Patents by Inventor Seiji Sarayama

Seiji Sarayama 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: 11718927
    Abstract: There is provided a method of manufacturing a crystal substrate, including: preparing a first crystal body which is a substrate comprising a single crystal of group III nitride produced by a vapor phase method and having a first main surface, and in which c-plane of the single crystal is curved in a concave spherical shape with a predetermined curvature; and growing a second crystal body comprising a single crystal of group III nitride on the first main surface, in a mixed melt containing an alkali metal and a group III element.
    Type: Grant
    Filed: March 14, 2019
    Date of Patent: August 8, 2023
    Assignee: SUMITOMO CHEMICAL COMPANY, LIMITED
    Inventors: Takehiro Yoshida, Masatomo Shibata, Seiji Sarayama, Takashi Sato, Naoya Miyoshi, Akishige Murakami
  • Patent number: 10538858
    Abstract: In a method for manufacturing a group 13 nitride crystal, a seed crystal made of a group 13 nitride crystal is arranged in a mixed melt containing an alkali metal and a group 13 element, and nitrogen is supplied to the mixed melt to grow the group 13 nitride crystal on a principal plane of the seed crystal. The seed crystal is manufactured by vapor phase epitaxy. At least a part of contact members coming into contact with the mixed melt in a reaction vessel accommodating the mixed melt is made of Al2O3. An interface layer having a photoluminescence emission peak whose wavelength is longer than the wavelength of a photoluminescence emission peak of the grown group 13 nitride crystal is formed between the seed crystal and the grown group nitride crystal.
    Type: Grant
    Filed: February 19, 2015
    Date of Patent: January 21, 2020
    Assignee: SCIOCS COMPANY LIMITED
    Inventors: Masahiro Hayashi, Takashi Satoh, Naoya Miyoshi, Junichi Wada, Seiji Sarayama
  • Publication number: 20190292682
    Abstract: There is provided a method of manufacturing a crystal substrate, including: preparing a first crystal body which is a substrate comprising a single crystal of group III nitride produced by a vapor phase method and having a first main surface, and in which c-plane of the single crystal is curved in a concave spherical shape with a predetermined curvature; and growing a second crystal body comprising a single crystal of group III nitride on the first main surface, in a mixed melt containing an alkali metal and a group III element.
    Type: Application
    Filed: March 14, 2019
    Publication date: September 26, 2019
    Inventors: Takehiro YOSHIDA, Masatomo SHIBATA, Seiji SARAYAMA, Takashi SATO, Naoya MIYOSHI, Akishige MURAKAMI
  • Patent number: 10100426
    Abstract: A method for producing a gallium nitride crystal includes growing a gallium nitride crystal 5 by dissolving nitrogen in a mixed melt including gallium and sodium, and collecting the gallium 55 separated from an alloy 51 including the gallium and the sodium by reacting the alloy 51 and a liquid 52 that ionizes the sodium and separating sodium ions and the gallium 55 from the alloy.
    Type: Grant
    Filed: November 27, 2014
    Date of Patent: October 16, 2018
    Assignee: RICOH COMPANY, LTD.
    Inventors: Takashi Satoh, Seiji Sarayama, Masahiro Hayashi, Naoya Miyoshi, Chiharu Kimura, Junichi Wada
  • Publication number: 20180163323
    Abstract: A method for producing a group 13 nitride single crystal includes dissolving and crystal growing. The dissolving includes dissolving nitrogen in a mixed melt in a reaction vessel that contains the mixed melt, a seed crystal, and a surrounding member. The mixed melt contains an alkali metal and a group 13 metal. The seed crystal is a seed crystal that is placed in the mixed melt and includes a group 13 nitride crystal in which a principal face is a c-plane. The surrounding member is arranged so as to surround the entire area of a side face of the seed crystal. The crystal growing includes growing a group 13 nitride crystal on the seed crystal.
