Patents by Inventor Takayuki Yuasa
Takayuki Yuasa 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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Patent number: 7462882Abstract: A nitride semiconductor laser device has a nitride semiconductor substrate that includes a dislocation-concentrated region 102 and a wide low-dislocation region and that has the top surface thereof slanted at an angle in the range of 0.3° to 0.7° relative to the C plane and a nitride semiconductor layer laid on top thereof. The nitride semiconductor layer has a depression immediately above the dislocation-concentrated region, and has, in a region thereof other than the depression, a high-quality quantum well active layer with good flatness and without cracks, a layer that, as is grown, readily exhibits p-type conductivity, and a stripe-shaped laser light waveguide region. The laser light waveguide region is formed above the low-dislocation region. This helps realize a nitride semiconductor laser device that offers a longer life.Type: GrantFiled: April 26, 2004Date of Patent: December 9, 2008Assignees: Sharp Kabushiki Kaisha, Sumitomo Electric Industries, Ltd.Inventors: Yoshihiro Ueta, Teruyoshi Takakura, Takeshi Kamikawa, Yuhzoh Tsuda, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
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Publication number: 20080087905Abstract: A nitride compound semiconductor light emitting device includes: a GaN substrate having a crystal orientation which is tilted away from a <0001> direction by an angle which is equal to or greater than about 0.05° and which is equal to or less than about 2°, and a semiconductor multilayer structure formed on the GaN substrate, wherein the semiconductor multilayer structure includes: an acceptor doping layer containing a nitride compound semiconductor; and an active layer including a light emitting region.Type: ApplicationFiled: November 16, 2007Publication date: April 17, 2008Applicant: SHARP KABUSHIKI KAISHAInventors: Yoshihiro UETA, Takayuki YUASA, Atsushi OGAMA, Yuhzoh TSUDA, Masahiro ARAKI
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Patent number: 7352012Abstract: A nitride compound semiconductor light emitting device includes: a GaN substrate having a crystal orientation which is tilted away from a <0001> direction by an angle which is equal to or greater than about 0.05° and which is equal to or less than about 2°, and a semiconductor multilayer structure formed on the GaN substrate, wherein the semiconductor multilayer structure includes: an acceptor doping layer containing a nitride compound semiconductor; and an active layer including a light emitting region.Type: GrantFiled: April 20, 2006Date of Patent: April 1, 2008Assignee: Sharp Kabushiki KaishaInventors: Yoshihiro Ueta, Takayuki Yuasa, Atsushi Ogawa, Yuhzoh Tsuda, Masahiro Araki
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Publication number: 20070194693Abstract: Disclosed is a light-emitting device comprising a semiconductor excitation light source emitting blue-violet light and a solid material illuminant having an absorbent for the blue-violet light containing samarium (Sm). With such a constitution, the light-emitting device has high efficiency, long life and excellent color rendering properties.Type: ApplicationFiled: March 22, 2005Publication date: August 23, 2007Inventors: Hajime Saito, Mototaka Taneya, Takayuki Yuasa, Tatsuya Ryowa, Setsuhisa Tanabe, Yoichiu Kawakami, Shizuo Fujita, Mitsuru Funato
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Publication number: 20060202188Abstract: A nitride semiconductor laser device has a nitride semiconductor substrate that includes a dislocation-concentrated region 102 and a wide low-dislocation region and that has the top surface thereof slanted at an angle in the range of 0.3° to 0.7° relative to the C plane and a nitride semiconductor layer laid on top thereof. The nitride semiconductor layer has a depression immediately above the dislocation-concentrated region, and has, in a region thereof other than the depression, a high-quality quantum well active layer with good flatness and without cracks, a layer that, as is grown, readily exhibits p-type conductivity, and a stripe-shaped laser light waveguide region. The laser light waveguide region is formed above the low-dislocation region. This helps realize a nitride semiconductor laser device that offers a longer life.Type: ApplicationFiled: May 18, 2006Publication date: September 14, 2006Applicants: SHARP KABUSHIKI KAISHA, SUMITOMO ELECTRIC INDUSTRIES, LTD.Inventors: Yoshihiro Ueta, Teruyoshi Takakura, Takeshi Kamikawa, Yuhzoh Tsuda, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
