Patents by Inventor Yasuhisa Ushida

Yasuhisa Ushida 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: 9318559
    Abstract: A semiconductor substrate includes a sapphire substrate including a c-plane main surface and a groove in a surface thereof, the groove including side surfaces and a bottom surface, and a Group III nitride semiconductor layer formed on the sapphire substrate. The side surfaces of the groove are an a-plane of sapphire. An axis of the Group III nitride semiconductor layer, perpendicular to one of the side surface of the groove, is a c-axis of Group III nitride semiconductor. A plane of the Group III nitride semiconductor, parallel to the main surface of the sapphire substrate, is an a-plane of Group III nitride semiconductor.
    Type: Grant
    Filed: September 28, 2015
    Date of Patent: April 19, 2016
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Naoyuki Nakada, Koji Okuno, Yasuhisa Ushida
  • Publication number: 20160020285
    Abstract: A semiconductor substrate includes a sapphire substrate including a c-plane main surface and a groove in a surface thereof, the groove including side surfaces and a bottom surface, and a Group III nitride semiconductor layer formed on the sapphire substrate. The side surfaces of the groove are an a-plane of sapphire. An axis of the Group III nitride semiconductor layer, perpendicular to one of the side surface of the groove, is a c-axis of Group III nitride semiconductor. A plane of the Group III nitride semiconductor, parallel to the main surface of the sapphire substrate, is an a-plane of Group III nitride semiconductor.
    Type: Application
    Filed: September 28, 2015
    Publication date: January 21, 2016
    Inventors: Naoyuki Nakada, Koji Okuno, Yasuhisa Ushida
  • Patent number: 9196687
    Abstract: A semiconductor substrate includes a sapphire substrate including an a-plane main surface and a groove in a surface thereof, the groove includes side surfaces and a bottom surface, and a Group III nitride semiconductor layer formed on the sapphire substrate. Both side surfaces of the groove assume a c-plane of sapphire. An axis perpendicular to one of the side surfaces of the groove of the Group III nitride semiconductor layer assumes a c-axis of Group III nitride semiconductor. A plane parallel to the main surface of the sapphire substrate of the Group III nitride semiconductor layer assumes an m-plane of Group III nitride semiconductor.
    Type: Grant
    Filed: February 19, 2014
    Date of Patent: November 24, 2015
    Assignee: TOYODA GOSEI CO., LTD.
    Inventors: Naoyuki Nakada, Koji Okuno, Yasuhisa Ushida
  • Patent number: 8980657
    Abstract: The present invention is a method for producing a light-emitting device whose p contact layer has a p-type conduction and a reduced contact resistance with an electrode. On a p cladding layer, by MOCVD, a first p contact layer of GaN doped with Mg is formed. Subsequently, after lowering the temperature to a growth temperature of a second p contact layer being formed in the subsequent process, which is 700° C., the supply of ammonia is stopped and the carrier gas is switched from hydrogen to nitrogen. Thereby, Mg is activated in the first p contact layer, and the first p contact layer has a p-type conduction. Next, the second p contact layer of InGaN doped with Mg is formed on the first p contact layer by MOCVD using nitrogen as a carrier gas while maintaining the temperature at 700° C. which is the temperature of the previous process.
    Type: Grant
    Filed: July 10, 2012
    Date of Patent: March 17, 2015
    Assignee: Toyoda Gosei Co., Ltd.
    Inventors: Shinya Boyama, Yasuhisa Ushida
  • Patent number: 8945965
    Abstract: The present invention provides a Group III nitride semiconductor light-emitting device exhibiting improved light extraction performance. In the production method, a p cladding layer of p-AlGaN is formed by the MOCVD method on a light-emitting layer at a pressure of 30 kPa and with an Mg concentration of 1.5×1020/cm3. A plurality of regions with a nitrogen polarity is formed in the crystals with a Group III element polarity, and thus the p cladding layer has a hexagonal columnar concave and convex configuration on the surface thereof. Subsequently, a p contact layer of GaN is formed by the MOCVD method, in a film along the concave and convex configuration on the p cladding layer.
    Type: Grant
    Filed: June 15, 2012
    Date of Patent: February 3, 2015
    Assignee: Toyoda Gosei Co., Ltd.
    Inventors: Naoyuki Nakada, Yasuhisa Ushida
  • Patent number: 8928001
    Abstract: A group III nitride compound semiconductor light emitting device that inhibits occurrence of dislocation in a strain relaxation layer in forming a group III nitride compound semiconductor layer on a thin GaN substrate, and a method for producing the same are provided. A light emitting device 100 comprises a support substrate 10, a GaN substrate 20, an n-type contact layer 30, a strain relaxation layer 40 (n-type InGaN layer), a light emitting layer 50, a p-type clad layer 60, and a p-type contact layer 70. The GaN substrate 20 has a thickness in a range of from 10 nm to 10 ?m. The strain relaxation layer 40 (n-type InGaN layer) has an In composition ratio X in a range of from larger than 0 to 3%.
