Patents by Inventor Takeharu Asano

Takeharu Asano 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).

  • Publication number: 20030045103
    Abstract: When GaN or other nitride III-V compound semiconductor layers are grown on a substrate such as a sapphire substrate, thickness x of the substrate relative to thickness y of the nitride III-V compound semiconductor layers is controlled to satisfy 0<y/x≦0.011 and x≧450 &mgr;m. Alternatively, if the maximum dimension of the substrate is D (cm), its warpage H is in the range of 0<H≦70×10−4 (cm), and Z=y/x, D is controlled to satisfy the relation 0<D<(2/CZ)cos−1(1-HCZ), where C (cm−1) is the proportionality constant when the radius of curvature of the substrate &rgr; (cm) is expressed as 1/&rgr;=CZ.
    Type: Application
    Filed: August 27, 2002
    Publication date: March 6, 2003
    Inventors: Yasuhiko Suzuki, Takeharu Asano, Motonobu Takeya, Osamu Goto, Shinro Ikeda, Katsuyoshi Shibuya
  • Publication number: 20030020087
    Abstract: Provided is a nitride semiconductor having a larger low-defective region on a surface thereof, a semiconductor device using the nitride semiconductor, a method of manufacturing a nitride semiconductor capable of easily reducing surface defects in a step of forming a layer through lateral growth, and a method of manufacturing a semiconductor device manufactured by the use of the nitride semiconductor. A seed crystal portion is formed into stripes on a substrate with a buffer layer sandwiched therebetween. Then, a crystal is grown from the seed crystal portion in two steps of growth conditions to form a nitride semiconductor layer. In a first step, a low temperature growth portion having a trapezoidal-shaped cross section in a layer thickness direction is formed at a growth temperature of 1030° C., and in a second step, lateral growth predominantly takes place at a growth temperature of 1070° C. Then, a high temperature growth potion is formed between the low temperature growth portions.
    Type: Application
    Filed: April 24, 2002
    Publication date: January 30, 2003
    Inventors: Osamu Goto, Takeharu Asano, Motonobu Takeya, Katsunori Yanashima
  • Patent number: 6509579
    Abstract: To provide a semiconductor device capable of preventing the bowing of the substrate, and having a semiconductor layer of a III-V group compound of a nitride system with excellent crystallinity. The semiconductor layer of the III-V group compound of the nitride system whose thickness is equal to or less than 8 &mgr;m, is provided onto a substrate made of sapphire. This reduces the bowing of the substrate due to differences in a thermal expansion coefficient and a lattice constant between the substrate and the semiconductor layer of the III-V group compound of the nitride system. An n-side contact layer forming the semiconductor layer of the III-V group of the nitride system has partially a lateral growth region made by growing in a lateral direction from a crystalline part of a seed crystal layer. In the lateral growth region, dislocation density restricts low, therefore, regions corresponding to the lateral growth region of each layer formed onto the n-side contact layer has excellent crystallinity.
    Type: Grant
    Filed: January 16, 2001
    Date of Patent: January 21, 2003
    Assignee: Sony Corporation
    Inventors: Motonobu Takeya, Katsunori Yanashima, Masao Ikeda, Takeharu Asano, Shinro Ikeda, Tomonori Hino, Katsuyoshi Shibuya
  • Publication number: 20020153528
    Abstract: A GaN compound semiconductor laser includes an AlGaN buried layer which buries opposite sides of a ridge stripe portion formed on a p-type AlGaN cladding layer. The AlGaN buried layer is made by first patterning an upper part of the p-type AlGaN cladding layer and a p-type GaN contact layer into a ridge stripe configuration by using a SiO2 film as an etching mask, then growing the AlGaN buried layer non-selectively on the entire substrate surface to bury both sides of the ridge stripe portion under the existence of the SiO2 film on the ridge stripe portion, and thereafter selectively removing the AlGaN buried layer from above the ridge stripe portion by etching using the SiO2 film as an etching stop layer. Thus, the GaN compound semiconductor laser is stabilized in the transverse mode, intensified in output power, and improved in lifetime.
    Type: Application
    Filed: June 17, 2002
    Publication date: October 24, 2002
    Inventors: Takashi Yamaguchi, Toshimasa Kobayashi, Satoru Kijima, Takashi Kobayashi, Tsunenori Asatsuma, Takeharu Asano, Tomonori Hino
  • Publication number: 20020064195
    Abstract: A semiconductor laser, a semiconductor device and a nitride series III-V group compound substrate capable of obtaining a crystal growth layer with less fluctuation of the crystallographic axes and capable of improving the device characteristics, as well as a manufacturing method therefor are provided. The semiconductor laser comprises, on one surface of a substrate used for growing, a plurality of spaced apart seed crystal layers and an n-side contact layer having a lateral growing region which is grown on the basis of the plurality of seed crystal layers. The seed crystal layer is formed in that a product of width w1 (unit: &mgr;m) at the boundary thereof relative to the n-side contact layer along the arranging direction A and a thickness t1 (unit: &mgr;m) along the direction of laminating the n-side contact layer is 15 or less.
    Type: Application
    Filed: June 5, 2001
    Publication date: May 30, 2002
    Inventors: Motonobu Takeya, Katsunori Yanashima, Takeharu Asano, Osamu Goto, Shinro Ikeda, Katsuyoshi Shibuya, Tomonori Hino, Satoru Kijima, Masao Ikeda
  • Publication number: 20010035534
    Abstract: To provide a semiconductor device capable of preventing the bowing of the substrate, and having a semiconductor layer of a III-V group compound of a nitride system with excellent crystallinity.
    Type: Application
    Filed: January 16, 2001
    Publication date: November 1, 2001
    Inventors: Motonobu Takeya, Katsunori Yanashima, Masao Ikeda, Takeharu Asano, Shinro Ikeda, Tomonori Hino, Katsuyoshi Shibuya
  • Publication number: 20010025989
    Abstract: To provide a semiconductor device capable of enhancing crystallinity of a semiconductor of a III-V group compound of a nitride system formed on a sapphire substrate and to provide a method of manufacturing the same.
    Type: Application
    Filed: January 12, 2001
    Publication date: October 4, 2001
    Inventors: Katsuyoshi Shibuya, Takeharu Asano, Satoru Kijima, Katsunori Yanashima, Motonobu Takeya, Masao Ikeda, Tomonori Hino, Takashi Yamaguchi, Shinro Ikeda, Osamu Goto
  • Patent number: 5433170
    Abstract: A metal-organic chemical vapor-phase deposition process for fabricating a layer of a Group II-VI compound semiconductor using an organometallic compound based on bis(cyclopentadienyl)magnesium having a vapor pressure in the range of from 1.3.times.10 Pa to 1.3.times.10.sup.2 Pa at a temperature of 330.degree. K. The present invention also provides a light-emitting device which is fabricated by means of the metal-organic vapor-phase deposition process above. The process according to the present invention provides a magnesium-containing compound semiconductor layer having an accurately controlled composition, and it readily enables the fabrication of a compound semiconductor layer having a grated structure.
    Type: Grant
    Filed: November 4, 1994
    Date of Patent: July 18, 1995
    Assignee: Sony Corporation
    Inventors: Atsushi Toda, Takeharu Asano