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Publication number: 20060189012Abstract: A nitride compound semiconductor light emitting device includes: a GaN substrate having a crystal orientation which is tilted away from a <0001> direction by an angle which is equal to or greater than about 0.05° and which is equal to or less than about 2°, and a semiconductor multilayer structure formed on the GaN substrate, wherein the semiconductor multilayer structure includes an acceptor doping layer containing a nitride compound semiconductor; and an active layer including a light emitting region.Type: ApplicationFiled: April 20, 2006Publication date: August 24, 2006Applicant: SHARP KABUSHIKI KAISHAInventors: Yoshihiro Ueta, Takayuki Yuasa, Atsushi Ogawa, Yuhzoh Tsuda, Masahiro Araki
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Patent number: 7064357Abstract: A nitride compound semiconductor light emitting device includes: a GaN substrate having a crystal orientation which is tilted away from a <0001> direction by an angle which is equal to or greater than about 0.05° and which is equal to or less than about 2°, and a semiconductor multilayer structure formed on the GaN substrate, wherein the semiconductor multilayer structure includes: an acceptor doping layer containing a nitride compound semiconductor; and an active layer including a light emitting region.Type: GrantFiled: January 12, 2001Date of Patent: June 20, 2006Assignee: Sharp Kabushiki KaishaInventors: Yoshihiro Ueta, Takayuki Yuasa, Atsushi Ogawa, Yuhzoh Tsuda, Masahiro Araki
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Publication number: 20060065197Abstract: A vapor deposition apparatus of the present invention has a substrate holder having a substrate holding surface for holding a substrate thereon, and a flow channel for supplying a source gas onto the substrate. The flow channel has an upper wall and a lower wall. An aperture portion is provided in the lower wall of the flow channel. The substrate holding surface of the substrate holder fits in the aperture portion while forming a space between the substrate holding surface and the aperture portion. A means for reducing leakage of gas through the space between the aperture portion and the substrate holder is provided. With this structure, since a means for reducing leakage of gas through the space between the aperture portion and the substrate holder is provided, the conductance with respect to outflow of gas increases, which in turn reduces variations in the amount of outflow gas. This results in high yield production of nitride semiconductor devices with a long life and high light-emission efficiency.Type: ApplicationFiled: September 27, 2005Publication date: March 30, 2006Inventors: Eiji Yamada, Takayuki Yuasa, Masahiro Araki, Nakao Akutsu
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Patent number: 7015058Abstract: A nitride semiconductor laser device using a group III nitride semiconductor also as a substrate offers excellent operation characteristics and a long laser oscillation life. In a layered structure of a group III nitride semiconductor formed on a GaN substrate, a laser optical waveguide region is formed elsewhere than right above a dislocation-concentrated region extending so as to vertically penetrate the substrate, and electrodes are formed on the top surface of the layered structure and on the bottom surface of the substrate elsewhere than right above or below the dislocation-concentrated region. In a portion of the top surface of the layered structure and in a portion of the bottom surface of the substrate right above and below the dislocation-concentrated region, dielectric layers may be formed to prevent the electrodes from making contact with those regions.Type: GrantFiled: August 13, 2004Date of Patent: March 21, 2006Assignees: Sharp Kabushiki Kaisha, Sumitomo Electric Industries, Ltd.Inventors: Kunihiro Takatani, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
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Publication number: 20060057824Abstract: The present invention relates to an apparatus for producing a nitride semiconductor by crystal-growing the nitride semiconductor on a substrate by diffusing a gas containing a source gas of group III element and a source gas of group V element. The gas is diffused in parallel with the substrate and from upstream to downstream. The apparatus has the substrate housed in the apparatus and a flow channel for allowing the gas to flow in the flow channel. The apparatus also has a plurality of protrusions provided on an inner wall of the flow channel. A partition for causing the source gas of group III element and the source gas of group V element to be introduced separately into the flow channel is provided on the upstream portion of the flow channel and in a horizontal direction. The protrusions are formed on the upper and lower surfaces of the partition. With this structure, the source gas of group III element and the source gas of group V element are more uniformly mixed before the source gases are supplied.Type: ApplicationFiled: September 9, 2005Publication date: March 16, 2006Inventors: Masahiro Araki, Eiji Yamada, Takayuki Yuasa, Yuhzoh Tsuda, Nakao Akutsu
