Patents by Inventor Mitsuhiro Shigeta

Mitsuhiro Shigeta 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: 5481273
    Abstract: A large-scale liquid crystal display comprises a signal transmission channel which includes an inductance in the line direction and in the column direction for transmitting a display signal of the large-scale display to a pixel without delay. The signal transmission channel is arranged so that the display signal is propagated in the form of solitary waves or solitons whereby an LCD can be driven with a uniform display and a high contrast.
    Type: Grant
    Filed: July 12, 1994
    Date of Patent: January 2, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Mitsuhiro Shigeta, Keisaku Nonomura, Kazuyuki Kishimoto
  • Patent number: 5455883
    Abstract: An optical wave guide, an optical input device, fabrication methods thereof, and a liquid crystal display apparatus using the optical wave guide and optical input device are disclosed. The optical wave guide includes: a core region having a refractive index n.sub.c through which an optical signal is transmitted; and a cladding layer in which low refractive index layers having a refractive index n.sub.1 and high refractive index layers having a refractive index n.sub.h are alternately deposited. A side face of the core region is covered with the cladding layer, and the refractive indices satisfy conditions of n.sub.1 <n.sub.h, and n.sub.1 <n.sub.c. The optical input device includes: a transparent substrate; the optical wave guide formed in the transparent substrate; an optical input portion; and a plurality of optical output portions for connecting a side face of the optical wave guide to a surface of the transparent substrate.
    Type: Grant
    Filed: April 7, 1993
    Date of Patent: October 3, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Mitsuhiro Shigeta, Keisaku Nonomura
  • Patent number: 5387804
    Abstract: A light emitting diode is disclosed which comprises at least one heterojunction composed of silicon carbide (SIC) and semiconductor materials selected from the group consisting of gallium nitride (GAN), aluminum nitride (AlN), and aluminum gallium nitride (Ga.sub.x Al.sub.1-x N, 0<x<1).
    Type: Grant
    Filed: September 14, 1992
    Date of Patent: February 7, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Akira Suzuki, Katsuki Furukawa, Mitsuhiro Shigeta, Yoshihisa Fujii
  • Patent number: 5381251
    Abstract: An optical switch element for selectively transmitting or shielding light from a first optical wave guide to a second optical wave guide is disclosed. The optical switch element includes a first optical switch portion and a second optical switch portion. The first optical switch portion includes: a part of said first optical wave guide; a first liquid crystal layer optically connected to said part of said first optical wave guide; a first part of said second optical wave guide optically connected to said first liquid crystal layer; and first voltage applying means for applying voltage to said first liquid crystal layer to change a refractive index of said first liquid crystal layer.
    Type: Grant
    Filed: April 7, 1993
    Date of Patent: January 10, 1995
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Keisaku Nonomura, Mitsuhiro Shigeta
  • Patent number: 5319220
    Abstract: A silicon carbide semiconductor device is provided which includes at least one heterojunction composed of two different polytypes of silicon carbide. The two polytypes of silicon carbide in the heterojunction include a .beta.-type silicon carbide layer having an .alpha.-type silicon carbide layer disposed thereon.
    Type: Grant
    Filed: June 8, 1992
    Date of Patent: June 7, 1994
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Akira Suzuki, Katsuki Furukawa, Mitsuhiro Shigeta, Yoshihisa Fujii, Atsuko Ogura
  • Patent number: 5279701
    Abstract: A method for the growth of silicon carbide single crystals is disclosed which includes the step of growing silicon carbide single crystals on a silicon single-crystal substrate. The silicon single-crystal substrate has growth areas with a crystal orientation inclined by an angle .theta. from the [100] direction toward at least one of the [011] and [011] directions and with a lateral dimension d taken along the direction of such inclination toward the [011] or [011] direction. The angle .theta. is set to be in the range of zero to tan.sup.-1 (.sqroot.2/8) degrees (with the proviso that the angle .theta. is not equal to tan.sup.-1 (.sqroot.2/2) degrees). The lateral dimension d is set to be in the range of 0.1 to 100 .mu.m. In this method, the silicon carbide single crystals are grown to a thickness t approximately equal to or greater than (.sqroot.2+tan.theta.)d/.vertline.1-.sqroot.2tan.theta..vertline., so that these silicon carbide single crystals are substantially free of defects such as stacking faults.
    Type: Grant
    Filed: August 24, 1992
    Date of Patent: January 18, 1994
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Mitsuhiro Shigeta, Akira Suzuki, Katsuki Furukawa, Yoshihisa Fujii
  • Patent number: 5216264
    Abstract: A silicon carbide field-effect transistor is disclosed which includes an MOS structure composed successively of a silicon carbide layer, a gate insulator film, and a gate electrode. The field-effect transistor has source and drain regions formed in the silicon carbide layer, between which the MOS structure is disposed, wherein at least one of the source and drain regions is formed by the use of a Schottky contact on the silicon carbide layer.
