Patents by Inventor Yoshitaka NAKATSU

Yoshitaka NAKATSU 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: 11881684
    Abstract: A semiconductor laser element includes: an n-side semiconductor layer formed of a nitride semiconductor; an active layer disposed on or above the n-side semiconductor layer and formed of a nitride semiconductor; a p-side semiconductor layer disposed on the active layer, formed of a nitride semiconductor, and including: an undoped first part disposed in contact with an upper face of the active layer and comprising at least one semiconductor layer, an electron barrier layer disposed in contact with an upper face of the first part, containing a p-type impurity, and having a band gap energy that is larger than a band gap energy of the first part, and a second part disposed in contact with the upper face of the electron barrier layer and comprising at least one p-type semiconductor layer containing a p-type impurity; and a p-electrode disposed in contact with the upper face of the second part.
    Type: Grant
    Filed: March 3, 2022
    Date of Patent: January 23, 2024
    Assignee: NICHIA CORPORATION
    Inventor: Yoshitaka Nakatsu
  • Publication number: 20220271510
    Abstract: A semiconductor laser element includes: an n-side semiconductor layer formed of a nitride semiconductor; an active layer disposed on or above the n-side semiconductor layer and formed of a nitride semiconductor; a p-side semiconductor layer disposed on the active layer, formed of a nitride semiconductor, and including: an undoped first part disposed in contact with an upper face of the active layer and comprising at least one semiconductor layer, an electron barrier layer disposed in contact with an upper face of the first part, containing a p-type impurity, and having a band gap energy that is larger than a band gap energy of the first part, and a second part disposed in contact with the upper face of the electron barrier layer and comprising at least one p-type semiconductor layer containing a p-type impurity; and a p-electrode disposed in contact with the upper face of the second part.
    Type: Application
    Filed: March 3, 2022
    Publication date: August 25, 2022
    Applicant: NICHIA CORPORATION
    Inventor: Yoshitaka NAKATSU
  • Patent number: 11296485
    Abstract: A semiconductor laser element includes an n-side semiconductor layer, an active layer, and a p-side semiconductor layer. A least a portion of the p-side semiconductor layer forms a ridge projecting upward. The p-side semiconductor layer includes an undoped first part, an electron barrier layer containing a p-type impurity and having a larger band gap energy than the first part, and a second part having at least one p-type semiconductor layer. The first part includes an undoped p-side composition graded layer in which a band gap energy increases towards the electron barrier layer, and an undoped p-side intermediate layer disposed on or above the p-side composition graded layer. A lower end of the ridge is positioned at the p-side intermediate layer.
    Type: Grant
    Filed: January 14, 2020
    Date of Patent: April 5, 2022
    Assignee: NICHIA CORPORATION
    Inventor: Yoshitaka Nakatsu
  • Publication number: 20200235550
    Abstract: A semiconductor laser element includes an n-side semiconductor layer, an active layer, and a p-side semiconductor layer. A least a portion of the p-side semiconductor layer forms a ridge projecting upward. The p-side semiconductor layer includes an undoped first part, an electron barrier layer containing a p-type impurity and having a larger band gap energy than the first part, and a second part having at least one p-type semiconductor layer. The first part includes an undoped p-side composition graded layer in which a band gap energy increases towards the electron barrier layer, and an undoped p-side intermediate layer disposed on or above the p-side composition graded layer. A lower end of the ridge is positioned at the p-side intermediate layer.
    Type: Application
    Filed: January 14, 2020
    Publication date: July 23, 2020
    Applicant: NICHIA CORPORATION
    Inventor: Yoshitaka NAKATSU
  • Patent number: 9774169
    Abstract: A semiconductor laser element includes an n-side semiconductor layer, an active layer, and a p-side semiconductor layer, layered upward in this order, each being made of a nitride semiconductor. The active layer includes one or more well layers, and an n-side barrier layer located lower than the one or more well layers. The n-side semiconductor layer includes a composition-graded layer located in contact with the n-side barrier layer. The composition-graded layer has a band-gap energy that decreases toward an upper side of the composition-graded layer, with a band-gap energy of the upper side being smaller than a band-gap energy of the n-side barrier layer. The composition-graded layer has an n-type dopant concentration greater than 5×1017/cm3 and less than or equal to 2×1018/cm3. The n-side barrier layer has an n-type dopant concentration greater than that of the composition-graded layer and a thickness smaller than that of the composition graded layer.
    Type: Grant
    Filed: November 29, 2016
    Date of Patent: September 26, 2017
    Assignee: NICHIA CORPORATION
    Inventor: Yoshitaka Nakatsu
  • Publication number: 20170155230
    Abstract: A semiconductor laser element includes an n-side semiconductor layer, an active layer, and a p-side semiconductor layer, layered upward in this order, each being made of a nitride semiconductor. The active layer includes one or more well layers, and an n-side barrier layer located lower than the one or more well layers. The n-side semiconductor layer includes a composition-graded layer located in contact with the n-side barrier layer. The composition-graded layer has a band-gap energy that decreases toward an upper side of the composition-graded layer, with a band-gap energy of the upper side being smaller than a band-gap energy of the n-side barrier layer. The composition-graded layer has an n-type dopant concentration greater than 5×1017/cm3 and less than or equal to 2×1018/cm3. The n-side barrier layer has an n-type dopant concentration greater than that of the composition-graded layer and a thickness smaller than that of the composition graded layer.
    Type: Application
    Filed: November 29, 2016
    Publication date: June 1, 2017
    Applicant: NICHIA CORPORATION
    Inventor: Yoshitaka NAKATSU
  • Patent number: 9519207
    Abstract: Provided is a wavelength converting device having excellent optical output. The wavelength converting device includes a substrate and a wavelength converting member disposed on the substrate. The wavelength converting member includes a fluorescent material powder and a binder binding the fluorescent material powder. An upper surface of the wavelength converting member serves as a light emitting surface which includes upper surfaces of the fluorescent material powder and an upper surface of the binder. The binder has first recesses formed adjacent to the fluorescent material powder in the upper surface of the binder.
    Type: Grant
    Filed: December 26, 2012
    Date of Patent: December 13, 2016
    Assignee: NICHIA CORPORATION
    Inventors: Yoshitaka Nakatsu, Takafumi Sugiyama
  • Publication number: 20130163225
    Abstract: Provided is a wavelength converting device having excellent optical output. The wavelength converting device includes a substrate and a wavelength converting member disposed on the substrate. The wavelength converting member includes a fluorescent material powder and a binder binding the fluorescent material powder. An upper surface of the wavelength converting member serves as a light emitting surface which includes upper surfaces of the fluorescent material powder and an upper surface of the binder. The binder has first recesses formed adjacent to the fluorescent material powder in the upper surface of the binder.
    Type: Application
    Filed: December 26, 2012
    Publication date: June 27, 2013
    Applicant: Nichia Corporation
    Inventors: Yoshitaka NAKATSU, Takafumi Sugiyama