Patents by Inventor Kazuaki Sasaki

Kazuaki Sasaki 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: 6849473
    Abstract: In a semiconductor light-emitting device, on an n-GaAs substrate are stacked an n-GaAs buffer layer, an n-cladding layer, an undoped active layer, a p-cladding layer, a p-intermediate band gap layer and a p-current diffusion layer. Further, a first electrode is formed under the n-GaAs substrate, and a second electrode is formed on the grown-layer side. In this process, a region of the p-intermediate band gap layer just under the second electrode is removed, the p-current diffusion layer is stacked in the removal region on the p-cladding layer, and a junction plane of the p-current diffusion layer and the p-cladding layer becomes high in resistance due to an energy band structure of type II. This semiconductor light-emitting device is capable of reducing ineffective currents with a simple construction and taking out light effectively to outside, thus enhancing the emission intensity.
    Type: Grant
    Filed: September 25, 2002
    Date of Patent: February 1, 2005
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Kazuaki Sasaki, Junichi Nakamura, Shouichi Ohyama
  • Publication number: 20040238830
    Abstract: It is an object of the present invention to provides the light emitting diode having a light emitting part of an AlGaInP type, and having a current diffusion layer which includes In on a light emitting side of the light emitting part, so that the generation of hillocks is effectively inhibited and the brightness of the light emitting diode is increased.
    Type: Application
    Filed: May 24, 2004
    Publication date: December 2, 2004
    Applicant: SHARP KABUSHIKI KAISHA
    Inventors: Kazuaki Sasaki, Junichi Nakamura
  • Publication number: 20040188701
    Abstract: A semiconductor light emitting element of a monolithic structure, including: a first-conductivity-type semiconductor substrate; an active layer formed on the first-conductivity-type semiconductor substrate; a second-conductivity-type clad layer formed on the active layer; and a current diffusion layer formed on the second-conductivity-type clad layer, wherein the active layer is of a first conductivity type.
    Type: Application
    Filed: January 27, 2004
    Publication date: September 30, 2004
    Applicant: SHARP KABUSHIKI KAISHA
    Inventors: Kiyohisa Ohta, Hiroshi Nakatsu, Kazuaki Sasaki, Junichi Nakamura
  • Publication number: 20040142550
    Abstract: A method for producing a III-V group compound semiconductor layer comprises the steps of: forming a first III-V group compound semiconductor layer on a substrate in a reaction chamber; and supplying a III group material gas to the reaction chamber before or after the step of forming the first III-V group compound semiconductor layer to prevent re-evaporation of the III group gas in the reaction chamber.
    Type: Application
    Filed: January 7, 2004
    Publication date: July 22, 2004
    Applicant: SHARP KABUSHIKI KAISHA
    Inventors: Junichi Nakamura, Kazuaki Sasaki
  • Patent number: 6737669
    Abstract: A semiconductor light-emitting device has a lower clad layer, an active layer, a p-type GaP layer and an upper clad layer, which are successively formed on an n-type GaAs substrate. The p-type GaP layer has a higher energy position by 0.10 eV than the upper clad layer in the conduction band, which makes it more difficult to let electrons escape from the active layer. This contributes to increase of the probability of radiative recombination between electrons and holes in the active layer, and thereby, luminance of the semiconductor light-emitting device is improved. The p-type GaP layer is effective in a semiconductor light-emitting device having a short wavelength in particular.
    Type: Grant
    Filed: November 27, 2002
    Date of Patent: May 18, 2004
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junchi Nakamura, Kazuaki Sasaki
  • Publication number: 20040077487
    Abstract: There are provided (asymmetric) complex catalysts comprising metal complexes and Lewis acids as components, the metal complex being of formula (1): 1
    Type: Application
    Filed: September 8, 2003
    Publication date: April 22, 2004
    Inventor: Kazuaki Sasaki
  • Publication number: 20030143161
    Abstract: A medicinal preparation capable of lowering the threshold of cavitation and generating active oxygen species via acoustic cavitation caused by an ultrasound is provided. The preparation, which is to be used in combination with ultrasonic irradiation, comprises a shell within the internal space of which a gas is enclosed and which contains or retains a substance capable of generating active oxygen species upon ultrasonic irradiation of the shell.