    Type: Grant
    Filed: March 4, 2013
    Date of Patent: January 6, 2015
    Assignee: Toyoda Gosei Co., Ltd.
    Inventors: Yoshiki Saito, Yasuhisa Ushida, Masato Aoki
  • Publication number: 20140167222
    Abstract: A semiconductor substrate includes a sapphire substrate including an a-plane main surface and a groove in a surface thereof, the groove includes side surfaces and a bottom surface, and a Group III nitride semiconductor layer formed on the sapphire substrate. Both side surfaces of the groove assume a c-plane of sapphire. An axis perpendicular to one of the side surfaces of the groove of the Group III nitride semiconductor layer assumes a c-axis of Group III nitride semiconductor. A plane parallel to the main surface of the sapphire substrate of the Group III nitride semiconductor layer assumes an m-plane of Group III nitride semiconductor.
    Type: Application
    Filed: February 19, 2014
    Publication date: June 19, 2014
    Applicant: TOYODA GOSEI CO., LTD.
    Inventors: Naoyuki Nakada, Koji Okuno, Yasuhisa Ushida
  • Patent number: 8680581
    Abstract: The present invention provides a method for producing a Group III nitride semiconductor. The method includes forming a groove in a surface of a growth substrate through etching; forming a buffer film on the groove-formed surface of the growth substrate through sputtering; heating, in an atmosphere containing hydrogen and ammonia, the substrate to a temperature at which a Group III nitride semiconductor of interest is grown; and epitaxially growing the Group III nitride semiconductor on side surfaces of the groove at the growth temperature. The thickness of the buffer film or the growth temperature is regulated so that the Group III nitride semiconductor is grown primarily on the side surfaces of the groove in a direction parallel to the main surface of the growth substrate.
    Type: Grant
    Filed: December 23, 2009
    Date of Patent: March 25, 2014
    Assignee: Toyoda Gosei Co., Ltd.
    Inventors: Naoyuki Nakada, Koji Okuno, Yasuhisa Ushida
  • Publication number: 20130328097
    Abstract: A group III nitride semiconductor light-emitting element having a rectangular shape in a planar view, the element comprises an n-electrode connecting to an n-type layer and a p-electrode connecting to a p-type layer, on a same plane side; wherein the n-electrode has a n-wiring-shaped part that is wiring-shaped and extending along a first side of the rectangular shape; the p-electrode has a p-wiring-shaped part that is wiring-shaped and extending along the first side of the rectangular shape; when a distance that is between the n-wiring-shaped part and the p-wiring-shaped part is a, and a distance that is between the one side of the rectangular shape and at least one of the n-wiring-shaped part and the p-wiring-shaped part and that is nearest to the first side is b, the n-wiring-shaped part and the p-wiring-shaped part are arranged such that the distances a and b satisfy 1.65?a/b?7.00.
    Type: Application
    Filed: June 10, 2013
    Publication date: December 12, 2013
    Inventors: Naoyuki NAKADA, Yasuhisa Ushida
  • Patent number: 8598599
    Abstract: The present invention provides a Group III nitride semiconductor light-emitting device whose main surface is a plane which provides an internal electric field of zero, and which exhibits improved emission performance. The light-emitting device includes a sapphire substrate which has, in a surface thereof, a plurality of dents which are arranged in a stripe pattern as viewed from above; an n-contact layer formed on the dented surface of the sapphire substrate; a light-emitting layer formed on the n-contact layer; an electron blocking layer formed on the light-emitting layer; a p-contact layer formed on the electron blocking layer; a p-electrode; and an n-electrode. The electron blocking layer has a thickness of 2 to 8 nm and is formed of Mg-doped AlGaN having an Al compositional proportion of 20 to 30%.
    Type: Grant
    Filed: March 25, 2011
    Date of Patent: December 3, 2013
    Assignee: Toyoda Gosei Co., Ltd.
    Inventors: Yoshiki Saito, Koji Okuno, Yasuhisa Ushida
  • Publication number: 20130256687
    Abstract: A group III nitride compound semiconductor light emitting device that inhibits occurrence of dislocation in a strain relaxation layer in forming a group III nitride compound semiconductor layer on a thin GaN substrate, and a method for producing the same are provided. A light emitting device 100 comprises a support substrate 10, a GaN substrate 20, an n-type contact layer 30, a strain relaxation layer 40 (n-type InGaN layer), a light emitting layer 50, a p-type clad layer 60, and a p-type contact layer 70. The GaN substrate 20 has a thickness in a range of from 10 nm to 10 ?m. The strain relaxation layer 40 (n-type InGaN layer) has an In composition ratio X in a range of from larger than 0 to 3%.
