Patents by Inventor Yuji Zhao

Yuji Zhao 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: 11943922
    Abstract: A non-volatile memory includes a plurality of word lines connected to non-volatile memory cells, a plurality of driver lines configured to carry one or more word line voltages, and a plurality of word line switches that selectively connect the driver lines to the word lines. To more efficiently utilize space on the die, the word line switches are arranged in a plurality of three dimensional stacks such that each stack of the plurality of stacks comprises multiple word line switches vertically stacked.
    Type: Grant
    Filed: November 11, 2023
    Date of Patent: March 26, 2024
    Assignee: Western Digital Technologies, Inc.
    Inventors: Guangyuan Li, Qinghua Zhao, Sudarshan Narayanan, Yuji Totoki, Fumiaki Toyama
  • Patent number: 11626483
    Abstract: Fabricating a regrown GaN p-n junction includes depositing a n-GaN layer on a substrate including n+-GaN, etching a surface of the n-GaN layer to yield an etched surface, depositing a p-GaN layer on the etched surface, etching a portion of the n-GaN layer and a portion of the p-GaN layer to yield a mesa opposite the substrate, and passivating a portion of the p-GaN layer around an edge of the mesa. The regrown GaN p-n junction is defined at an interface between the n-GaN layer and the p-GaN layer. The regrown GaN p-n junction includes a substrate, a n-GaN layer on the substrate having an etched surface, a p-GaN layer on the etched surface, a mesa defined by an etched portion of the n-GaN layer and an etched portion of the p-GaN layer, and a passivated portion of the p-GaN layer around an edge of the mesa.
    Type: Grant
    Filed: September 24, 2020
    Date of Patent: April 11, 2023
    Assignee: Arizona Board of Regents on behalf of Arizona State University
    Inventors: Yuji Zhao, Kai Fu, Houqiang Fu
  • Publication number: 20230106300
    Abstract: Fabricating a vertical-channel junction field-effect transistor includes forming an unintentionally doped GaN layer on a bulk GaN layer by metalorganic chemical vapor deposition, forming a Cr/SiO2 hard mask on the unintentionally doped GaN layer, patterning a fin by electron beam lithography, defining the Cr and SiO2 hard masks by reactive ion etching, improving a regrowth surface with inductively coupled plasma etching, removing hard mask residuals, regrowing a p-GaN layer, selectively etching the p-GaN layer, forming gate electrodes by electron beam evaporation, and forming source and drain electrodes by electron beam evaporation. The resulting vertical-channel junction field-effect transistor includes a doped GaN layer, an unintentionally doped GaN layer on the doped GaN layer, and a p-GaN regrowth layer on the unintentionally doped GaN layer. Portions of the p-GaN regrowth layer are separated by a vertical channel of the unintentionally doped GaN layer.
    Type: Application
    Filed: November 4, 2022
    Publication date: April 6, 2023
    Inventors: Yuji Zhao, Chen Yang, Houqiang Fu, Xuanqi Huang, Kai Fu
  • Patent number: 11527573
    Abstract: A switching device including a GaN substrate; an unintentionally doped GaN layer on a first surface of the GaN substrate; a regrown unintentionally doped GaN layer on the unintentionally doped GaN layer; a regrowth interface between the unintentionally doped GaN layer and the regrown unintentionally doped GaN layer; a p-GaN layer on the regrown unintentionally doped GaN layer; a first electrode on the p-GaN layer; and a second electrode on a second surface of the GaN substrate.