    Type: Application
    Filed: July 19, 2002
    Publication date: July 31, 2003
    Inventors: Kenichi Kawabata, Shinichiro Umemura, Kazuaki Sasaki
  • Publication number: 20030111658
    Abstract: A semiconductor light-emitting device has a lower clad layer, an active layer, a p-type GaP layer and an upper clad layer, which are successively formed on an n-type GaAs substrate. The p-type GaP layer has a higher energy position by 0.10 eV than the upper clad layer in the conduction band, which makes it more difficult to let electrons escape from the active layer. This contributes to increase of the probability of radiative recombination between electrons and holes in the active layer, and thereby, luminance of the semiconductor light-emitting device is improved. The p-type GaP layer is effective in a semiconductor light-emitting device having a short wavelength in particular.
    Type: Application
    Filed: November 27, 2002
    Publication date: June 19, 2003
    Applicant: Sharp Kabushiki Kaisha
    Inventors: Junichi Nakamura, Kazuaki Sasaki
  • Patent number: 6572839
    Abstract: A sensitizer for tumor treatment has a structure such that a lipophilic group and a hydrophilic group are bound to one and the same carbon atom in a compound containing a xanthene dye structure. It is important that the lipophilic group and hydrophilic group are bound to one and the same carbon atom; if they are separated from each other, no sufficient effect is obtained. Thus, the sensitizer possesses both lipophilicity and hydrophilicity. This sensitizer has a function of promoting acoustic cavitation and a function of revealing an antitumor effect and is an agent highly accumulable in tumor tissues. Thus, this sensitizer is highly selective for tumor tissues and enables the treatment of malignant tumor using ultrasound.
    Type: Grant
    Filed: March 9, 2001
    Date of Patent: June 3, 2003
    Assignee: Hitachi, Ltd.
    Inventors: Nami Sugita, Kenichi Kawabata, Shinichiro Umemura, Kazuaki Sasaki, Isao Sakata
  • Publication number: 20030020080
    Abstract: In a semiconductor light-emitting device, on an n-GaAs substrate are stacked an n-GaAs buffer layer, an n-cladding layer, an undoped active layer, a p-cladding layer, a p-intermediate band gap layer and a p-current diffusion layer. Further, a first electrode is formed under the n-GaAs substrate, and a second electrode is formed on the grown-layer side. In this process, a region of the p-intermediate band gap layer just under the second electrode is removed, the p-current diffusion layer is stacked in the removal region on the p-cladding layer, and a junction plane of the p-current diffusion layer and the p-cladding layer becomes high in resistance due to an energy band structure of type II. This semiconductor light-emitting device is capable of reducing ineffective currents with a simple construction and taking out light effectively to outside, thus enhancing the emission intensity.
    Type: Application
    Filed: September 25, 2002
    Publication date: January 30, 2003
    Inventors: Kazuaki Sasaki, Junichi Nakamura, Shouichi Ohyama
  • Patent number: 6511428
    Abstract: An ultrasound therapy apparatus delivers focused ultrasound for therapeutical purposes which can be correctly targeted to a target region, and also, a positional shift from the target region under irradiation of ultrasound can be effectively avoided. An ultrasound transducer is inside an applicator with an imaging ultrasonic probe. Another ultrasound transducer monitors a position of a target and a positional shift is inside a catheter which is inserted into a urethral tube. An imaging system drives the ultrasound probe to display an ultrasound tomographic image of a region in the vicinity of a target region. The ultrasound transducer is driven in a pulse-shaped mode at the same frequency as the imaging ultrasound and also at such timing when the imaging ultrasound is reached. As a result, a point-shaped sound source image is superimposed and displayed on an ultrasound tomographic image.
