Patents by Inventor Kazuhiko Itaya

Kazuhiko Itaya 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).

  • Patent number: 5321712
    Abstract: A semiconductor light-emitting element includes a semiconductor substrate of a first conductivity type, a lower cladding layer formed on the semiconductor substrate and constituted by an InGaAlP-based compound of the first conductivity type, an active layer formed on the lower cladding layer, and constituted by a material selected from the group consisting of GaAs, GaAlAs, and InGaAs, and an upper cladding layer formed on the active layer, and constituted by the InGaAlP-based compound of a second conductivity type, wherein the InGaAlP-based compound is represented by a formula In.sub.y (Ga.sub.1-x Al.sub.x).sub.y P, where x is in the range of 0.3 to 0.7 and y is in the range of 0.45 to 0.55.
    Type: Grant
    Filed: January 29, 1993
    Date of Patent: June 14, 1994
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Kazuhiko Itaya, Koichi Nitta, Genichi Hatakoshi, Yukie Nishikawa, Hideto Sugawara, Mariko Suzuki
  • Patent number: 5305341
    Abstract: According to this invention, in a semiconductor laser, an n-type InGaAlP cladding layer, an InGaP active layer, and a p-type InGaAlP cladding layer are sequentially grown on an n-type GaAs substrate to form a double hetero structure. The active layer is constituted by an ordered structure having regularity in the <111> directions, and the p-type cladding layer is constituted by a disordered structure. Band discontinuity in conduction band between the active layer and the p-type cladding layer is increased to improve the temperature characteristics of the laser.
    Type: Grant
    Filed: February 19, 1992
    Date of Patent: April 19, 1994
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yukie Nishikawa, Koichi Nitta, Genichi Hatakoshi, Masaki Okajima, Minoru Watanabe, Kazuhiko Itaya
  • Patent number: 5282218
    Abstract: A semiconductor laser device for radiating a laser beam from a double heterostructure section in which injected carriers having an energy source of the laser beam are confined consists of a compound semiconductor substrate with a prescribed lattice constant for loading the double heterostructure section, a lattice mismatched active layer with a first lattice constant which is 0.5% to 2.0% larger than the lattice constant of the substrate in the double heterostructure section for radiating the laser beam, a lattice mismatched cladding layer with a second lattice constant which is 0.2% to 2.0% smaller than the lattice constant of the substrate for confining the injected carriers in the active layer, and a cladding layer for confining the injected carriers in the active layer by co-operating with the lattice mismatched cladding layer.
    Type: Grant
    Filed: June 9, 1992
    Date of Patent: January 25, 1994
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masaki Okajima, Koichi Nitta, Genichi Hatakoshi, Yukie Nishikawa, Kazuhiko Itaya
  • Patent number: 5181218
    Abstract: An InGaAlP NAM structure laser is formed with a double-heterostructure section disposed on an n-type GaAs substrate. The double-heterostructure section includes a first cladding layer of n-type InGaAlP, a non-doped InGaP active layer, and a second cladding layer of p-type InGaAlP. An n-type GaAs current-blocking layer having a stripe opening and a p-type GaAs contact layer are sequentially formed on the second cladding layer by MOCVD crystal growth. A low-energy band gap region is defined in a central region of the active layer located immediately below the stripe opening. A high-energy band gap region is defined in a peripheral region of the active layer corresponding to a light output end portion of the laser and located immediately below the current-blocking layer. Therefore, self absorption of an oscillated laser beam at the output end portion can be reduced or prevented.
    Type: Grant
    Filed: November 29, 1990
    Date of Patent: January 19, 1993
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masayuki Ishikawa, Hajime Okuda, Hideo Shiozawa, Kazuhiko Itaya, Yukio Watanabe, Mariko Suzuki, Genichi Hatakoshi
  • Patent number: 5153889
    Abstract: Disclosed is a semiconductor light emitting device, comprising a semiconductor substrate, a double hetero structure portion formed on the front surface of the substrate and consisting of an InGaAlP active layer and lower and upper clad layers having the active layer sandwiched therebetween, a first electrode formed in a part of the surface of the double hetero structure portion, and a second electrode formed on the back surface of the substrate. A current diffusion layer formed of GaAlAs is interposed between the double hetero structure portion and the first electrode, said current diffusion layer having a thickness of 5 to 30 microns and a carrier concentration of 5.times.10.sup.17 cm.sup.-3 to 5.times.10.sup.18 cm.sup.-3.
    Type: Grant
    Filed: August 19, 1991
    Date of Patent: October 6, 1992
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hideto Sugawara, Masayuki Ishikawa, Yoshihiro Kokubun, Yukie Nishikawa, Shigeya Naritsuka, Kazuhiko Itaya, Genichi Hatakoshi, Mariko Suzuki
  • Patent number: 5138404
    Abstract: A semiconductor device for passing electric current between a GaAs semiconductor layer (103) and an InGaAlP semiconductor layer (101) both having the same conductivity type. The device includes a higher carrier density region (102) with the carrier density equal to or more than 5.times.10.sup.17 cm.sup.-3 and thickness in a rannge from 400 .ANG. to 800 .ANG. in at least a part of the InGaAlP layer (101) adjoining the GaAs layer (103). As a result, good ohmic contact is achieved and the semiconductor device has a lower operating voltage and a satisfactory thermal characteristic.
