Patents by Inventor Motoyuki Yamamoto
Motoyuki Yamamoto 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: 5408488Abstract: A semiconductor laser device comprising, a first clad layer of the first conductivity type semiconductor crystal deposited on a first electrode layer, an active layer, a second clad layer formed of a semiconductor crystal of a second conductivity type, a current barrier layer having a stripe-like current inlet opening, a second electrode layer formed of a semiconductor crystal of the second conductivity type, and disposed on the current barrier layer and on the electric current inlet opening. A first electrode is formed on the second electrode layer. A second electrode is formed on the bottom surface of the first electrode layer. Between the current barrier layer and the second clad layer is formed a photoelectric current barrier layer formed of a semiconductor crystal of the first conductivity type having a larger band gap than that of the active layer.Type: GrantFiled: July 7, 1994Date of Patent: April 18, 1995Assignee: Kabushiki Kaisha ToshibaInventors: Haruki Kurihara, Motoyuki Yamamoto
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Patent number: 4959839Abstract: A rib waveguide type semiconductor laser including p-type high impurity concentration layer formed between a p-upper cladding layer and p-ohmic layer and having an impurity concentration higher than the impurity concentration of the p-upper cladding layer and p-ohmic layer. The high impurity concentration layer acts to make small a discontinous portion of the valence band between the p-upper cladding layer and p-ohmic layer and change the steep junction to a smoothly inclined junction, thereby lowering the voltage drop across the junction.Type: GrantFiled: July 24, 1989Date of Patent: September 25, 1990Assignee: Kabushiki Kaisha ToshibaInventor: Motoyuki Yamamoto
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Patent number: 4949349Abstract: A double-heterostructure semiconductor laser is disclosed which has a semiconductive substrate of a first conductivity type made of III-V compound semiconductor material, a first semiconductive cladding layer of the first conductivity type disposed above the substrate, an active layer made of a semiconductor film provided on said cladding layer to serve as a light emission layer, and a second semiconductive cladding layer of a second conductivity type provided on the active layer to define a light waveguide channel of the laser. The second cladding layer is made of a compound semiconductor containing indium, phosphorus, and aluminum. A contact layer section is provided on the second cladding layer to cover the light waveguide channel.Type: GrantFiled: December 5, 1988Date of Patent: August 14, 1990Assignee: Kabushiki Kaisha ToshibaInventors: Yasuo Ohba, Niyoko Watanabe, Hideto Sugawara, Masayuki Ishikawa, Yukio Watanabe, Motoyuki Yamamoto
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Patent number: 4910743Abstract: There is disclosed a semiconductor layer which can emit a continuous laser beam in a visible wavelength range. The laser has an n-GaAs substrate. On this substrate, an n-InGaAlP cladding layer, an active layer, and p-InGaAlP cladding layers are sequentially formed, thus forming a double hetero-structure. A mesa-shaped, upper cladding layer is provided, defining a laser beam-guiding channel. A thin p-InGaAlP contact layer and a mesa-shaped, p-GaAs contact layer are formed on the top surface of the upper cladding layer. Two n-type semiconductive, current-blocking layers cover the slanted sides of the upper, mesa-shaped cladding layer and also the contact layer. They are made of the same n-GaAs compound semiconductor material as the substrate.Type: GrantFiled: December 13, 1988Date of Patent: March 20, 1990Assignee: Kabushiki Kaisha ToshibaInventors: Yasuo Ohba, Masayuki Ishikawa, Motoyuki Yamamoto, Yukio Watanabe, Hideto Sugawara
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Patent number: 4855250Abstract: A method of manufacturing a semiconductor light emitting device by forming a compound semiconductor structure with homo- or heterojunction therein having a first p-type compound semiconductor crystal layer at the top of the structure, growing a second p-type compound semiconductor crystal layer on the structure in a reactor, wherein, before the beginning of the crystal growth step, a p-type dopant is caused to flow into the reactor in which the structure is placed. In some embodiments, the flow of the p-type dopant continues after the completion of the crystal growth.Type: GrantFiled: December 28, 1987Date of Patent: August 8, 1989Assignee: Kabushiki Kaisha ToshibaInventors: Motoyuki Yamamoto, Yasuhiko Tsuburai