    Type: Grant
    Filed: April 26, 2001
    Date of Patent: January 28, 2003
    Assignees: Hitachi, Ltd., Hitachi Medical Corporation
    Inventors: Takashi Azuma, Kenichi Kawabata, Shinichiro Umemura, Kazuaki Sasaki, Katsuhiro Kuroda, Ryuichi Shinomura, Yuichi Miwa, Kazunari Ishida, Jun Kubota
  • Publication number: 20030018256
    Abstract: Disclosed is a system for detecting whether a tissue of in the vicinity of a focal point region reaches a temperature at which the tissue is altered thermally in an ultrasound thermal coagulation therapy, and for securing an effect of the therapy. The system includes: irradiating means for irradiating an ultrasound for ultrasound therapy; a signal detection unit for detecting bubble generation in a region to be treated; and a control circuit for controlling a continuous insonation time of a therapeutic ultrasound upon receiving information from the signal detection unit.
    Type: Application
    Filed: February 15, 2002
    Publication date: January 23, 2003
    Inventors: Kazuaki Sasaki, Takashi Azuma, Ken-Ichi Kawabata, Shin-Ichiro Umemura
  • Publication number: 20030008430
    Abstract: With use of MOCVD method, there are grown in sequence on an n-type GaAs substrate 11, an n-type lower clad 12, an active layer 13, and a p-type upper cladding layer 14 to constitute a light emitting portion. On top of the light emitting portion, there are grown in sequence a p-type intermediate layer 15 and a p-type current diffusion layer 16 made of AlGaInP semiconductor. The intermediate layer 15 made of AlGaInP semiconductor is provided with a growth rate of 1 &mgr;m/h or less and a lattice match ratio &Dgr;a/a against GaAs of −3.2% or more and −2.5% or less. A V/III ratio of the intermediate layer 15 in growth and a V/III ratio of the current diffusion layer 16 in growth are so set that a number of crystal defects observed on the crystal surface is 20 or less per semiconductor light-emitting device. Thus-fabricated semiconductor light-emitting device is high in intensity and small in power consumption, and enables enhancement of productivity.
    Type: Application
    Filed: July 8, 2002
    Publication date: January 9, 2003
    Applicant: SHARP KABUSHIKI KAISHA
    Inventors: Junichi Nakamura, Kazuaki Sasaki
  • Patent number: 6476421
    Abstract: In a semiconductor light-emitting device, on an n-GaAs substrate are stacked an n-GaAs buffer layer, an n-cladding layer, an undoped active layer, a p-cladding layer, a p-intermediate band gap layer and a p-current diffusion layer. Further, a first electrode is formed under the n-GaAs substrate, and a second electrode is formed on the grown-layer side. In this process, a region of the p-intermediate band gap layer just under the second electrode is removed, the p-current diffusion layer is stacked in the removal region on the p-cladding layer, and a junction plane of the p-current diffusion layer and the p-cladding layer becomes high in resistance due to an energy band structure of type II. This semiconductor light-emitting device is capable of reducing ineffective currents with a simple construction and taking out light effectively to outside, thus enhancing the emission intensity.
    Type: Grant
    Filed: April 20, 2001
    Date of Patent: November 5, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Kazuaki Sasaki, Junichi Nakamura, Shouichi Ohyama
  • Patent number: 6468818
    Abstract: A semiconductor light-emitting device has a light-emitting section comprised of at least a lower clad layer, an active layer and an upper clad layer which are formed on a compound semiconductor substrate and a layer grown on the upper clad layer of the light-emitting section. When growing the current diffusion layer from a crystal interface on the upper clad layer in a lattice mismatching state in which the absolute value of a lattice matching factor &Dgr;a/a is not lower than 0.25% with respect to the upper clad layer at a crystal interface where the crystal composition changes on the upper clad layer of the light-emitting section, the growth rate at least at the start time of growth is made to be 1.0 &mgr;m/h or less.
