Patents by Inventor Takanao Shimodaira
Takanao Shimodaira 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: 20160355945Abstract: It is used a crucible containing a flux and a source material, a reaction vessel containing the crucible, an intermediate vessel containing the reaction vessel, and a pressure vessel containing the intermediate vessel and used to fill a gas comprising at least a nitrogen atom. When the flux and the source material are melted by heating to grow the nitride crystal, a vapor of an organic compound is provided in a space outside of the reaction vessel and inside of the intermediate vessel.Type: ApplicationFiled: August 17, 2016Publication date: December 8, 2016Applicant: NGK INSULATORS, LTD.Inventors: Katsuhiro Imai, Makoto Iwai, Masahiro Sakai, Takanao Shimodaira, Shuhei Higashihara, Takayuki Hirao
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Patent number: 9290861Abstract: Regarding a base substrate, a plurality of steps are formed stepwise on the principal surface (c-face). Each step has a height difference of 10 to 40 ?m, and an edge is formed parallel to an a-face of a hexagonal crystal of GaN. Meanwhile, the terrace width of each step is set at a predetermined width. The predetermined width is set in such a way that after a GaN crystal is grown on the principal surface of the base substrate, the principal surface is covered up with grain boundaries when the grown GaN crystal is observed from the surface side. The plurality of steps can be formed through, for example, dry etching, sand blasting, lasing, and dicing.Type: GrantFiled: October 15, 2010Date of Patent: March 22, 2016Assignee: NGK INSULATORS, LTD.Inventors: Takayuki Hirao, Takanao Shimodaira, Katsuhiro Imai
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Patent number: 9017479Abstract: The apparatus has a crucible for storing a solution; an inner container for storing a crucible; a heating container for storing the inner container, the heating container including heating elements, a container body provided with the heating elements and a lid combined with the container body; and a pressure vessel for storing the heating container and for charging an atmosphere comprising at least nitrogen gas. The lid also has a fitting surface to the container body that is inclined to a horizontal plane.Type: GrantFiled: July 29, 2008Date of Patent: April 28, 2015Assignees: NGK Insulators, Ltd., Osaka University, Toyoda Gosei Co., Ltd.Inventors: Makoto Iwai, Takanao Shimodaira, Takatomo Sasaki, Yusuke Mori, Fumio Kawamura, Shiro Yamasaki
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Patent number: 8999059Abstract: A growth apparatus is used having a plurality of crucibles each for containing the solution, a heating element for heating the crucible, and a pressure vessel for containing at least the crucibles and the heating element and for filling an atmosphere comprising at least nitrogen gas. One seed crystal is put in each of the crucibles to grow the nitride single crystal on the seed crystal.Type: GrantFiled: September 22, 2008Date of Patent: April 7, 2015Assignees: NGK Insulators, Ltd., Osaka UniversityInventors: Katsuhiro Imai, Makoto Iwai, Takanao Shimodaira, Takatomo Sasaki, Yusuke Mori, Fumio Kawamura
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Patent number: 8795431Abstract: A gallium nitride layer is produced using a seed crystal substrate by flux method. The seed crystal substrate 8A includes a supporting body 1, a plurality of seed crystal layers 4A each comprising gallium nitride single crystal and separated from one another, a low temperature buffer layer 2 provided between the seed crystal layers 4A and the supporting body and made of a nitride of a group III metal element, and an exposed layer 3 exposed to spaces between the adjacent seed crystal layers 4A and made of aluminum nitride single crystal or aluminum gallium nitride single crystal. The gallium nitride layer is grown on the seed crystal layers by flux method.Type: GrantFiled: September 20, 2013Date of Patent: August 5, 2014Assignee: NGK Insulators, Ltd.Inventors: Katsuhiro Imai, Makota Iwai, Takanao Shimodaira, Masahiro Sakai, Shuhei Higashihara, Takayuki Hirao
