Patents by Inventor Isamu Akasaki
Isamu Akasaki 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: 5905276Abstract: Disclosed is a light-emitting semiconductor device which comprises an N-layer of N-type nitrogen-Group III compound semiconductor satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0 and x=y=0, a P-layer of P-type nitrogen-Group III compound semiconductor satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0 and x=y=0 and a Zn doped semi-insulating I-layer of nitrogen-Group III compound semiconductor satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0 and x=y=0. The semi-insulating I-layer has a 20 to 3000 .ANG. thickness and can emit light in the range of 485 to 490 nm. By employing the I-layer, the light-emitting diode as a whole can emit light in the range of 450 to 480 nm.Type: GrantFiled: November 6, 1997Date of Patent: May 18, 1999Assignees: Isamu Akasaki, Hiroshi Amano, Toyoda Gosei Co., Ltd.Inventors: Katsuhide Manabe, Masahiro Kotaki, Hisaki Kato, Michinari Sassa, Isamu Akasaki, Hiroshi Amano
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Patent number: 5889806Abstract: A laser diode using Group III nitride compound semiconductor consists of In.sub.0.2 Ga.sub.0.8 N/GaN SQW active layer 5, a pair of GaN guide layers 41 and 62, sandwiching the active layer with wider forbidden band than the active layer, and a pair of Al.sub.0.08 Ga.sub.0.92 N cladding layer 4 and 71, sandwiching a pair of the guide layers, and the LD confines carriers and light separately. Al.sub.0.15 Ga.sub.0.75 N stopper layers 41 and 62 with wider forbidden band than the guide layers are formed in some portion of each of the guide layers 41 and 62 in parallel to the active layer. As a result, carriers are confined in the active layer and the laser output of the LD is improved.Type: GrantFiled: August 8, 1997Date of Patent: March 30, 1999Assignee: Toyoda Gosei Co., Ltd.Inventors: Seiji Nagai, Shiro Yamasaki, Masayoshi Koike, Kazuyoshi Tomita, Tetsu Kachi, Isamu Akasaki, Hiroshi Amano
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Patent number: 5862167Abstract: A light-emitting diode or laser diode is provided which uses a Group III nitride compound semiconductor satisfying the formula (Al.sub.x Ga.sub.1-x).sub.y In.sub.1-y N, inclusive of 0.ltoreq.x.ltoreq.1, and 0.ltoreq.y.ltoreq.1. A double hetero-junction structure is provided which sandwiches an active layer between layers having wider band gaps than the active layer. The diode has a multi-layer structure which has either a reflecting layer to reflect emission light or a reflection inhibiting layer. The emission light of the diode exits the diode in a direction perpendicular to the double hetero-junction structure. Light emitted in a direction opposite to the light outlet is reflected by the reflecting film toward the direction of the light outlet. Further, the reflection inhibiting film, disposed at or near the light outlet, helps the release of exiting light by minimizing or preventing reflection. As a result, light can be efficiently emitted by the light-generating diode.Type: GrantFiled: May 27, 1997Date of Patent: January 19, 1999Assignees: Toyoda Gosei Co., Ltd., Research Development Corporation of Japan, Isamu Akasaki, Hiroshi AmanoInventors: Michinari Sassa, Norikatsu Koide, Shiro Yamazaki, Junichi Umezaki, Naoki Shibata, Masayoshi Koike, Isamu Akasaki, Hiroshi Amano
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Patent number: 5846844Abstract: A nitrogen-group III compound semiconductor satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0 and x=y=0, and a method for producing the same comprising the steps of forming a zinc oxide (ZnO) intermediate layer on a sapphire substrate, forming a nitrogen-group III semiconductor layer satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0 and x=y=0 on the intermediate ZnO layer, and separating the intermediate ZnO layer by wet etching with an etching liquid only for the ZnO layer.Type: GrantFiled: February 7, 1996Date of Patent: December 8, 1998Assignees: Toyoda Gosei Co., Ltd., Isamu Akasaki, Hiroshi Amano, Kazumasa HiramatsuInventors: Isamu Akasaki, Hiroshi Amano, Kazumasa Hiramatsu, Theeradetch Detchprohm
