Patents by Inventor Ikuo Niikura

Ikuo Niikura 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: 7964868
    Abstract: Disclosed is a semiconductor light-emitting device wherein a pn junction is formed by forming, as a p-type layer (11), a semiconductor thin film which is composed of a ZnO compound doped with nitrogen on an n-type ZnO bulk single crystal substrate (10) whose resistance is lowered by being doped with donor impurities. It is preferable to form the p-type layer (11) on a zinc atom containing surface of the n-type ZnO bulk single crystal substrate (10).
    Type: Grant
    Filed: September 5, 2006
    Date of Patent: June 21, 2011
    Assignees: Citizen Tohoku Co., Ltd., Incorporated National University Iwate University
    Inventors: Akira Nakagawa, Yasube Kashiwaba, Ikuo Niikura
  • Publication number: 20090267063
    Abstract: Disclosed is a semiconductor light-emitting device wherein a pn junction is formed by forming, as a p-type layer (11), a semiconductor thin film which is composed of a ZnO compound doped with nitrogen on an n-type ZnO bulk single crystal substrate (10) whose resistance is lowered by being doped with donor impurities. It is preferable to form the p-type layer (11) on a zinc atom containing surface of the n-type ZnO bulk single crystal substrate (10).
    Type: Application
    Filed: September 5, 2006
    Publication date: October 29, 2009
    Applicants: CITIZEN TOHOKU CO., LTD., INCORPORATED NATIONAL UNIVERSITY IWATE UNIVERSITY
    Inventors: Akira Nakagawa, Yasube Kashiwaba, Ikuo Niikura
  • Publication number: 20080056984
    Abstract: Provided is a single crystal with a hexagonal wurtzite structure which is useful as a substrate for various devices and has high purity and is uniform. The single crystal with a hexagonal wurtzite structures which is obtained by a crystal growth on at least an m-plane of a columnar seed crystal and represented by AX (A representing an electropositive element and X representing an electronegative element) is characterized in that a variation in the concentration of a metal other than the electropositive element A and having a concentration of 0.1 to 50 ppm is within 100%.
    Type: Application
    Filed: September 21, 2005
    Publication date: March 6, 2008
    Applicants: Tokyo Denpa Co., Ltd., MITSUBISHI CHEMICAL CORPORATION
    Inventors: Kenji Yoshioka, Hiroshi Yoneyama, Katsumi Maeda, Ikuo Niikura, Mitsuru Sato, Masumi Ito, Fumio Orito
  • Publication number: 20060124051
    Abstract: An objective of the present invention is to provide a zinc oxide (ZnO) single crystal whose electroconductivity is excellent and which has a high quality. The invention relates to a zinc oxide single crystal whose concentration of metals other than zinc in the crystal fulfills the following equation: [?cM]/[+cM]?3 wherein M is a metal other than zinc, [?cM] is a concentration of M in a ?c region in the zinc oxide crystal, and [+cM] is a concentration of M in a +c region in the zinc oxide crystal.
    Type: Application
    Filed: September 30, 2005
    Publication date: June 15, 2006
    Applicants: MITSUBISHI CHEMICAL CORPORATION, Tokyo Denpa Co., Ltd.
    Inventors: Kenji Yoshioka, Hiroshi Yoneyama, Katsumi Maeda, Ikuo Niikura, Mitsuru Sato, Masumi Ito