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Patent number: 8729672Abstract: To grow a gallium nitride crystal, a seed-crystal substrate is first immersed in a melt mixture containing gallium and sodium. Then, a gallium nitride crystal is grown on the seed-crystal substrate under heating the melt mixture in a pressurized atmosphere containing nitrogen gas and not containing oxygen. At this time, the gallium nitride crystal is grown on the seed-crystal substrate under a first stirring condition of stirring the melt mixture, the first stirring condition being set for providing a rough growth surface, and the gallium nitride crystal is subsequently grown on the seed-crystal substrate under a second stirring condition of stirring the melt mixture, the second stirring condition being set for providing a smooth growth surface.Type: GrantFiled: April 12, 2013Date of Patent: May 20, 2014Assignee: NGK Insulators, Ltd.Inventors: Takanao Shimodaira, Takayuki Hirao, Katsuhiro Imai
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Patent number: 8657955Abstract: It is provided a melt composition for growing a gallium nitride single crystal by flux method. The melt composition contains gallium, sodium and barium, and a content of barium is 0.05 to 0.3 mol % with respect to 100 mol % of sodium.Type: GrantFiled: August 3, 2009Date of Patent: February 25, 2014Assignees: NGK Insulators, Ltd, Osaka University, Toyoda Gosei Co., Ltd.Inventors: Makoto Iwai, Takanao Shimodaira, Yoshihiko Yamamura, Takatomo Sasaki, Yusuke Mori, Fumio Kawamura, Shiro Yamasaki
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Publication number: 20140026809Abstract: A seed crystal substrate 10 includes a supporting body 1, and a seed crystal film 3A formed on the supporting body 1 and composed of a single crystal of a nitride of a Group 13 metal element. The seed crystal film 3A includes main body parts 3a and thin parts 3b having a thickness smaller than that of the main body parts 3a. The main body parts 3a and thin part 3b are exposed to a surface of the seed crystal substrate 10. A nitride 15 of a Group 13 metal element is grown on the seed crystal film 3A by flux method.Type: ApplicationFiled: September 17, 2013Publication date: January 30, 2014Applicant: NGK INSULATORS, LTD.Inventors: Makoto Iwai, Takanao Shimodaira, Shuhei Higashihara, Takayuki Hirao, Masahiro Sakai, Katsuhiro Imai
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Publication number: 20140014028Abstract: A gallium nitride layer is produced using a seed crystal substrate by flux method. The seed crystal substrate 8A includes a supporting body 1, a plurality of seed crystal layers 4A each comprising gallium nitride single crystal and separated from one another, a low temperature buffer layer 2 provided between the seed crystal layers 4A and the supporting body and made of a nitride of a group III metal element, and an exposed layer 3 exposed to spaces between the adjacent seed crystal layers 4A and made of aluminum nitride single crystal or aluminum gallium nitride single crystal. The gallium nitride layer is grown on the seed crystal layers by flux method.Type: ApplicationFiled: September 20, 2013Publication date: January 16, 2014Applicant: NGK INSULATORS, LTD.Inventors: Katsuhiro Imai, Makoto Iwai, Takanao Shimodaira, Masahiro Sakai, Shuhei Higashihara, Takayuki Hirao
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Patent number: 8440017Abstract: To grow a gallium nitride crystal, a seed-crystal substrate is first immersed in a melt mixture containing gallium and sodium. Then, a gallium nitride crystal is grown on the seed-crystal substrate under heating the melt mixture in a pressurized atmosphere containing nitrogen gas and not containing oxygen. At this time, the gallium nitride crystal is grown on the seed-crystal substrate under a first stirring condition of stirring the melt mixture, the first stirring condition being set for providing a rough growth surface, and the gallium nitride crystal is subsequently grown on the seed-crystal substrate under a second stirring condition of stirring the melt mixture, the second stirring condition being set for providing a smooth growth surface.Type: GrantFiled: August 12, 2011Date of Patent: May 14, 2013Assignee: NGK Insulators, Ltd.Inventors: Takanao Shimodaira, Takayuki Hirao, Katsuhiro Imai