    Type: Grant
    Filed: March 29, 2021
    Date of Patent: December 13, 2022
    Assignee: Arizona Board of Regents on behalf of Arizona State University
    Inventors: Kai Fu, Houqiang Fu, Yuji Zhao
  • Patent number: 11495694
    Abstract: Fabricating a vertical-channel junction field-effect transistor includes forming an unintentionally doped GaN layer on a bulk GaN layer by metalorganic chemical vapor deposition, forming a Cr/SiO2 hard mask on the unintentionally doped GaN layer, patterning a fin by electron beam lithography, defining the Cr and SiO2 hard masks by reactive ion etching, improving a regrowth surface with inductively coupled plasma etching, removing hard mask residuals, regrowing a p-GaN layer, selectively etching the p-GaN layer, forming gate electrodes by electron beam evaporation, and forming source and drain electrodes by electron beam evaporation. The resulting vertical-channel junction field-effect transistor includes a doped GaN layer, an unintentionally doped GaN layer on the doped GaN layer, and a p-GaN regrowth layer on the unintentionally doped GaN layer. Portions of the p-GaN regrowth layer are separated by a vertical channel of the unintentionally doped GaN layer.
    Type: Grant
    Filed: July 12, 2021
    Date of Patent: November 8, 2022
    Assignee: Arizona Board of Regents on behalf of Arizona State University
    Inventors: Yuji Zhao, Chen Yang, Houqiang Fu, Xuanqi Huang, Kai Fu
  • Patent number: 11417529
    Abstract: A p-n diode includes a first electrode, a n-GaN layer on the first electrode, a p-GaN layer on the n-GaN layer, and a second electrode on a first portion of the p-GaN layer. A region of the p-GaN layer surrounding the electrode is a passivated region. Treating a GaN power device having a p-GaN layer includes covering a portion of the p-GaN layer with a metal layer, exposing the p-GaN layer to a hydrogen plasma, and thermally annealing the p-GaN layer, thereby passivating a region of the p-GaN layer proximate the metal layer.
    Type: Grant
    Filed: October 16, 2020
    Date of Patent: August 16, 2022
    Assignee: Arizona Board of Regents on behalf of Arizona State University
    Inventors: Yuji Zhao, Houqiang Fu, Kai Fu
  • Publication number: 20220013671
    Abstract: Fabricating a vertical-channel junction field-effect transistor includes forming an unintentionally doped GaN layer on a bulk GaN layer by metalorganic chemical vapor deposition, forming a Cr/SiO2 hard mask on the unintentionally doped GaN layer, patterning a fin by electron beam lithography, defining the Cr and SiO2 hard masks by reactive ion etching, improving a regrowth surface with inductively coupled plasma etching, removing hard mask residuals, regrowing a p-GaN layer, selectively etching the p-GaN layer, forming gate electrodes by electron beam evaporation, and forming source and drain electrodes by electron beam evaporation. The resulting vertical-channel junction field-effect transistor includes a doped GaN layer, an unintentionally doped GaN layer on the doped GaN layer, and a p-GaN regrowth layer on the unintentionally doped GaN layer. Portions of the p-GaN regrowth layer are separated by a vertical channel of the unintentionally doped GaN layer.
    Type: Application
    Filed: July 12, 2021
    Publication date: January 13, 2022
    Inventors: Yuji Zhao, Chen Yang, Houqiang Fu, Xuanqi Huang, Kai Fu
  • Patent number: 11189717
    Abstract: A steep-slope (SS) field effect transistor (FET) including a FET having a source region and a drain region, and a threshold switching device in direct contact with the source region or the drain region of the FET. Fabricating the steep-slope (SS) field effect transistor (FET) includes fabricating an AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) having a source region and a drain region, depositing a first electrode layer directly on the source region or the drain region, depositing a threshold switching layer directly on the first electrode layer, and depositing a second electrode layer directly on the threshold switching layer.
    Type: Grant
    Filed: January 10, 2020
    Date of Patent: November 30, 2021
    Assignee: Arizona Board of Regents on behalf of Arizona State University
    Inventors: Xuanqi Huang, Yuji Zhao, Runchen Fang, Hugh Barnaby
  • Publication number: 20210242281
    Abstract: A switching device including a GaN substrate; an unintentionally doped GaN layer on a first surface of the GaN substrate; a regrown unintentionally doped GaN layer on the unintentionally doped GaN layer; a regrowth interface between the unintentionally doped GaN layer and the regrown unintentionally doped GaN layer; a p-GaN layer on the regrown unintentionally doped GaN layer; a first electrode on the p-GaN layer; and a second electrode on a second surface of the GaN substrate.