    Type: Grant
    Filed: May 31, 1991
    Date of Patent: August 11, 1992
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masayuki Ishikawa, Kazuhiko Itaya, Genichi Hatakoshi
  • Patent number: 5036521
    Abstract: In a semiconductor laser device, for emitting a laser beam having a wavelength .lambda., an n-type In.sub.0.5 (Ga.sub.1-x Al.sub.x)P first cladding layer is formed on an n-type GaAs substrate. An undoped InGaP active layer is formed on the first cladding layer and a p-type In.sub.0.5 (Ga.sub.1-x Al.sub.x).sub.0.5 P cladding layer is formed on the active layer. A p-type InGaP cap layer is formed on the second cladding layer and an n-type GaAs current restricting layer is formed on the second cladding layer. The aluminum composition ratio x of the cladding layer is 0.7. The active layer has a thickness of 0.06 .mu.m and the cladding layers have the same thickness H of 0.85 .mu.m. The active layer and the cladding layers have refractive indices n.sub.a and n.sub.c which satisfies the following inequalities:0.015.DELTA..sup.1/2 <d/.lambda.<0.028.DELTA..sup.-1/2and.DELTA.=(n.sub.a.sup.2 -n.sub.c.sup.2)/2n.sub.a.sup.2.
    Type: Grant
    Filed: November 21, 1989
    Date of Patent: July 30, 1991
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Genichi Hatakoshi, Kazuhiko Itaya, Shigeya Naritsuka, Masayuki Ishikawa, Hajime Okuda, Hideo Shiozawa, Yukio Watanabe, Yasuo Ohba, Yoshihiro Kokubun, Yutaka Uematsu
  • Patent number: 5023880
    Abstract: A semiconductor laser device including a semiconductor substrate of a first conductivity type, a double hetero structure, including of a lower cladding layer of the first conductivity type, an active layer, and a first upper cladding layer of In.sub.1-w (Ga.sub.1-y Al.sub.y)wp of the second conductivity type formed on the semiconductor substrate, a second upper cladding layer of In.sub.1-w (Ga.sub.1-w Al.sub.z).sub.w P of the second conductivity type partially formed on the first upper cladding layer, a first contact layer of In.sub.1-w (Ga.sub.1-s Al.sub.s).sub.w P (0<s<z.ltoreq.1) of the second conductivity type formed on the second upper cladding layer, and a second contact layer of GaAs of the second conductivity type formed on the first upper clad layer and the first contact layer. The value of y in In.sub.1-w (Ga.sub.1-y Al.sub.y).sub.w P which constitutes the first upper cladding layer, and the value of z in In.sub.1-w (Ga.sub.1-z Al.sub.z).sub.
    Type: Grant
    Filed: February 12, 1990
    Date of Patent: June 11, 1991
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Mariko Suzuki, Kazuhiko Itaya, Masayuki Ishikawa, Yukio Watanabe, Genichi Hatakoshi
  • Patent number: 4987096
    Abstract: An InGaAlP NAM structure laser is formed with a double-heterostructure section disposed on an n-type GaAs substrate. The double-heterostructure section includes a first cladding layer of n-type InGaAlP, a non-doped InGaP active layer, and a second cladding layer of p-type InGaAlP. An n-type GaAs current-blocking layer having a stripe opening and a p-type GaAs contact layer are sequentially formed on the second cladding layer by MOCVD crystal growth. A low-energy band gap region is defined in a central region of the active layer located immediately below the stripe opening. A high-energy band gap region is defined in a peripheral region of the active layer corresponding to a light output end portion of the laser and located immediately below the current-blocking layer. Therefore, self absorption of an oscillated laser beam at the output end portion can be reduced or prevented.
    Type: Grant
    Filed: December 13, 1989
    Date of Patent: January 22, 1991
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masayuki Ishikawa, Hajime Okuda, Hideo Shiozawa, Kazuhiko Itaya, Yukio Watanabe, Mariko Suzuki, Genichi Hatakoshi
  • Patent number: 4893313
    Abstract: In a semiconductor laser device, for emitting a laser beam having a wavelength .lambda., an n-type In.sub.0.5 (Ga.sub.1-x Al.sub.x)P first cladding layer is formed on an n-type GaAs substrate. An undoped InGaP active layer is formed on the first cladding layer and a p-type In.sub.0.5 (Ga.sub.1-x Al.sub.x).sub.0.5 P cladding layer is formed on the active layer. A p-type InGaP cap layer is formed on the second cladding layer and an n-type GaAs current restricting layer is formed on the second cladding layer. The aluminum composition ratio x of the cladding layer is 0.7. The active layer has a thickness of 0.06 .mu.m and the cladding layers have the same thickness H of 0.85 .mu.m. The active layer and the cladding layers have refractive indices n.sub.a and n.sub.c which satisfies the following inequalities:0.015.DELTA..sup.1/2 <d/.lambda.<0.028.DELTA..sup.-1/2and.DELTA.=(n.sub.a.sup.2 -n.sub.c.sup.2)/2n.sub.a.sup.
    Type: Grant
    Filed: March 14, 1989
    Date of Patent: January 9, 1990
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Genichi Hatakoshi, Kazuhiko Itaya, Shigeya Naritsuka, Masayuki Ishikawa, Hajime Okuda, Hideo Shiozawa, Yukio Watanabe, Yasuo Ohba, Yoshihiro Kokubun, Yutaka Uematsu