    Type: Grant
    Filed: January 25, 2000
    Date of Patent: October 22, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junichi Nakamura, Hiroshi Nakatsu, Kazuaki Sasaki
  • Patent number: 6465812
    Abstract: A semiconductor light emitting device of the present invention at least includes: a GaAs substrate whose principal plane is inclined from a (100) plane in a [011] orientation; a first buffer layer of AlxGa1−xAs (0≦x≦1) provided on the principal plane of the GaAs substrate; a second buffer layer of AlyGaxIn1−y−zP (0≦y≦1 and 0≦z≦1) provided on the first buffer layer; a first cladding layer of AlaGatIn1−a−tP (0≦s≦1 and 0≦t≦1) provided on the second buffer layer; an active layer provided on the first cladding layer; and a second cladding layer provided on the active layer, wherein an Al content s of the first cladding layer is larger than an Al content y of the second buffer layer.
    Type: Grant
    Filed: September 27, 2000
    Date of Patent: October 15, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Hiroyuki Hosoba, Hiroshi Nakatsu, Takahisa Kurahashi, Tetsuroh Murakami, Kazuaki Sasaki, Junichi Nakamura
  • Publication number: 20020123645
    Abstract: Disclosed is a method for producing an optically active chrysanthemic acid, which method is characterized by optical resolution of a chrysanthemic acid having a trans isomer ratio of not less than 70% and an optical purity of 2% e.e. to less than 10% e.e. with an optically active organic.
    Type: Application
    Filed: February 27, 2002
    Publication date: September 5, 2002
    Applicant: SUMITOMO CHEMICAL COMPANY, LIMITED
    Inventors: Gohfu Suzukamo, Kazuaki Sasaki
  • Publication number: 20020098606
    Abstract: A semiconductor light-emitting device has a light-emitting section comprised of at least a lower clad layer, an active layer and an upper clad layer which are formed on a compound semiconductor substrate and a layer grown on the upper clad layer of the light-emitting section. When growing the current diffusion layer from a crystal interface on the upper clad layer in a lattice mismatching state in which the absolute value of a lattice matching factor &Dgr;a/a is not lower than 0.25% with respect to the upper clad layer at a crystal interface where the crystal composition changes on the upper clad layer of the light-emitting section, the growth rate at least at the start time of growth is made to be 1.0 &mgr;m/h or less.
    Type: Application
    Filed: January 25, 2000
    Publication date: July 25, 2002
    Inventors: Junichi Nakamura, Hiroshi Nakatsu, Kazuaki Sasaki
  • Patent number: 6399965
    Abstract: There is provided a semiconductor light emitting device having improved adhesion of an electrode by reducing defects in a crystal surface. An n-type AlGaInP lower clad layer 12, an AlGaInP active layer 13, a p-type AlGaInP upper clad layer 14, a p-type AlGaInP intermediate layer 15 whose lattice matching rate &Dgr;a/a with GaAs is −3.3%, a p-type AlGaInP current diffusion layer 16 and a p-type electrode 17 are laminated on an n-type GaAs substrate 11 and an n-type electrode 18 is provided on the n-type GaAs substrate 11. Thus, the number of crystal defects in the crystal surface can be reduced to 20 or less per one LED by setting the value of the lattice matching rate &Dgr;a/a of the intermediate layer 15 to be −3.3%, which is lower than −2.5%. As a result, adhesion of the p-type electrode 17 formed on the current diffusion layer 16 is improved and thereby the yield of LED can be enhanced.
    Type: Grant
    Filed: January 11, 2001
    Date of Patent: June 4, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Junichi Nakamura, Kazuaki Sasaki, Shouichi Ohyama
  • Patent number: 6399409
    Abstract: The semiconductor light emitting element of the present invention includes: a compound semiconductor substrate having a first conductivity type; a light emitting layer; a compound semiconductor interface layer having a second conductivity type and not containing Al; and a current diffusion layer having the second conductivity type and being made of a compound semiconductor not containing Al.
    Type: Grant
    Filed: April 23, 2001
    Date of Patent: June 4, 2002
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Kazuaki Sasaki, Junichi Nakamura