Patents by Inventor Takashi Tsunekawa

Takashi Tsunekawa 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: 7179667
    Abstract: As shown in FIG. 1(a), substrate 1 having a growth plane having a concavo-convex surface is used. When GaN group crystal is vapor phase grown using this substrate, the concavo-convex shape suppresses growth in the lateral direction and promotes growth in the C axis direction, thereby affording a base surface capable of forming a facet plane. Thus, as shown in FIG. 1(b), a crystal having a facet plane is grown in a convex part, and a crystal is also grown in a concave part. When the crystal growth is continued, the films grown from the convex part and the concave part are joined in time to cover a concavo-convex surface and become flat as shown in FIG. 1(c). In this case, an area having a low a dislocation density is formed in the upper part of the convex part where facet plane was formed, and the prepared film has high quality.
    Type: Grant
    Filed: September 17, 2001
    Date of Patent: February 20, 2007
    Assignee: Mitsubishi Cable Industries, Ltd.
    Inventors: Hiroaki Okagawa, Kazuyuki Tadatomo, Yoichiro Ouchi, Takashi Tsunekawa
  • Patent number: 7053420
    Abstract: Concaves and convexes 1a are formed by processing the surface layer of a first layer 1, and second layer 2 having a different refractive index from the first layer is grown while burying the concaves and convexes (or first crystal 10 is grown as concaves and convexes on crystal layer S to be the base of the growth, and second crystal 20 is grown, which has a different refractive index from the first crystal). After forming these concavo-convex refractive index interfaces 1a (10a), an element structure, wherein semiconductor crystal layers containing a light-emitting layer A are laminated, is formed. As a result, the light in the lateral direction, which is generated in the light-emitting layer changes its direction by an influence of the concavo-convex refractive index interface and heads toward the outside.
    Type: Grant
    Filed: March 20, 2002
    Date of Patent: May 30, 2006
    Assignee: Mitsubishi Cable Industries, Ltd.
    Inventors: Kazuyuki Tadatomo, Hiroaki Okagawa, Yoichiro Ouchi, Takashi Tsunekawa
  • Publication number: 20040113166
    Abstract: Concaves and convexes 1a are formed by processing the surface layer of a first layer 1, and second layer 2 having a different refractive index from the first layer is grown while burying the concaves and convexes (or first crystal 10 is grown as concaves and convexes on crystal layer S to be the base of the growth, and second crystal 20 is grown, which has a different refractive index from the first crystal). After forming these concavo-convex refractive index interfaces 1a (10a), an element structure, wherein semiconductor crystal layers containing a light-emitting layer A are laminated, is formed. As a result, the light in the lateral direction, which is generated in the light-emitting layer changes its direction by an influence of the concavo-convex refractive index interface and heads toward the outside.
    Type: Application
    Filed: December 9, 2003
    Publication date: June 17, 2004
    Inventors: Kazuyuki Tadatomo, Hiroaki Okagawa, Yoichiro Ouchi, Takashi Tsunekawa
  • Publication number: 20040056258
    Abstract: As an embodiment of the element structure, a structure including, from the downside, a sapphire C-plane substrate 1, a GaN buffer layer 11 grown at a low temperature, an un-doped GaN layer 12, an Si-doped n-GaN contact layer 21, a light emitting layer 3 of a multiple quantum well structure (MQW) having plural well layers, an Mg-doped p-AlGaN cladding layer 22, and an Mg-doped p-GaN contact layer 23 is mentioned. The above-mentioned light emitting layer 3 is capable of multi-wavelength light emission by a multi-layer structure emitting light having at least two peaks in an emission spectrum, which is achieved by, for example, forming plural groups having different band gaps of the well layer. As a result, a light having plural wavelengths is emitted from a single light emitting layer, and by simply injecting current into a pair of p-type and n-type electrodes, a light emitting element emitting multicolor light, particularly white light, can be provided.
    Type: Application
    Filed: October 9, 2003
    Publication date: March 25, 2004
    Inventors: Kazuyuki Tadatomo, Hiroaki Okagawa, Yoichiro Ouchi, Takashi Tsunekawa
  • Publication number: 20040048471
    Abstract: As shown in FIG. 1(a), substrate 1 having a growth plane having a concavo-convex surface is used. When GaN group crystal is vapor phase grown using this substrate, the concavo-convex shape suppresses growth in the lateral direction and promotes growth in the C axis direction, thereby affording a base surface capable of forming a facet plane. Thus, as shown in FIG. 1(b), a crystal having a facet plane is grown in a convex part, and a crystal is also grown in a concave part. When the crystal growth is continued, the films grown from the convex part and the concave part are joined in time to cover a concavo-convex surface and become flat as shown in FIG. 1(c). In this case, an area having a low a dislocation density is formed in the upper part of the convex part where facet plane was formed, and the prepared film has high quality.
    Type: Application
    Filed: April 17, 2003
    Publication date: March 11, 2004
    Inventors: Hiroaki Okagawa, Kazuyuki Tadatomo, Yoichiro Ouchi, Takashi Tsunekawa