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Patent number: 4835117Abstract: There is disclosed a semiconductor layer which can emit a continuous laser beam in a visible wavelength range. The laser has an n-GaAs substrate. On this substrate, an n-InGaAlP cladding layer, an active layer, and p-InGaAlP cladding layers are sequentially formed, thus forming a double hetero-structure. A mesa-shaped, upper cladding layer is provided, defining a laser beam-guiding channel. A thin p-InGaAlP contact layer and a mesa-shaped, p-GaAs contact layer are formed on the top surface of the upper cladding layer. Two n-type semiconductive, current-blocking layers cover the slanted sides of the upper, mesa-shaped cladding layer and also the contact layer. They are made of the same n-GaAs compound semiconductor material as the substrate.Type: GrantFiled: September 21, 1988Date of Patent: May 30, 1989Assignee: Kabushiki Kaisha ToshibaInventors: Yasuo Ohba, Masayuki Ishikawa, Motoyuki Yamamoto, Yukio Watanabe, Hideto Sugawara
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Patent number: 4809287Abstract: Disclosed herein is a double-heterostructure semiconductor laser which emits a laser beam in a visible light range at ambient temperature. An active layer serving as a light emission layer is sandwiched between first and second cladding layers. The first cladding layer comprises an n type InAlP, while the second cladding layer comprises a p type InAlP and has a mesa stripe shape having slanted side surfaces so as to define a light waveguide channel of the semiconductor laser. Current-blocking layers are formed to cover the slanted side surfaces of the second cladding layer. The current-blocking layers comprise GaAs which is a III-V group compound semiconductor different from the III-V group compound semiconductor (i.e., InAlP) comprised in the second cladding layer. The composition ratio of aluminum in the second cladding layer is set not to be less than 0.Type: GrantFiled: August 10, 1987Date of Patent: February 28, 1989Assignee: Kabushiki Kaisha ToshibaInventors: Yasuo Ohba, Miyoko Watanabe, Hideto Sugawara, Masayuki Ishikawa, Yukio Watanabe, Motoyuki Yamamoto
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Patent number: 4799228Abstract: A semiconductor laser diode includes two semiconductive cladding layers of different conductivity types, which are stacked on a substrate. An active layer of an undoped semiconductor film is sandwiched between the cladding layers. A channel groove is formed in a current blocking layer and the underlying cladding layer, to be deep enough to cause the current blocking layer to be divided into two parts. A waveguide layer covers the channel groove and the current-blocking layer, to provide a slab-coupled waveguide structure for transverse mode oscillation. The second cladding layer, the current-blocking layer, and the waveguide layer are composed of gallium arsenide containing aluminum.Type: GrantFiled: August 21, 1986Date of Patent: January 17, 1989Assignee: Kabushiki Kaisha ToshibaInventors: Hiroko Nagasaka, Gen-ichi Hatakoshi, Naohiro Shimada, Motoyuki Yamamoto, Masaki Okajima, Yoshio Iizuka, Hatsumi Kawata, Hideaki Kinoshita, Nobuyuki Matsuura
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Patent number: 4792958Abstract: There is disclosed a semiconductor layer which can emit a continuous laser beam in a visible wavelength range. The laser has an n-GaAs substrate. On this substrate, an n-InGaAlP cladding layer, an active layer, and p-InGaAlP cladding layers are sequentially formed, thus forming a double hetero-structure. A mesa-shaped, upper cladding layer is provided, defining a laser beam-guiding channel. A thin p-InGaAlP contact layer and a mesa-shaped, p-GaAs contact layer are formed on the top surface of the upper cladding layer. Two n-type semiconductive, current-blocking layers cover the slanted sides of the upper, mesa-shaped cladding layer and also the contact layer. They are made of the same n-GaAs compound semiconductor material as the substrate.Type: GrantFiled: February 26, 1987Date of Patent: December 20, 1988Assignee: Kabushiki Kaisha ToshibaInventors: Yasuo Ohba, Masayuki Ishikawa, Motoyuki Yamamoto, Yukio Watanabe, Hideto Sugawara