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Patent number: 5834326Abstract: A process for producing a semiconductor emitting device of group III nitride semiconductor having a crystal layer (Al.sub.x Ga.sub.1-x).sub.1-y In.sub.y N (0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1) includes; a step of forming at least one pn-junction or pin-junction and a crystal layer (Al.sub.x Ga.sub.1-x).sub.1-y In.sub.y N (0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1) to which a group II element is added; and a step of forming electrodes on the crystal layer. The process further includes an electric-field-assisted annealing treatment in which the pn-junction or pin-junction is heated to the predetermined temperature range while forming and maintaining an electric field across the pn-junction or pin-junction for at least partial time period of the predetermined temperature range via the electrodes.Type: GrantFiled: December 11, 1996Date of Patent: November 10, 1998Assignee: Pioneer Electronic CorporationInventors: Mamoru Miyachi, Toshiyuki Tanaka, Yoshinori Kimura, Hirokazu Takahashi, Hitoshi Sato, Atsushi Watanabe, Hiroyuki Ota, Isamu Akasaki, Hiroshi Amano
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Patent number: 5825789Abstract: A method for forming a resonator in a semiconductor laser device comprises the steps of; filling with a resin a gap surrounding the side surfaces of the waveguide for a resonator other than the end-surface to be polished; polishing the end-surface and the resin surrounding it; forming a predetermined optical coating on the polished end-surface and the resin in the state of the laser waveguide and the electrode being embedded; and removing the embedding resin. Both the bending of polished end-surfaces and the entering of the thin film into the side surface of the laser waveguide is prevented so that a high smooth end-surface of mirror coating for resonator is achieved. Furthermore, any crystals are used for a substrate carrying a semiconductor laser structure with a resonator even if that crystal is of non-cleavage, according to that method.Type: GrantFiled: December 22, 1995Date of Patent: October 20, 1998Assignee: Pioneer Electric CorporationInventors: Yoshiaki Watanabe, Satoshi Miyaguchi, Hiroshi Amano, Isamu Akasaki
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Patent number: 5733796Abstract: A light-emitting semiconductor device using a gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N) having an i.sub.L -layer of insulating gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N, inclusive of x=0) containing a low concentration of p-type impurities. An i.sub.H -layer of insulating gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N, inclusive of x=0) containing a high concentration of p-type impurities is adjacent to the i.sub.L -layer. An n-layer of n-type gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N, inclusive of x=0) of low carrier concentration is adjacent to the i.sub.L -layer. An n.sup.+ -layer of n-type gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N, inclusive of x=0) of high carrier concentration doped with n-type impurities is adjacent to the n-layer.Type: GrantFiled: November 9, 1995Date of Patent: March 31, 1998Assignees: Toyoda Gosei Co., Ltd., Kabushiki Kaisha Toyota Chuo Kenkyusho, Nagoya University, Research Development Corporation of JapanInventors: Katsuhide Manabe, Akira Mabuchi, Hisaki Kato, Michinari Sassa, Norikatsu Koide, Shiro Yamazaki, Masafumi Hashimoto, Isamu Akasaki
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Patent number: 5620557Abstract: A method of manufacturing two sapphireless layers (3a, 3b) at one time made of Group III nitride compound semiconductor satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0, and x=y=0, and a LED (10) utilizing one of the semiconductor layers (3a, 3b) as a substrate (3) includes the steps of forming two zinc oxide (ZnO) intermediate layers (2a, 2b) on each side of a sapphire substrate (1), forming two Group III nitride compound semiconductor layers (3a, 3b) satisfying the formula Al.sub.x Ga.sub.y In.sub.1-x-y N, inclusive of x=0, y=0, and x=y=0, each laminated on each of the intermediate ZnO layers (2a, 2b), and separating the intermediate ZnO layers (2a, 2b) from the sapphire substrate (1) by etching with an etching liquid only for the ZnO layers (2a, 2b).Type: GrantFiled: June 26, 1995Date of Patent: April 15, 1997Assignee: Toyoda Gosei Co., Ltd.Inventors: Katsuhide Manabe, Masayoshi Koike, Hisaki Kato, Norikatsu Koide, Isamu Akasaki, Hiroshi Amano