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Patent number: 8231729Abstract: It is disclosed an apparatus for growing a nitride single crystal using a flux containing an easily oxidizable substance. The apparatus has a crucible for storing the flux; a pressure vessel for storing the crucible and charging an atmosphere containing at least nitrogen gas; furnace materials disposed within the pressure vessel and out of the crucible; heaters attached to the furnace material; and alkali-resistant and heat-resistant metallic layers covering the furnace material.Type: GrantFiled: August 15, 2008Date of Patent: July 31, 2012Assignees: NGK Insulators, Ltd., Osaka University, Toyoda Gosei Co., Ltd.Inventors: Makoto Iwai, Takanao Shimodaira, Takatomo Sasaki, Yusuke Mori, Fumio Kawamura, Shiro Yamasaki
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Patent number: 8227324Abstract: A GaN single crystal 20 is grown on a crystal growth surface of a seed crystal (GaN layer 13) through the flux method in a nitrogen (N2) atmosphere at 3.7 MPa and 870° C. employing a flux mixture including Ga, Na, and Li at about 870° C. Since the back surface of the template 10 is R-plane of the sapphire substrate 11, the template 10 is readily corroded or dissolved in the flux mixture from the back surface thereof. Therefore, the template 10 is gradually dissolved or corroded from the back surface thereof, resulting in separation from the semiconductor or dissolution in the flux. When the GaN single crystal 20 is grown to a sufficient thickness, for example, about 500 ?m or more, the temperature of the crucible is maintained at 850° C. to 880° C., whereby the entirety of the sapphire substrate 11 is dissolved in the flux mixture.Type: GrantFiled: December 10, 2007Date of Patent: July 24, 2012Assignees: Toyoda Gosei Co., Ltd., NGK Insulators, Ltd., Osaka UniversityInventors: Shiro Yamazaki, Makoto Iwai, Takanao Shimodaira, Takatomo Sasaki, Yusuke Mori, Fumio Kawamura
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Publication number: 20120175740Abstract: Regarding a base substrate, a plurality of steps are formed stepwise on the principal surface (c-face). Each step has a height difference of 10 to 40 ?m, and an edge is formed parallel to an a-face of a hexagonal crystal of GaN. Meanwhile, the terrace width of each step is set at a predetermined width. The predetermined width is set in such a way that after a GaN crystal is grown on the principal surface of the base substrate, the principal surface is covered up with grain boundaries when the grown GaN crystal is observed from the surface side. The plurality of steps can be formed through, for example, dry etching, sand blasting, lasing, and dicing.Type: ApplicationFiled: October 15, 2010Publication date: July 12, 2012Inventors: Takayuki Hirao, Takanao Shimodaira, Katsuhiro Imai
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Publication number: 20120111264Abstract: A plurality of seed crystal films of a single crystal of a nitride of a metal belonging to group III are formed on a substrate, while a non-growth surface not covered with the seed crystal films is formed on the substrate. A single crystal of a nitride of a metal belonging to group III is grown on the seed crystal film. A plurality of the seed crystal films are separated by the non-growth surface and arranged in at least two directions X and Y. The maximum inscribed circle diameter “A” of the seed crystal film is 50 ?m or more and 6 mm or less, a circumscribed circle diameter “B” of the seed crystal film is 50 ?m or more and 10 mm or less, and the maximum inscribed circle diameter “C” of the non-growth surface 1b is 100 ?m or more and 1 mm or less.Type: ApplicationFiled: January 6, 2012Publication date: May 10, 2012Inventors: Takanao Shimodaira, Katsuhiro Imai, Makoto Iwai
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Patent number: 8123856Abstract: In the flux method, a source nitrogen gas is sufficiently heated before feeding to an Na—Ga mixture. The apparatus of the invention is provided for producing a group III nitride based compound semiconductor. The apparatus includes a reactor which maintains a group III metal and a metal differing from the group III metal in a molten state, a heating apparatus for heating the reactor, an outer vessel for accommodating the reactor and the heating apparatus, and a feed pipe for feeding a gas containing at least nitrogen from the outside of the outer vessel into the reactor. The feed pipe has a zone for being heated together with the reactor by means of the heating apparatus, wherein the zone is heated inside the outer vessel and outside the reactor.Type: GrantFiled: April 5, 2007Date of Patent: February 28, 2012Assignees: Toyoda Gosei Co., Ltd., NGK Insulators, Ltd., Osaka UniversityInventors: Shiro Yamazaki, Makoto Iwai, Takanao Shimodaira, Takatomo Sasaki, Yusuke Mori, Fumio Kawamura
