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).

  • Publication number: 20090120354
    Abstract: A group-III nitride crystal growth method comprises the steps of: a) preparing a mixed molten liquid of an alkaline material and a substance at least containing a group-III metal; b) causing growth of a group-III nitride crystal from the mixed molten liquid prepared in the step a) and a substance at least containing nitrogen; and c) creating a state in which nitrogen can be introduced into the molten liquid prepared by the step a).
    Type: Application
    Filed: January 14, 2009
    Publication date: May 14, 2009
    Inventors: Seiji Sarayama, Hisanori Yamane, Masahiko Shimada, Masafumi Kumano, Hirokazu Iwata, Takashi Araki
  • Patent number: 7531038
    Abstract: A group-III nitride crystal growth method comprises the steps of: a) preparing a mixed molten liquid of an alkaline material and a substance at least containing a group-III metal; b) causing growth of a group-III nitride crystal from the mixed molten liquid prepared in the step a) and a substance at least containing nitrogen; and c) creating a state in which nitrogen can be introduced into the molten liquid prepared by the step a).
    Type: Grant
    Filed: December 14, 2005
    Date of Patent: May 12, 2009
    Assignee: Ricoh Company, Ltd.
    Inventors: Seiji Sarayama, Hisanori Yamane, Masahiko Shimada, Masafumi Kumano, Hirokazu Iwata, Takashi Araki
  • Patent number: 7508003
    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: April 20, 2006
    Date of Patent: March 24, 2009
    Assignee: Ricoh Company, Ltd.
    Inventors: Seiji Sarayama, Masahiko Shimada, Hisanori Yamane, Hirokazu Iwata
  • Patent number: 7462238
    Abstract: A crystal growth apparatus comprises a reaction vessel holding a melt mixture containing an alkali metal and a group III metal in a vessel space thereof, a porous member holding a metal melt by a surface tension thereof in a path through which a vapor of the alkali metal in contact with the metal mixture in the vessel space escapes to an external space, the porous member further supplying a nitrogen source gas fed from outside thereto further to the reaction vessel therethrough and through the metal melt by a pressure difference formed between the vessel space in the reaction vessel and the external space, and a heating apparatus heating the melt mixture to a crystal growth temperature.
    Type: Grant
    Filed: August 4, 2006
    Date of Patent: December 9, 2008
    Assignees: Ricoh Company, Ltd., Japan Atomic Energy Agency
    Inventors: Seiji Sarayama, Hirokazu Iwata, Akihiro Fuse, Kuniaki Ara, Junichi Saito
  • Publication number: 20080282969
    Abstract: A crystal growth method, comprising the steps of: a) bringing a nitrogen material into a reaction vessel in which a mixed molten liquid comprising an alkaline metal and a group-III metal; and b) growing a crystal of a group-III nitride using the mixed molten liquid and the nitrogen material brought in by the step a) in the reaction vessel, wherein a provision is made such as to prevent a vapor of the alkaline metal from dispersing out of the reaction vessel.
    Type: Application
    Filed: June 13, 2008
    Publication date: November 20, 2008
    Applicant: Ricoh Company, Ltd,
    Inventors: Seiji Sarayama, Masahiko Shimada, Hisanori Yamane, Masato Aoki
  • Publication number: 20080264331
    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: Application
    Filed: March 13, 2006
    Publication date: October 30, 2008
    Inventors: Hirokazu Iwata, Seiji Sarayama, Minoru Fukuda, Tetsuya Takahashi, Akira Takahashi
  • Publication number: 20080220346
    Abstract: A photoreceptor includes a conductive support body, an intermediate layer, and a photosensitive layer. The intermediate layer is made of gallium nitride (GaN) crystals having electron affinity greater than that of the photosensitive layer and formed between and in contact with the conductive support body and the photosensitive layer. The photosensitive layer is composed of either a single layer type photosensitive layer or a laminated type photosensitive layer.
    Type: Application
    Filed: February 1, 2008
    Publication date: September 11, 2008
    Applicant: Ricoh Company, Ltd
    Inventors: Seiji SARAYAMA, Tetsuya Toshine
  • Publication number: 20080216737
    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: Application
    Filed: March 5, 2008
    Publication date: September 11, 2008
    Inventors: Seiji Sarayama, Hirokazu Iwata
  • Publication number: 20080081015
    Abstract: A crystal producing apparatus includes a crystal forming unit and a crystal growing unit. The crystal forming unit forms a first gallium nitride (GaN) crystal by supplying nitride gas into melt mixture containing metal sodium (Na) and metal gallium (Ga). The first GaN crystal is sliced and polished to form GaN wafers. The crystal growing unit grows a second GaN crystal on a substrate formed by using a GaN wafer, by the hydride vapor phase epitaxy method, thus producing a bulked GaN crystal.
    Type: Application
    Filed: October 1, 2007
    Publication date: April 3, 2008
    Inventors: Seiji Sarayama, Hirokazu Iwata
  • Publication number: 20070266928
    Abstract: A method of growing a group III nitride crystal grows a group III nitride crystal from a solution in which an alkaline metal, a group III metal and nitrogen are dissolved, and includes, in the solution, a material which increases solubility of the nitrogen into the solution.