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Patent number: 5604763Abstract: An improved laser diode is made of a gallium nitride compound semiconductor ((Al.sub.x Ga.sub.1-x).sub.y In.sub.1-y N; 0.ltoreq.x.ltoreq.1; 0.ltoreq.x.ltoreq.1) with a double heterojunction structure having the active layer held between layers having a greater band gap. The laser diode comprises mirror surfaces formed by cleaving the multi-layered coating and the sapphire substrate in directions parallel to <0001> (c axis) of the sapphire substrate. The intermediate zinc oxide (ZnO) layer is selectively removed by wet etching with a ZnO-selective liquid etchant so as to form gaps between the sapphire substrate and the bottom-most sub-layer of the semiconductor laser element layer. The semiconductor laser element layer is cleaved with the aid of the gaps, and the resulting planes of cleavage are used as the mirror surfaces of the laser cavity.Type: GrantFiled: April 19, 1995Date of Patent: February 18, 1997Assignees: Toyoda Gosei Co., Ltd., Research Development of Japan, Isamu Akasaki, Hiroshi AmanoInventors: Hisaki Kato, Norikatsu Koide, Masayoshi Koike, Isamu Akasaki, Hiroshi Amano
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Patent number: 5583879Abstract: A gallium nitride group compound semiconductor laser diode (10) satisfying the formula (Al.sub.x Ga.sub.1-x).sub.y In.sub.1-y N, inclusive of 0.ltoreq.x.ltoreq.1 and 0.ltoreq.y.ltoreq.1 comprises by a double hetero-junction structure sandwiching an active layer (5) between layers (4, 6) having wider band gaps than the active layer (5). The active layer (5) may comprise magnesium (Mg) doped p-type conductive gallium nitride group compound semiconductor satisfying the formula (Al.sub.x Ga.sub.1-x).sub.y In.sub.1-y N, inclusive of 0.ltoreq.x.ltoreq.1 and 0.ltoreq.y.ltoreq.1 . In another embodiment, the active layer (5) is doped with silicon (Si).Type: GrantFiled: April 19, 1995Date of Patent: December 10, 1996Assignees: Toyoda Gosei Co., Ltd., Research Development, Isamu Akasaki, Hiroshi AmanoInventors: Shiro Yamazaki, Norikatsu Koide, Katsuhide Manabe, Isamu Akasaki, Hiroshi Amano
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Patent number: 5496766Abstract: Disclosure is a process for producing a luminous element of III-group nitride semiconductor having a crystal layer (Al.sub.x Ga.sub.1-x).sub.1-y In.sub.y N (0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1) to which a II-group element is added, comprising the steps of forming a crystal layer (Al.sub.x Ga.sub.1-x).sub.1-y In.sub.y N (0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1) to which a II-group element is added; irradiating a low energy electron beam onto a topmost surface of the crystal layer to reform only the crystal layer; forming a thin film for absorbing optical energy on the topmost surface of the crystal layer; and pulse-heating the thin film for absorbing optical energy by heating means to reform only the crystal layer, thereby to produce a bluish green, blue or UV light emitting diode or a semiconductor laser diode with a high precision color purity.Type: GrantFiled: March 28, 1995Date of Patent: March 5, 1996Assignee: Pioneer Electronic CorporationInventors: Hiroshi Amano, Isamu Akasaki, Toshiyuki Tanaka, Teruo Tohma, Katsuhide Manabe
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Patent number: 5389571Abstract: Disclosed are a gallium nitride type semiconductor device that has a single crystal of (Ga.sub.1-x Al.sub.x).sub.1-y In.sub.y N, which suppresses the occurrence of crystal defects and thus has very high crystallization and considerably excellent flatness, and a method of fabricating the same. The gallium nitride type semiconductor device comprises a silicon substrate, an intermediate layer consisting of a compound containing at least aluminum and nitrogen and formed on the silicon substrate, and a crystal layer of (Ga.sub.1-x Al.sub.x).sub.1-y In.sub.y N (0.ltoreq.x.gtoreq.1, 0.ltoreq.y.ltoreq.1, excluding the case of x=1 and y=0). According to the method of fabricating a gallium nitride base semiconductor device, a silicon single crystal substrate is kept at a temperature of 400.degree. to 1300.degree. C.Type: GrantFiled: April 16, 1993Date of Patent: February 14, 1995Assignees: Hiroshi Amano, Isamu Akasaki, Pioneer Electronic Corporation, Toyoda Gosei Co., Ltd.Inventors: Tetsuya Takeuchi, Hiroshi Amano, Isamu Akasaki, Atsushi Watanabe, Katsuhide Manabe