    Type: Application
    Filed: February 8, 2018
    Publication date: June 14, 2018
    Inventors: Takashi Satoh, Naoya Miyoshi, Junichi Wada, Masahiro Hayashi, Seiji Sarayama, Haruo Sunakawa, Yujirou Ishihara, Akira Usui
  • Patent number: 9869033
    Abstract: A crystal has a diameter of 1 cm or more and shows a strongest peak in cathode luminescent spectrum at a wavelength of 360 nm in correspondence to a band edge.
    Type: Grant
    Filed: February 11, 2015
    Date of Patent: January 16, 2018
    Assignee: RICOH COMPANY, LTD.
    Inventors: Seiji Sarayama, Masahiko Shimada, Hisanori Yamane, Hirokazu Iwata
  • Patent number: 9863058
    Abstract: A gallium nitride crystal having a hexagonal crystal structure includes a first region located on an inner side of a cross section intersecting c-axis of the hexagonal crystal structure, and a second region surrounding at least a part of the outer periphery of the first region in the cross section. An emission spectrum of each of the first region and the second region with electron beam or ultraviolet light excitation has a first peak including a band edge emission of gallium nitride and a second peak located in a longer wavelength area than the first peak. A peak intensity of the first peak is smaller than a peak intensity of the second peak in the first region, and a peak intensity of the first peak is greater than a peak intensity of the second peak in the second region.
    Type: Grant
    Filed: May 11, 2015
    Date of Patent: January 9, 2018
    Assignee: RICOH COMPANY, LTD.
    Inventors: Masahiro Hayashi, Seiji Sarayama, Takashi Satoh, Hiroshi Nambu, Chiharu Kimura, Naoya Miyoshi
  • Patent number: 9856575
    Abstract: A crystal growth apparatus comprises a reaction vessel holding a melt mixture containing an alkali metal and a group III metal, a gas supplying apparatus supplying a nitrogen source gas to a vessel space exposed to the melt mixture inside the reaction vessel, a heating unit heating the melt mixture to a crystal growth temperature, and a support unit supporting a seed crystal of a group III nitride crystal inside the melt mixture.
    Type: Grant
    Filed: September 14, 2015
    Date of Patent: January 2, 2018
    Assignee: RICOH COMPANY, LTD.
    Inventors: Seiji Sarayama, Hirokazu Iwata, Akihiro Fuse
  • Patent number: 9732435
    Abstract: A group 13 nitride crystal having a hexagonal crystal structure and containing at least a nitrogen atom and at least a metal atom selected from a group consisting of B, Al, Ga, In, and Tl. The group 13 nitride crystal includes a first region disposed on an inner side in a cross section intersecting c-axis, a third region disposed on an outermost side in the cross section and having a crystal property different from that of the first region, and a second region disposed at least partially between the first region and the third region in the cross section, the second region being a transition region of a crystal growth and having a crystal property different from that of the first region and that of the third region.
    Type: Grant
    Filed: September 10, 2012
    Date of Patent: August 15, 2017
    Assignee: RICOH COMPANY, LTD.
    Inventors: Masahiro Hayashi, Seiji Sarayama, Takashi Satoh, Hiroshi Nambu, Chiharu Kimura, Naoya Miyoshi
  • Publication number: 20170204534
    Abstract: A gallium nitride crystal having a hexagonal crystal structure, wherein a full width at half maximum (FWHM) of X-ray rocking curve in a region at a side of one edge in a c-axis direction is smaller than the FWHM in a region at a side of the other edge in the c-axis direction, in at least one of m-plane outer peripheral surfaces of the hexagonal crystal structure.
    Type: Application
    Filed: March 10, 2017
    Publication date: July 20, 2017
    Applicant: RICOH COMPANY, LTD.
    Inventors: Masahiro HAYASHI, Seiji SARAYAMA, Takashi SATOH, Hiroshi NAMBU, Chiharu KIMURA, Naoya MIYOSHI
  • Publication number: 20170022629
    Abstract: A method for producing a gallium nitride crystal includes growing a gallium nitride crystal 5 by dissolving nitrogen in a mixed melt including gallium and sodium, and collecting the gallium 55 separated from an alloy 51 including the gallium and the sodium by reacting the alloy 51 and a liquid 52 that ionizes the sodium and separating sodium ions and the gallium 55 from the alloy.