    Type: Grant
    Filed: September 16, 1991
    Date of Patent: June 1, 1993
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yoshihisa Fujii, Akira Suzuki, Katsuki Furukawa, Mitsuhiro Shigeta
  • Patent number: 5184199
    Abstract: A silicon carbide semiconductor device is disclosed which includes a semiconductor substrate and a silicon carbide single-crystal layer formed above the substrate, the silicon carbide single-crystal layer having a device active region. The silicon carbide semiconductor device further includes an aluminum nitride single-crystal layer which is disposed between the silicon carbide single-crystal layer and the substrate. The aluminum nitride single-crystal layer functions as an electrically insulating layer by which the silicon carbide signale-crystal layer is isolated electrically from the substrate.
    Type: Grant
    Filed: June 5, 1990
    Date of Patent: February 2, 1993
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yoshihisa Fujii, Akira Suzuki, Katsuki Furukawa, Mitsuhiro Shigeta
  • Patent number: 5135885
    Abstract: A method of manufacturing a semiconductor device comprises the steps of (i) forming a SiC monocrystal layer over the entire surface of a semiconductor substrate; (ii) forming a boron ion implanted layer, which is substantially a thin film, by implanting a specified amount of boron ions in the surface region of the SiC monocrystal layer; and (iii) forming a high resistance SiC monocrystal layer of a thin film by subjecting the boron ion implanted layer to heat treatment; whereby the high resistance SiC monocrystal layer can be function at least as an electric insulating layer.
    Type: Grant
    Filed: March 27, 1990
    Date of Patent: August 4, 1992
    Assignee: Sharp Corporation
    Inventors: Katsuki Furukawa, Yoshihisa Fujii, Mitsuhiro Shigeta, Akira Suzuki
  • Patent number: 5063421
    Abstract: A silicon carbide light emitting diode having a pn junction is disclosed which comprises a semiconductor substrate, a first silicon carbide single-crystal layer of one conductivity formed on the substrate, and a second silicon carbide single-crystal layer of the opposite conductivity formed on the first silicon carbide layer, the first and second silicon carbide layers constituting the pn junction, wherein at least one of the first and second silicon carbide layers contains a tetravalent transition element as a luminescent center.
    Type: Grant
    Filed: August 7, 1989
    Date of Patent: November 5, 1991
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Akira Suzuki, Katsuki Furukawa, Mitsuhiro Shigeta, Yoshihisa Fujii
  • Patent number: 5049950
    Abstract: A MIS structure is provided which uses a photoconductive amorphous silicon carbide layer as an insulator layer in the MIS structure. The insulator layer is disposed on an n-type layer of single crystal silicon carbide and a translucent metal layer is disposed thereon. The metal layer is biased with a negative voltage so that the capacitance between the metal layer and the semiconductor layer changes in response to whether on the metal layer is illuminated with light.
    Type: Grant
    Filed: August 9, 1990
    Date of Patent: September 17, 1991
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yoshihisa Fujii, Mitsuhiro Shigeta, Katsuki Furukawa, Kenji Nakanishi, Atsuko Ogura
  • Patent number: 4990994
    Abstract: An electrode structure for a silicon carbide single-crystal semiconductor in which the surface of the silicon carbide single-crystal is laminated with a metal layer of titanium, aluminum, chromium or molybdenum, or with the metal layer and an electrically conductive protective layer formed over the metal layer to provide an ohmic electrode.
    Type: Grant
    Filed: September 5, 1989
    Date of Patent: February 5, 1991
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Katsuki Furukawa, Akira Suzuki, Mitsuhiro Shigeta, Atsuko Uemoto
  • Patent number: 4897149
    Abstract: A single-crystal substrate of silicon carbide comprising a single-crystal substrate member of a material other than .alpha.-SiC, and a single-crystal layer of .alpha.-SiC formed over the substrate member with a ground layer provided between the substrate member and the single-crystal layer, the ground layer comprising a single-crystal layer of nitride of AlN, GaN or Al.sub.x Ga.sub.1-x N (0<x<1) having a hexagonal crystal structure or a crystal layer of the same structure made of a mixture of SiC and at least one of the nitrides; and a method for fabricating the same.
    Type: Grant
    Filed: June 10, 1986
    Date of Patent: January 30, 1990
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Akira Suzuki, Katsuki Furukawa, Mitsuhiro Shigeta
  • Patent number: 4865659
    Abstract: A heteroepitaxial growth method comprising growing a semiconductor single-crystal film on a semiconductor single-crystal substrate with a lattice constant different from that of the semiconductor single-crystal film by chemical vapor deposition, the epitaxial orientation of the semiconductor single-crystal film being inclined at a certain angle with respect to the semiconductor single-crystal substrate.
    Type: Grant
    Filed: November 24, 1987
    Date of Patent: September 12, 1989
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Mitsuhiro Shigeta, Akira Suzuki, Katsuki Furukawa, Yoshihisa Fujii, Akitsugu Hatano, Atsuko Uemoto, Kenji Nakanishi