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Patent number: 5370738Abstract: A compound semiconductor vapor phase epitaxial device comprises a cylindrical reactor vessel, a plurality of flow channels disposed in the reactor vessel, a crystal substrate disposed in one of the flow channels, a plurality of gas supply pipes for respectively supplying gas containing element of compound to be grown on the crystal substrate and at least one slit or linearly arranged fine holes communicating adjacent two flow channels so as to extend in a direction normal to a direction of the gas flow to form a laminate layer flow consisting of two or more than two gases at an upstream portion of location of the crystal substrate.Type: GrantFiled: February 3, 1993Date of Patent: December 6, 1994Assignees: Pioneer Electronic Corporation, Hiroshi Amano, Isamu AkasakiInventors: Atsushi Watanabe, Hiroshi Amano, Kazumasa Hiramatsu, Isamu Akasaki
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Patent number: 5281830Abstract: There are disclosed two types of gallium nitride LED having the pn junction. An LED of gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N, where 0.ltoreq.x<1) comprises an n-layer; a p-layer which exhibits p-type conduction upon doping with p-type impurities and irradiation with electron rays, the p-layer joining to the n-layer; a first electrode for the n-layer so as to join to the n-layer, passing through a hole formed in the p-layer which extends from the p-layer to the n-layer; and a second electrode for the p-layer which is formed in a region which is separated by a groove formed in the p-layer so as to extend from the upper surface of the p-layer to said n-layer.Type: GrantFiled: October 24, 1991Date of Patent: January 25, 1994Assignees: Toyoda Gosei Co., Ltd., Nagoya University, Research Development Corporation of JapanInventors: Masahiro Kotaki, Isamu Akasaki, Hiroshi Amano
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Patent number: 5278433Abstract: Disclosed herein are (1) a light-emitting semiconductor device that uses a gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N) in which the n-layer of n-type gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N) is of double-layer structure including an n-layer of low carrier concentration and an n.sup.+ -layer of high carrier concentration, the former being adjacent to the i-layer of insulating gallium nitride compound semiconductor (Al.sub.x Ga.sub.1-x N); (2) a light-emitting semiconductor device of similar structure as above in which the i-layer is of double-layer structure including an i.sub.L -layer of low impurity concentration containing p-type impurities in comparatively low concentration and an i.sub.Type: GrantFiled: August 7, 1992Date of Patent: January 11, 1994Assignees: Toyoda Gosei Co., Ltd., Kabushiki Kaisha Toyota Chuo Kenkyusho, Nagoya University, Research Development Corporation of JapanInventors: Katsuhide Manabe, Akira Mabuchi, Hisaki Kato, Michinari Sassa, Norikatsu Koide, Shiro Yamazaki, Masafumi Hashimoto, Isamu Akasaki
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Patent number: 5247533Abstract: A gallium nitride group compound semiconductor laser diode includes at least one pn junction layer disposed between an n-type layer and a p-type layer. The n-type layer is formed from a gallium nitride group compound semiconductor material defined by the composition equation (Al.sub.x Ga.sub.1-x).sub.y In.sub.1-y N (where 0.ltoreq.x.ltoreq.1 and 0.ltoreq.y.ltoreq.1). The p-type layer, doped with an acceptor impurity, is obtained by electron beam irradiating a gallium nitride group compound semiconductor material defined by the composition equation (Al.sub.x' Ga.sub.1-x').sub.y' In.sub.1-y' N (where 0.ltoreq.x'.ltoreq.1, 0.ltoreq.y'.ltoreq.1, x=x' or x.noteq.x', and, y=y' or y.noteq.y'). The improved gallium nitride group semiconductor laser diode of the present invention is found to emit light in the visible short wavelength spectrum of light which includes the blue, violet and ultraviolet regions.Type: GrantFiled: December 26, 1991Date of Patent: September 21, 1993Assignees: Toyoda Gosei Co., Ltd., Isamu Akasaki, Hiroshi AmanoInventors: Nobuo Okazaki, Katsuhide Manabe, Isamu Akasaki, Hiroshi Amano