    Type: Application
    Filed: November 27, 2014
    Publication date: January 26, 2017
    Applicant: Ricoh Company, Ltd.
    Inventors: Takashi SATOH, Seiji SARAYAMA, Masahiro HAYASHI, Naoya MIYOSHI, Chiharu KIMURA, Junichi WADA
  • Publication number: 20160348272
    Abstract: In a method for manufacturing a group 13 nitride crystal, a seed crystal made of a group 13 nitride crystal is arranged in a mixed melt containing an alkali metal and a group 13 element, and nitrogen is supplied to the mixed melt to grow the group 13 nitride crystal on a principal plane of the seed crystal. The seed crystal is manufactured by vapor phase epitaxy. At least a part of contact members coming into contact with the mixed melt in a reaction vessel accommodating the mixed melt is made of Al2O3. An interface layer having a photoluminescence emission peak whose wavelength is longer than the wavelength of a photoluminescence emission peak of the grown group 13 nitride crystal is formed between the seed crystal and the grown group nitride crystal.
    Type: Application
    Filed: February 19, 2015
    Publication date: December 1, 2016
    Applicant: Ricoh Company, Ltd
    Inventors: Masahiro HAYASHI, Takashi SATOH, Naoya MIYOSHI, Junichi Wada, Seiji SARAYAMA
  • Patent number: 9404196
    Abstract: A method of manufacturing a group 13 nitride crystal includes a crystal growth process to form the group 13 nitride crystal by growing the group 13 nitride crystal having a hexagonal crystal structure from a seed crystal which is a gallium nitride crystal having a hexagonal crystal structure in which a length “L” in a c-axis direction is 9.7 mm or more, and a ratio L/d of the length “L” to a crystal diameter “d” in a c-plane is larger than 0.813. The crystal growth process includes a process of forming an outer periphery containing a {10-10} plane and an outer periphery containing a {10-11} plane at side surfaces of the group 13 nitride crystal, and forming an outer periphery containing a {0001} plane at a bottom surface of the group 13 nitride crystal.
    Type: Grant
    Filed: August 23, 2012
    Date of Patent: August 2, 2016
    Assignee: RICOH COMPANY, LTD.
    Inventors: Masahiro Hayashi, Seiji Sarayama, Takashi Satoh, Hiroshi Nambu, Chiharu Kimura, Naoya Miyoshi
  • Patent number: 9376763
    Abstract: A method for manufacturing a group III nitride crystal on a seed crystal in a holding vessel holding therein a melt containing a group III metal, an alkali metal and nitrogen. The manufacturing method comprises the steps of causing the seed crystal to make a contact with the melt, setting an environment of the seed crystal to a first state offset from a crystal growth condition while in a state in which said seed crystal is in contact with the melt, increasing a nitrogen concentration in the melt, and setting the environment of the seed crystal to a second state suitable for crystal growth when the nitrogen concentration of the melt has reached a concentration suitable for growing the seed crystal.
    Type: Grant
    Filed: November 16, 2012
    Date of Patent: June 28, 2016
    Assignee: RICOH COMPANY, LTD.
    Inventors: Hirokazu Iwata, Seiji Sarayama, Minoru Fukuda, Tetsuya Takahashi, Akira Takahashi
  • Publication number: 20160177468
    Abstract: A method is for manufacturing a group 13 nitride crystal by a flux method. The method includes: placing a seed crystal and a mixed melt that contains an alkali metal or an alkali-earth metal and a group 13 element in a reaction vessel; and rotating the reaction vessel to stir the mixed melt. The reaction vessel includes a structure to stir the mixed melt. More than one seed crystals are installed point-symmetrically with respect to a central axis of the reaction vessel at positions other than the central axis such that a c plane of each of the seed crystals is substantially parallel to a bottom of the reaction vessel. The structure is installed point-symmetrically with respect to the central axis at at least part of the reaction vessel other than the central axis.
    Type: Application
    Filed: August 5, 2014
    Publication date: June 23, 2016
    Applicant: RICOH COMPANY, LIMITED.