    Type: Application
    Filed: July 20, 2007
    Publication date: November 22, 2007
    Inventors: Hirokazu Iwata, Seiji Sarayama, Hisanori Yamane, Masahiko Shimada, Masato Aoki
  • Publication number: 20070215034
    Abstract: In a crystal preparing device, a crucible holds a mixed molten metal containing alkali metal and group III metal. A container has a container space contacting the mixed molten metal and holds a molten alkali metal between the container space and an outside of the container, the molten alkali metal contacting the container space. A gas supply device supplies nitrogen gas to the container space. A heating device heats the crucible to a crystal growth temperature. The crystal preparing device is provided so that a vapor pressure of the alkali metal which evaporates from the molten alkali metal is substantially equal to a vapor pressure of the alkali metal which evaporates from the mixed molten metal.
    Type: Application
    Filed: March 12, 2007
    Publication date: September 20, 2007
    Inventors: Hirokazu Iwata, Seiji Sarayama, Akihiro Fuse
  • Patent number: 7261775
    Abstract: A method of growing a group III nitride crystal grows a group III nitride crystal from a solution in which an alkaline metal, a group III metal and nitrogen are dissolved, and includes, in the solution, a material which increases solubility of the nitrogen into the solution.
    Type: Grant
    Filed: January 28, 2004
    Date of Patent: August 28, 2007
    Assignee: Ricoh Company, Ltd.
    Inventors: Hirokazu Iwata, Seiji Sarayama, Hisanori Yamane, Masahiko Shimada, Masato Aoki
  • Publication number: 20070194408
    Abstract: A crystal growth method of a group III nitride includes the steps of forming a melt mixture of an alkali metal and a group III element in a reaction vessel, and growing a crystal of a group III nitride formed of the group III element and nitrogen from the melt mixture in the reaction vessel, wherein the step of growing the crystal of the group III nitride is conducted while controlling an increase rate of degree of supersaturation of a group III nitride component in the melt mixture in a surface region of the melt mixture.
    Type: Application
    Filed: April 13, 2007
    Publication date: August 23, 2007
    Inventors: Hirokazu Iwata, Seiji Sarayama
  • Patent number: 7250640
    Abstract: A method of making a bulk crystal substrate of a GaN single crystal includes the steps of forming a molten flux of an alkali metal in a reaction vessel and causing a growth of a GaN single crystal from the molten flux, wherein the growth is continued while replenishing a compound containing N from a source outside the reaction vessel.
    Type: Grant
    Filed: June 13, 2003
    Date of Patent: July 31, 2007
    Assignee: Ricoh Company, Ltd.
    Inventors: Seiji Sarayama, Masahiko Shimada, Hisanori Yamane, Hirokazu Iwata
  • Publication number: 20070128746
    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: Application
    Filed: November 20, 2006
    Publication date: June 7, 2007
    Inventors: Hirokazu Iwata, Seiji Sarayama, Akihiro Fuse
  • Patent number: 7220311
    Abstract: A crystal growth method of a group III nitride includes the steps of forming a melt mixture of an alkali metal and a group III element in a reaction vessel, and growing a crystal of a group III nitride formed of the group III element and nitrogen from the melt mixture in the reaction vessel, wherein the step of growing the crystal of the group III nitride is conducted while controlling an increase rate of degree of supersaturation of a group III nitride component in the melt mixture in a surface region of the melt mixture.
    Type: Grant
    Filed: November 7, 2003
    Date of Patent: May 22, 2007
    Assignee: Ricoh Company, Ltd.
    Inventors: Hirokazu Iwata, Seiji Sarayama
  • Publication number: 20070084399
    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: October 13, 2006
    Publication date: April 19, 2007
    Inventors: Seiji Sarayama, Hirokazu Iwata, Akihiro Fuse
  • Publication number: 20070034143
    Abstract: A crystal growth apparatus comprises a reaction vessel holding a melt mixture containing an alkali metal and a group III metal in a vessel space thereof, a porous member holding a metal melt by a surface tension thereof in a path through which a vapor of the alkali metal in contact with the metal mixture in the vessel space escapes to an external space, the porous member further supplying a nitrogen source gas fed from outside thereto further to the reaction vessel therethrough and through the metal melt by a pressure difference formed between the vessel space in the reaction vessel and the external space, and a heating apparatus heating the melt mixture to a crystal growth temperature.
    Type: Application
    Filed: August 4, 2006
    Publication date: February 15, 2007
    Inventors: Seiji Sarayama, Hirokazu Iwata, Akihiro Fuse, Kuniaki Ara, Junichi Saito
  • Publication number: 20070012239
    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: Application
    Filed: April 20, 2006
    Publication date: January 18, 2007
    Inventors: Seiji Sarayama, Masahiko Shimada, Hisanori Yamane, Hirokazu Iwata
  • Publication number: 20060130739
    Abstract: A group-III nitride crystal growth method comprises the steps of: a) preparing a mixed molten liquid of an alkaline material and a substance at least containing a group-III metal; b) causing growth of a group-III nitride crystal from the mixed molten liquid prepared in the step a) and a substance at least containing nitrogen; and c) creating a state in which nitrogen can be introduced into the molten liquid prepared by the step a).
    Type: Application
    Filed: December 14, 2005
    Publication date: June 22, 2006
    Inventors: Seiji Sarayama, Hisanori Yamane, Masahiko Shimada, Masafumi Kumano, Hirokazu Iwata, Takashi Araki