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Patent number: 5239188Abstract: Disclosed are a gallium nitride type semiconductor device that has a single crystal of (Ga.sub.l-x Al.sub.x).sub.l-y In.sub.y N, which suppresses the occurrence of crystal defects and thus has very high crystallization and considerably excellent flatness, and a method of fabricating the same. The gallium nitride type semiconductor device comprises a silicon substrate, an intermediate layer consisting of a compound containing at least aluminum and nitrogen and formed on the silicon substrate, and a crystal layer of (Ga.sub.l-x Al.sub.x).sub.l-y In.sub.y N (0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, excluding the case of x=1 and y=0). According to the method of fabricating a gallium nitride base semiconductor device, a silicon single crystal substrate is kept at a temperature of 400 to 1300.degree. C.Type: GrantFiled: November 4, 1992Date of Patent: August 24, 1993Assignees: Hiroshi Amano, Isamu Akasaki, Pioneer Electronic Corporation, Toyoda Gosei Co., Ltd.Inventors: Tetsuya Takeuchi, Hiroshi Amano, Isamu Akasaki, Atsushi Watanabe, Katsuhide Manabe
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Patent number: 5218216Abstract: A thin film of SiO.sub.2 is patterned on an N layer consisting of N-type Al.sub.x Ga.sub.1-x N (inclusive of x=0). Next, I-type Al.sub.x Ga.sub.1-x N (inclusive of x=0) is selectively grown and the portion on the N layer grows into an I-layer consisting an active layer of a light emitting diode, and that on the SiO.sub.2 thin film grows into a conductive layer. Electrodes are formed on the I-layer and conductive layer to constitute the light emitting diode. Also, on the surface a ({1120}) of a sapphire substrate, a buffer layer consisting of aluminum nitride is formed, onto which a gallium nitride group semiconductor is formed.Type: GrantFiled: December 20, 1991Date of Patent: June 8, 1993Assignees: Toyoda Gosei Co., Ltd., Nagoya UniversityInventors: Katsuhide Manabe, Nobuo Okazaki, Isamu Akasaki, Kazumasa Hiramatsu, Hiroshi Amano
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Patent number: 5122845Abstract: A substrate for producing a gallium nitride compound-semiconductor (Al.su Ga.sub.1-x N; X=0 inclusive) device in vapor phase on a sapphire substrate using gaseous organometallic compound, and a also blue light emitting diode produced by using the substrate. The buffer layer comprising aluminium nitride (AlN) and having a crystal structure where microcrystal or polycrystal is mixed in amorphous state, is formed on the sapphire substrate. The buffer layer is formed at a growth temperature of 380.degree. to 800.degree. C. to have a thickness of 100 to 500 .ANG.. Further, on the buffer layer is formed the layer of gallium nitride compound-semiconductor (Al.sub.x Ga.sub.1-x N; X=0 inclusive). The layer of gallium nitride compound-semiconductor (Al.sub.x Ga.sub.1-x N; X=0 inclusive) comprising at least two layers having different conductive types and being sequentially layered on the buffer layer, functions as a light emitting layer.Type: GrantFiled: February 26, 1990Date of Patent: June 16, 1992Assignees: Toyoda Gosei Co., Ltd., Nagoya University and Research Development Corporation of JapanInventors: Katsuhide Manabe, Hisaki Kato, Isamu Akasaki, Kazumasa Hiramatsu, Hiroshi Amano
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Patent number: 4855249Abstract: In organometallic vapor phase hetero-epitaxial processes for growing Al.sub.x Ga.sub.1-x N films on a sapphire substrate, the substrate is subjected to a preheat treatment of brief duration, such as less than 2 minutes, at relatively low temperatures in an atmosphere comprising Al-containing organometallic compound, NH.sub.3 and H.sub.2 gases, prior to the hetero epitaxial growth of Al.sub.x Ga.sub.1-x N films. Thus, single crystalline Al.sub.x Ga.sub.1-x N layers of high uniformity and high quality having smooth, flat surfaces are provided. Multi-layers grown according to the process of the invention are free from cracks and have preferable UV or blue light emission properties.Type: GrantFiled: March 16, 1988Date of Patent: August 8, 1989Assignee: Nagoya UniversityInventors: Isamu Akasaki, Nobuhiko Sawaki