    Type: Application
    Filed: March 29, 2021
    Publication date: August 5, 2021
    Inventors: Kai Fu, Houqiang Fu, Yuji Zhao
  • Publication number: 20210202257
    Abstract: A p-n diode includes a first electrode, a n-GaN layer on the first electrode, a p-GaN layer on the n-GaN layer, and a second electrode on a first portion of the p-GaN layer. A region of the p-GaN layer surrounding the electrode is a passivated region. Treating a GaN power device having a p-GaN layer includes covering a portion of the p-GaN layer with a metal layer, exposing the p-GaN layer to a hydrogen plasma, and thermally annealing the p-GaN layer, thereby passivating a region of the p-GaN layer proximate the metal layer.
    Type: Application
    Filed: October 16, 2020
    Publication date: July 1, 2021
    Inventors: Yuji Zhao, Houqiang Fu, Kai Fu
  • Publication number: 20210104603
    Abstract: Fabricating a regrown GaN p-n junction includes depositing a n-GaN layer on a substrate including n+-GaN, etching a surface of the n-GaN layer to yield an etched surface, depositing a p-GaN layer on the etched surface, etching a portion of the n-GaN layer and a portion of the p-GaN layer to yield a mesa opposite the substrate, and passivating a portion of the p-GaN layer around an edge of the mesa. The regrown GaN p-n junction is defined at an interface between the n-GaN layer and the p-GaN layer. The regrown GaN p-n junction includes a substrate, a n-GaN layer on the substrate having an etched surface, a p-GaN layer on the etched surface, a mesa defined by an etched portion of the n-GaN layer and an etched portion of the p-GaN layer, and a passivated portion of the p-GaN layer around an edge of the mesa.
    Type: Application
    Filed: September 24, 2020
    Publication date: April 8, 2021
    Inventors: Yuji Zhao, Kai Fu, Houqiang Fu
  • Patent number: 10964749
    Abstract: A switching device including a GaN substrate; an unintentionally doped GaN layer on a first surface of the GaN substrate; a regrown unintentionally doped GaN layer on the unintentionally doped GaN layer; a regrowth interface between the unintentionally doped GaN layer and the regrown unintentionally doped GaN layer; a p-GaN layer on the regrown unintentionally doped GaN layer; a first electrode on the p-GaN layer; and a second electrode on a second surface of the GaN substrate.
    Type: Grant
    Filed: October 29, 2019
    Date of Patent: March 30, 2021
    Assignee: Arizona Board of Regents on behalf of Arizona State University
    Inventors: Kai Fu, Houqiang Fu, Yuji Zhao
  • Publication number: 20200295214
    Abstract: A pn heterojunction diode includes a p-GaN substrate, a layer of ?-Ga2O3 on a surface of the p-GaN substrate, an n contact disposed on a surface of the ?-Ga2O3 layer opposite the p-GaN substrate, and a p contact disposed on the surface of the p-GaN substrate and proximate the GaN substrate. Fabricating a pn heterojunction diode includes depositing a metal on a first surface of a ?-Ga2O3 wafer to form a first contact on the first surface of the ?-Ga2O3 wafer, adhering the first contact to an adhesive material, thereby exposing a second surface of the ?-Ga2O3 wafer, wherein the second surface is opposite the first surface, exfoliating layers of the ?-Ga2O3 wafer from the second surface to yield an exfoliated surface on the ?-Ga2O3 wafer, and contacting the exfoliated surface with a surface of a p-GaN substrate to yield a stack.
