number: 9570656Abstract: 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: GrantFiled: September 12, 2014Date of Patent: February 14, 2017Assignee: TOYODA GOSEI CO., LTD.Inventors: Kengo Nagata, Ryo Nakamura
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Patent number: 9564552Abstract: 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: GrantFiled: January 27, 2015Date of Patent: February 7, 2017Assignee: TOYODA GOSEI CO., LTD.Inventors: Ryo Nakamura, Kengo Nagata
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Publication number: 20160293792Abstract: 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: ApplicationFiled: January 27, 2015Publication date: October 6, 2016Inventors: Ryo NAKAMURA, Kengo Nagata
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Publication number: 20160133783Abstract: 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: ApplicationFiled: October 24, 2015Publication date: May 12, 2016Inventors: Kengo NAGATA, Ryo Nakamura
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Publication number: 20150083993Abstract: 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: ApplicationFiled: September 12, 2014Publication date: March 26, 2015Inventors: Kengo NAGATA, Ryo NAKAMURA
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Patent number: 8989219Abstract: 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: GrantFiled: April 18, 2011Date of Patent: March 24, 2015Assignee: Nippon Telegraph and Telephone CorporationInventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Akinori Hirukawa, Atsushi Ohta
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Patent number: 8989108Abstract: 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: GrantFiled: May 16, 2011Date of Patent: March 24, 2015Assignee: Nippon Telegraph and Telephone CorporationInventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Atsushi Ohta, Akinori Hirukawa
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Patent number: 8369789Abstract: 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: GrantFiled: February 5, 2009Date of Patent: February 5, 2013Assignee: Nippon Telegraph and Telphone CorporationInventors: Jun Mashino, Takatoshi Sugiyama, Kentaro Nishimori, Kengo Nagata, Yusuke Asai
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Patent number: 8284746Abstract: 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: GrantFiled: August 28, 2008Date of Patent: October 9, 2012Assignees: Nippon Telegraph and Telephone Corporation, NTT Broadband Platform, Inc.Inventors: Tomohiro Tokuyasu, Makoto Umeuchi, Toshihiro Manabe, Hiroshi Hojo, Kengo Nagata, Tadao Kobayashi
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Publication number: 20110216728Abstract: 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: ApplicationFiled: May 16, 2011Publication date: September 8, 2011Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Atsushi Ohta, Akinori Hirukawa
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Publication number: 20110194517Abstract: 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: ApplicationFiled: April 18, 2011Publication date: August 11, 2011Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Akinori Hirukawa, Atsushi Ohta
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Patent number: 7974243Abstract: 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: GrantFiled: June 18, 2004Date of Patent: July 5, 2011Assignee: Nippon Telegraph and Telephone CorporationInventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Atsushi Ohta, Akinori Hirukawa
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Publication number: 20100291877Abstract: 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: ApplicationFiled: February 5, 2009Publication date: November 18, 2010Applicant: NIPPON TELEGRAPH AND TELEPHONE CORPORATIONInventors: Jun Mashino, Takatoshi Sugiyama, Kentaro Nishimori, Kengo Nagata, Yusuke Asai
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Patent number: 7813317Abstract: 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: GrantFiled: June 18, 2004Date of Patent: October 12, 2010Assignee: Nippon Telegraph and Telephone CorporationInventors: Kengo Nagata, Tomoaki Kumagai, Shinya Otsuki, Kazuyoshi Saito, Satoru Aikawa, Atsushi Ohta, Akinori Hirukawa, Yasuhiko Inoue
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Patent number: 7760686Abstract: 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: GrantFiled: September 9, 2004Date of Patent: July 20, 2010Assignee: Nippon Telegraph and Telephone CorporationInventors: Kazuyoshi Saito, Tomoaki Kumagai, Shinya Otsuki, Kengo Nagata, Satoru Aikawa
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Publication number: 20100172285Abstract: 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: ApplicationFiled: August 28, 2008Publication date: July 8, 2010Applicants: NIPPON TELEGRAPH AND TELEPHONE CORPORATION, NTT BROADFORM PLATFORM, INC.Inventors: Tomohiro Tokuyasu, Makoto Umeuchi, Toshihiro Manabe, Hiroshi Hojo, Kengo Nagata, Tadao Kobayashi