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Patent number: 6984841Abstract: The nitride semiconductor light emitting device includes a nitride semiconductor underlayer (102) grown on a surface of a nitride semiconductor substrate or a surface of a nitride semiconductor substrate layer laminated over a base substrate of other than a nitride semiconductor, and a light emitting device structure having a light emitting layer (106) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer (103–105) and a p type layer (107–110) over the nitride semiconductor underlayer. It includes a depression (D) not flattened on a surface of the light emitting device structure even after growth of the light emitting device structure.Type: GrantFiled: January 30, 2002Date of Patent: January 10, 2006Assignee: Sharp Kabushiki KaishaInventors: Yuhzoh Tsuda, Daisuke Hanaoka, Takayuki Yuasa, Shigetoshi Ito, Mototaka Taneya
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Patent number: 6924512Abstract: A nitride semiconductor light emitting device includes an emission layer (106) having a multiple quantum well structure where a plurality of quantum well layers and a plurality of barrier layers are alternately stacked. The quantum well layer is formed of XN1-x-y-zAsxPySbz (0?x?0.15, 0?y?0.2, 0?z?0.05, x+y+z>0) where X represents one or more kinds of group III elements. The barrier layer is formed of a nitride semiconductor layer containing at least Al.Type: GrantFiled: May 7, 2001Date of Patent: August 2, 2005Assignee: Sharp Kabushiki KaishaInventors: Yuhzoh Tsuda, Takayuki Yuasa, Shigetoshi Ito
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Publication number: 20050141577Abstract: A nitride semiconductor laser device has a nitride semiconductor substrate that includes a dislocation-concentrated region 102 and a wide low-dislocation region and that has the top surface thereof slanted at an angle in the range of 0.3° to 0.7° relative to the C plane and a nitride semiconductor layer laid on top thereof. The nitride semiconductor layer has a depression immediately above the dislocation-concentrated region, and has, in a region thereof other than the depression, a high-quality quantum well active layer with good flatness and without cracks, a layer that, as is grown, readily exhibits p-type conductivity, and a stripe-shaped laser light waveguide region. The laser light waveguide region is formed above the low-dislocation region. This helps realize a nitride semiconductor laser device that offers a longer life.Type: ApplicationFiled: April 26, 2004Publication date: June 30, 2005Applicants: Sharp Kabushiki Kaisha, Sumitomo Electric Industries, Ltd.Inventors: Yoshihiro Ueta, Teruyoshi Takakura, Takeshi Kamikawa, Yuhzoh Tsuda, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
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Patent number: 6891201Abstract: A nitride semiconductor light emitting device includes a processed substrate (101a) including a groove and a hill formed on a main surface of a nitride semiconductor substrate, a nitride semiconductor underlayer (102) covering the groove and the hill of the processed substrate, and a light emitting device structure having a light emitting layer (106) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer (103-105) and a p type layer (107-110) over the nitride semiconductor underlayer. A current-constricting portion of the light emitting device structure is formed above a region more than 1 ?m away from the center of the groove in the width direction and more than 1 ?m away from the center of the hill in the width direction.Type: GrantFiled: January 9, 2002Date of Patent: May 10, 2005Assignee: Sharp Kabushiki KaishaInventors: Yuhzoh Tsuda, Takayuki Yuasa, Shigetoshi Ito, Mototaka Taneya, Yukio Yamasaki
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Publication number: 20050048682Abstract: A nitride semiconductor laser device using a group III nitride semiconductor also as a substrate offers excellent operation characteristics and a long laser oscillation life. In a layered structure of a group III nitride semiconductor formed on a GaN substrate, a laser optical waveguide region is formed elsewhere than right above a dislocation-concentrated region extending so as to vertically penetrate the substrate, and electrodes are formed on the top surface of the layered structure and on the bottom surface of the substrate elsewhere than right above or below the dislocation-concentrated region. In a portion of the top surface of the layered structure and in a portion of the bottom surface of the substrate right above and below the dislocation-concentrated region, dielectric layers may be formed to prevent the electrodes from making contact with those regions.Type: ApplicationFiled: August 13, 2004Publication date: March 3, 2005Applicants: SHARP KABUSHIKI KAISHA, SUMITOMO ELECTRIC INDUSTRIES, LTD.Inventors: Kunihiro Takatani, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