    Type: Application
    Filed: March 4, 2013
    Publication date: October 3, 2013
    Applicant: TOYODA GOSEI CO., LTD.
    Inventors: Yoshiki SAITO, Yasuhisa USHIDA, Masato AOKI
  • Patent number: 8546836
    Abstract: A light-emitting element includes a semiconductor laminated structure including a nitride semiconductor, and formed by laminating a first semiconductor layer of a first conductivity type, a light-emitting layer and a second semiconductor layer of a second conductivity type different from the first conductivity type, the first semiconductor layer being exposed by removing a part of the second semiconductor layer and the light-emitting layer, a concave portion formed in the exposed portion of the first semiconductor layer, a first electrode formed on the concave portion and being in ohmic contact with the first semiconductor layer, and a second electrode being in ohmic contact with the second semiconductor layer and formed surrounding the first electrode.
    Type: Grant
    Filed: June 10, 2011
    Date of Patent: October 1, 2013
    Assignee: Toyoda Gosei Co., Ltd.
    Inventors: Masao Kamiya, Shinya Boyama, Yasuhisa Ushida
  • Patent number: 8518806
    Abstract: To produce a Group III nitride-based compound semiconductor having a m-plane main surface and uniformly oriented crystal axes. A mesa having a side surface having an off-angle of 45° or less from c-plane is formed in a a-plane main surface of a sapphire substrate. Subsequently, trimethylaluminum is supplied at 300° C. to 420° C., to thereby form an aluminum layer having a thickness of 40 ? or less. The aluminum layer is nitridated to form an aluminum nitride layer. Through the procedure, a Group III nitride-based compound semiconductor is epitaxially grown only from a side surface of the mesa having an off-angle of 45° or less from c-plane in the sapphire substrate having an a-plane main surface. Thus, a Group III nitride-based compound semiconductor having m-plane which is parallel to the main surface of the sapphire substrate can be formed.
    Type: Grant
    Filed: January 27, 2009
    Date of Patent: August 27, 2013
    Assignee: Toyoda Gosei Co., Ltd.
    Inventors: Koji Okuno, Shugo Nitta, Yoshiki Saito, Yasuhisa Ushida, Naoyuki Nakada, Shinya Boyama
  • Publication number: 20130017639
    Abstract: The present invention is a method for producing a light- emitting device whose p contact layer has a p-type conduction and a reduced contact resistance with an electrode. On a p cladding layer, by MOCVD, a first p contact layer of GaN doped with Mg is formed. Subsequently, after lowering the temperature to a growth temperature of a second p contact layer being formed in the subsequent process, which is 700° C., the supply of ammonia is stopped and the carrier gas is switched from hydrogen to nitrogen. Thereby, Mg is activated in the first p contact layer, and the first p contact layer has a p-type conduction. Next, the second p contact layer of InGaN doped with Mg is formed on the first p contact layer by MOCVD using nitrogen as a carrier gas while maintaining the temperature at 700° C. which is the temperature of the previous process.
    Type: Application
    Filed: July 10, 2012
    Publication date: January 17, 2013
    Applicant: Toyoda Gosei Co., Ltd.
    Inventors: Shinya BOYAMA, Yasuhisa Ushida
  • Publication number: 20120322189
    Abstract: The present invention provides a Group III nitride semiconductor light-emitting device exhibiting improved light extraction performance. In the production method, a p cladding layer of p-AlGaN is formed by the MOCVD method on a light-emitting layer at a pressure of 30 kPa and with an Mg concentration of 1.5×1020/cm3. A plurality of regions with a nitrogen polarity is formed in the crystals with a Group III element polarity, and thus the p cladding layer has a hexagonal columnar concave and convex configuration on the surface thereof. Subsequently, a p contact layer of GaN is formed by the MOCVD method, in a film along the concave and convex configuration on the p cladding layer.
    Type: Application
    Filed: June 15, 2012
    Publication date: December 20, 2012
    Applicant: Toyoda Gosei Co., Ltd.
    Inventors: Naoyuki NAKADA, Yasuhisa USHIDA
  • Publication number: 20120049236
    Abstract: A light-emitting element includes a semiconductor laminated structure including a nitride semiconductor, and formed by laminating a first semiconductor layer of a first conductivity type, a light-emitting layer and a second semiconductor layer of a second conductivity type different from the first conductivity type, the first semiconductor layer being exposed by removing a part of the second semiconductor layer and the light-emitting layer, a concave portion formed in the exposed portion of the first semiconductor layer, a first electrode formed on the concave portion and being in ohmic contact with the first semiconductor layer, and a second electrode being in ohmic contact with the second semiconductor layer and formed surrounding the first electrode.