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Publication number: 20120012984Abstract: To grow a gallium nitride crystal, a seed-crystal substrate is first immersed in a melt mixture containing gallium and sodium. Then, a gallium nitride crystal is grown on the seed-crystal substrate under heating the melt mixture in a pressurized atmosphere containing nitrogen gas and not containing oxygen. At this time, the gallium nitride crystal is grown on the seed-crystal substrate under a first stirring condition of stirring the melt mixture, the first stirring condition being set for providing a rough growth surface, and the gallium nitride crystal is subsequently grown on the seed-crystal substrate under a second stirring condition of stirring the melt mixture, the second stirring condition being set for providing a smooth growth surface.Type: ApplicationFiled: August 12, 2011Publication date: January 19, 2012Applicant: NGK Insulators, Ltd.Inventors: Takanao SHIMODAIRA, Takayuki Hirao, Katsuhiro Imai
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Publication number: 20110274609Abstract: A group 13 nitride crystal substrate according to the present invention is produced by growing a group 13 nitride crystal on a seed-crystal substrate by a flux method, wherein a content of inclusions in the group 13 nitride crystal grown in a region of the seed-crystal substrate except for a circumferential portion of the seed-crystal substrate, the region having an area fraction of 70% relative to an entire area of the seed-crystal substrate, is 10% or less, preferably 2% or less.Type: ApplicationFiled: July 15, 2011Publication date: November 10, 2011Applicant: NGK Insulators, Ltd.Inventors: Takanao Shimodaira, Katsuhiro Imai, Makoto Iwai, Takayuki Hirao
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Patent number: 7842133Abstract: In a method of growing a single crystal by melting a raw material within a vessel under a nitrogenous and non-oxidizing atmosphere, the vessel is oscillated and the melted raw material is contacted with an agitation medium made of a solid unreactive with the melted raw material.Type: GrantFiled: August 12, 2008Date of Patent: November 30, 2010Assignees: NGK Insulators, Ltd., Osaka University, Toyoda Gosei Co., Ltd.Inventors: Makoto Iwai, Takanao Shimodaira, Shuhei Higashihara, Takatomo Sasaki, Yusuke Mori, Fumio Kawamura, Shiro Yamasaki, Koji Hirata
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Publication number: 20100093157Abstract: A GaN single crystal 20 is grown on a crystal growth surface of a seed crystal (GaN layer 13) through the flux method in a nitrogen (N2) atmosphere at 3.7 MPa and 870° C. employing a flux mixture including Ga, Na, and Li at about 870° C. Since the back surface of the template 10 is R-plane of the sapphire substrate 11, the template 10 is readily corroded or dissolved in the flux mixture from the back surface thereof. Therefore, the template 10 is gradually dissolved or corroded from the back surface thereof, resulting in separation from the semiconductor or dissolution in the flux. When the GaN single crystal 20 is grown to a sufficient thickness, for example, about 500 ?m or more, the temperature of the crucible is maintained at 850° C. to 880° C., whereby the entirety of the sapphire substrate 11 is dissolved in the flux mixture.Type: ApplicationFiled: December 10, 2007Publication date: April 15, 2010Inventors: Shiro Yamazaki, Makoto Iwai, Takanao Shimodaira, Takatomo Sasaki, Yusuke Mori, Fumio Kawamura
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Publication number: 20090293805Abstract: It is provided a melt composition for growing a gallium nitride single crystal by flux method. The melt composition contains gallium, sodium and barium, and a content of barium is 0.05 to 0.3 mol % with respect to 100 mol % of sodium.Type: ApplicationFiled: August 3, 2009Publication date: December 3, 2009Applicants: NGK Insulators, Ltd., Osaka University, Toyoda Gosei Co., Ltd.Inventors: Makoto Iwai, Takanao Shimodaira, Yoshihiko Yamamura, Takatomo Sasaki, Yusuke Mori, Fumio Kawamura, Shiro Yamasaki