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Publication number: 20050042787Abstract: A nitride semiconductor laser device with a reduction in internal crystal defects and an alleviation in stress, and a semiconductor optical apparatus comprising this nitride semiconductor laser device. First, a growth suppressing film against GaN crystal growth is formed on the surface of an n-type GaN substrate equipped with alternate stripes of dislocation concentrated regions showing a high density of crystal defects and low-dislocation regions so as to coat the dislocation concentrate regions. Next, the n-type GaN substrate coated with the growth suppressing film is overlaid with a nitride semiconductor layer by the epitaxial growth of GaN crystals. Further, the growth suppressing film is removed to adjust the lateral distance between a laser waveguide region and the closest dislocation concentrated region to 40 ?m or more.Type: ApplicationFiled: October 28, 2002Publication date: February 24, 2005Inventors: Shigetoshi Ito, Takayuki Yuasa, Yoshihiro Ueta, Mototaka Taneya, Zenpei Tani, Kensaku Motoki
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Patent number: 6812496Abstract: A nitride semiconductor laser device using a group III nitride semiconductor also as a substrate offers excellent operation characteristics and a long laser oscillation life. In a layered structure of a group III nitride semiconductor formed on a GaN substrate, a laser optical waveguide region is formed elsewhere than right above a dislocation-concentrated region extending so as to vertically penetrate the substrate, and electrodes are formed on the top surface of the layered structure and on the bottom surface of the substrate elsewhere than right above or below the dislocation-concentrated region. In a portion of the top surface of the layered structure and in a portion of the bottom surface of the substrate right above and below the dislocation-concentrated region, dielectric layers may be formed to prevent the electrodes from making contact with those regions.Type: GrantFiled: December 31, 2002Date of Patent: November 2, 2004Assignees: Sharp Kabushiki Kaisha, Sumitomo Electric Industries, Ltd.Inventors: Kunihiro Takatani, Shigetoshi Ito, Takayuki Yuasa, Mototaka Taneya, Kensaku Motoki
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Publication number: 20040113141Abstract: A nitride semiconductor light emitting device includes a processed substrate (101a) including a groove and a hill formed on a main surface of a nitride semiconductor substrate, a nitride semiconductor underlayer (102) covering the groove and the hill of the processed substrate, and a light emitting device structure having a light emitting layer (106) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer (103-105) and a p type layer (107-110) over the nitride semiconductor underlayer. A current-constricting portion of the light emitting device structure is formed above a region more than 1 &mgr;m away from the center of the groove in the width direction and more than 1 &mgr;m away from the center of the hill in the width direction.Type: ApplicationFiled: July 14, 2003Publication date: June 17, 2004Inventors: Yuhzoh Isuda, Takayuki Yuasa, Shigetoshi Ito, Mototaka Taneya, Yukio Yamasaki
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Publication number: 20040041156Abstract: The nitride semiconductor light emitting device includes a nitride semiconductor underlayer (102) grown on a surface of a nitride semiconductor substrate or a surface of a nitride semiconductor substrate layer laminated over a base substrate of other than a nitride semiconductor, and a light emitting device structure having a light emitting layer (106) including a quantum well layer or a quantum well layer and a barrier layer in contact with the quantum well layer between an n type layer (103-105) and a p type layer (107-110) over the nitride semiconductor underlayer. It includes a depression (D) not flattened on a surface of the light emitting device structure even after growth of the light emitting device structure.Type: ApplicationFiled: August 14, 2003Publication date: March 4, 2004Inventors: Yuhzoh Tsuda, Daisuke Hanaoka, Takayuki Yuasa, Shigetoshi Ito, Motokata Taneya
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Patent number: 6685773Abstract: A crystal growth method for growing a nitride semiconductor crystal on a sapphire substrate in a vapor phase, includes the steps of: providing a sapphire substrate having a substrate orientation inclined by about 0.05° to about 0.2° from a <0001>orientation; and allowing a nitride semiconductor crystal to grow on the surface of the sapphire substrate.Type: GrantFiled: May 3, 2001Date of Patent: February 3, 2004Assignee: Sharp Kabushiki KaishaInventors: Yoshihiro Ueta, Takayuki Yuasa