    Type: Application
    Filed: June 10, 2011
    Publication date: March 1, 2012
    Applicant: TOYODA GOSEI CO., LTD.
    Inventors: Masao Kamiya, Shinya Boyama, Yasuhisa Ushida
  • Publication number: 20110244610
    Abstract: The present invention provides a method for producing a Group III nitride semiconductor light-emitting device whose main surface is a plane that provides an internal electric field of zero, and which exhibits improved light extraction performance. In the production method, one surface of an a-plane sapphire substrate is subjected to dry etching, to thereby form an embossment pattern having a plurality of mesas which are arranged in a honeycomb-dot pattern as viewed from above; and an n-type layer, a light-emitting layer, and a p-type layer, each of which is formed of a Group III nitride semiconductor layer having an m-plane main surface, are sequentially stacked on the surface of the sapphire substrate on which the mesas are formed. Subsequently, a p-electrode is formed on the p-type layer, and the p-electrode is bonded to a support substrate via a metal layer. Next, the sapphire substrate is removed through the laser lift-off process.
    Type: Application
    Filed: March 29, 2011
    Publication date: October 6, 2011
    Applicant: TOYODA GOSEI CO., LTD.
    Inventors: Yoshiki SAITO, Koji Okuno, Yasuhisa Ushida
  • Publication number: 20110240956
    Abstract: The present invention provides a Group III nitride semiconductor light-emitting device whose main surface is a plane which provides an internal electric field of zero, and which exhibits improved emission performance. The light-emitting device includes a sapphire substrate which has, in a surface thereof, a plurality of dents which are arranged in a stripe pattern as viewed from above; an n-contact layer formed on the dented surface of the sapphire substrate; a light-emitting layer formed on the n-contact layer; an electron blocking layer formed on the light-emitting layer; a p-contact layer formed on the electron blocking layer; a p-electrode; and an n-electrode. The electron blocking layer has a thickness of 2 to 8 nm and is formed of Mg-doped AlGaN having an Al compositional proportion of 20 to 30%.
    Type: Application
    Filed: March 25, 2011
    Publication date: October 6, 2011
    Applicant: TOYODA GOSEI CO., LTD.
    Inventors: Yoshiki Saito, Koji Okuno, Yasuhisa Ushida
  • Patent number: 7948061
    Abstract: A characteristic feature of the invention is to form, in a Group III nitride-based compound semiconductor device, a negative electrode on a surface other than a Ga-polar C-plane. In a Group III nitride-based compound semiconductor light-emitting device, there are formed, on an R-plane sapphire substrate, an n-contact layer, a layer for improving static breakdown voltage, an n-cladding layer made of a multi-layer structure having ten stacked sets of an undoped In0.1Ga0.9N layer, an undoped GaN layer, and a silicon (Si)-doped GaN layer, a multi-quantum well (MQW) light-emitting layer made of a combination of In0.25Ga0.75N well layers and GaN barrier layers stacked alternatingly, a p-cladding layer made of a multi-layer structure including a p-type Al0.3Ga0.7N layer and a p-In0.08Ga0.92N layer, and a p-contact layer (thickness: about 80 nm) made of a stacked structure including two p-GaN layers having different magnesium concentrations.
    Type: Grant
    Filed: July 25, 2008
    Date of Patent: May 24, 2011
    Assignee: Toyoda Gosei Co., Ltd.
    Inventors: Yoshiki Saito, Yasuhisa Ushida
  • Publication number: 20100308437
    Abstract: To produce a Group III nitride-based compound semiconductor having a m-plane main surface and uniformly oriented crystal axes. A mesa having a side surface having an off-angle of 45° or less from c-plane is formed in a a-plane main surface of a sapphire substrate. Subsequently, trimethylaluminum is supplied at 300° C. to 420° C., to thereby form an aluminum layer having a thickness of 40 ? or less. The aluminum layer is nitridated to form an aluminum nitride layer. Through the procedure, a Group III nitride-based compound semiconductor is epitaxially grown only from a side surface of the mesa having an off-angle of 45° or less from c-plane in the sapphire substrate having an a-plane main surface. Thus, a Group III nitride-based compound semiconductor having m-plane which is parallel to the main surface of the sapphire substrate can be formed.
    Type: Application
    Filed: January 27, 2009
    Publication date: December 9, 2010
    Inventors: Koji Okuno, Shugo Nitta, Yoshiki Saito, Yasuhisa Ushida, Naoyuki Nakada, Shinya Boyama