    Inventors: Takashi SATOH, Seiji SARAYAMA, Masahiro HAYASHI, Junichi WADA
  • Publication number: 20160168747
    Abstract: An apparatus is used for manufacturing a group 13 nitride crystal by using a flux method. The apparatus includes a reaction vessel, a rotational mechanism, and a structure. The reaction vessel contains a mixed melt and a seed crystal placed in the mixed melt. The mixed melt contains an alkali metal or an alkali-earth metal and a group 13 element. The rotational mechanism rotates the reaction vessel. The structure is provided inside the reaction vessel for stirring the mixed melt and is constructed such that a height of a first portion of the structure close to an inner wall of the reaction vessel is higher than a height of a second portion of the structure close to a center of the reaction vessel.
    Type: Application
    Filed: August 5, 2014
    Publication date: June 16, 2016
    Applicant: RICOH COMPANY, LTD.
    Inventors: Yusuke MORI, Takashi SATOH, Masahiro HAYASHI, Seiji SARAYAMA, Yoshikazu KATO
  • Patent number: 9365948
    Abstract: A group III nitride crystal containing therein an alkali metal element comprises a base body, a first group III nitride crystal formed such that at least a part thereof makes a contact with the base body, the first group III nitride crystal deflecting threading dislocations in a direction different from a direction of crystal growth from the base body and a second nitride crystal formed adjacent to the first group III nitride crystal, the second nitride crystal having a crystal growth surface generally perpendicular to the direction of the crystal growth.
    Type: Grant
    Filed: October 8, 2012
    Date of Patent: June 14, 2016
    Assignee: RICOH COMPANY, LTD
    Inventors: Hirokazu Iwata, Seiji Sarayama, Akihiro Fuse
  • Publication number: 20160002818
    Abstract: A crystal growth apparatus comprises a reaction vessel holding a melt mixture containing an alkali metal and a group III metal, a gas supplying apparatus supplying a nitrogen source gas to a vessel space exposed to the melt mixture inside the reaction vessel, a heating unit heating the melt mixture to a crystal growth temperature, and a support unit supporting a seed crystal of a group III nitride crystal inside the melt mixture.
    Type: Application
    Filed: September 14, 2015
    Publication date: January 7, 2016
    Inventors: Seiji SARAYAMA, Hirokazu Iwata, Akihiro Fuse
  • Patent number: 9222199
    Abstract: A crystal manufacturing apparatus for manufacturing a group III nitride crystal includes a crucible that holds a mixed molten liquid including an alkali metal and a group III metal; a reaction vessel accommodating the crucible in the reaction vessel; a heating device that heats the crucible with the reaction vessel; a holding vessel having a lid that is capable of opening and closing, accommodating the reaction vessel and the heating device in the holding vessel; a sealed vessel accommodating the holding vessel in the sealed vessel, having an operating device that enables opening the lid of the holding vessel for supplying source materials into the crucible and taking out a manufactured GaN crystal under a sealed condition, and closing the lid of the holding vessel that is sealed in the sealed vessel, the sealed vessel including an inert gas atmosphere or a nitrogen atmosphere; and a gas supplying device for supplying a nitrogen gas to the mixed molten liquid through each of the vessels.
    Type: Grant
    Filed: March 29, 2010
    Date of Patent: December 29, 2015
    Assignee: RICOH COMPANY, LTD.
    Inventors: Seiji Sarayama, Hirokazu Iwata
  • Publication number: 20150315723
    Abstract: A nitride crystal which encircles an outer periphery of a seed crystal, the nitride crystal in an embodiment includes: a first partial region, and a second partial region that has optical characteristics different from those of the first partial region and has optical characteristics which indicate the crystal orientation.
    Type: Application
    Filed: June 23, 2015
    Publication date: November 5, 2015
    Applicants: RICOH COMPANY, LIMITED, OSAKA UNIVERSITY
    Inventors: Takashi Satoh, Seiji SARAYAMA, Hirokazu IWATA, Yusuke MORI, Yasuo KITAOKA