    Type: Application
    Filed: March 13, 2020
    Publication date: September 17, 2020
    Inventors: Jossue Montes, Chen Yang, Houqiang Fu, Jingan Zhou, Yuji Zhao
  • Publication number: 20200287069
    Abstract: A solar cell including a nonpolar m-plane GaN substrate, an n-type III-nitride layer, a III-nitride active region, and a p-type III-nitride layer. In one example, the solar cell includes a nonpolar m-plane GaN substrate, a Si-doped GaN layer, a multiplicity of InGaN/GaN layers, and and a Mg-doped GaN layer. A working temperature range of the solar cell is from room temperature to about 500° C., an external quantum efficiency of the solar cell increases by at least a factor of 2 from room temperature to 500° C., and a temperature coefficient of the solar cell is greater than zero up to 350° C.
    Type: Application
    Filed: March 6, 2020
    Publication date: September 10, 2020
    Inventors: Xuanqi Huang, Yuji Zhao
  • Publication number: 20200227546
    Abstract: A steep-slope (SS) field effect transistor (FET) including a FET having a source region and a drain region, and a threshold switching device in direct contact with the source region or the drain region of the FET. Fabricating the steep-slope (SS) field effect transistor (FET) includes fabricating an AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) having a source region and a drain region, depositing a first electrode layer directly on the source region or the drain region, depositing a threshold switching layer directly on the first electrode layer, and depositing a second electrode layer directly on the threshold switching layer.
    Type: Application
    Filed: January 10, 2020
    Publication date: July 16, 2020
    Inventors: Xuanqi Huang, Yuji Zhao, Runchen Fang, Hugh Barnaby
  • Patent number: 10700218
    Abstract: An AlN Schottky barrier diode device on sapphire substrates is formed using metal organic chemical vapor deposition and demonstrates a kV-level breakdown voltage. The device structure employs a thin n-AlN epilayer as the device active region and thick resistive AlN underlayer as the insulator. At room temperature, the device was characterized by a low turn-on voltage of 1.2 V, a high on/off ratio of ˜105, a low ideality factor of 5.5, and a low reverse leakage current below 1 nA. Due to the ultra-wide bandgap of AlN, the device also exhibited excellent thermal stability over 500 K representing, therefore, a cost-effective route to high performance AlN based Schottky barrier diodes for high power, high voltage and high temperature applications.
    Type: Grant
    Filed: November 1, 2018
    Date of Patent: June 30, 2020
    Assignee: Arizona Board of Regents on behalf of Arizona State University
    Inventors: Yuji Zhao, Houqiang Fu
  • Publication number: 20200144328
    Abstract: A switching device including a GaN substrate; an unintentionally doped GaN layer on a first surface of the GaN substrate; a regrown unintentionally doped GaN layer on the unintentionally doped GaN layer; a regrowth interface between the unintentionally doped GaN layer and the regrown unintentionally doped GaN layer; a p-GaN layer on the regrown unintentionally doped GaN layer; a first electrode on the p-GaN layer; and a second electrode on a second surface of the GaN substrate.
    Type: Application
    Filed: October 29, 2019
    Publication date: May 7, 2020
    Inventors: Kai Fu, Houqiang Fu, Yuji Zhao
  • Publication number: 20190140110
    Abstract: An AlN Schottky barrier diode device on sapphire substrates is formed using metal organic chemical vapor deposition and demonstrates a kV-level breakdown voltage. The device structure employs a thin n-AlN epilayer as the device active region and thick resistive AlN underlayer as the insulator. At room temperature, the device was characterized by a low turn-on voltage of 1.2 V, a high on/off ratio of ˜105, a low ideality factor of 5.5, and a low reverse leakage current below 1 nA. Due to the ultra-wide bandgap of AlN, the device also exhibited excellent thermal stability over 500 K representing, therefore, a cost-effective route to high performance AlN based Schottky barrier diodes for high power, high voltage and high temperature applications.
    Type: Application
    Filed: November 1, 2018
    Publication date: May 9, 2019
    Inventors: Yuji Zhao, Houqiang Fu
  • Publication number: 20140167059
    Abstract: A method of performing a photoelectrochemical (PEC) etch on an exposed surface of a semipolar {20-2-1} III-nitride semiconductor, for improving light extraction from and for enhancing external efficiency of one or more active layers formed on or above the semipolar {20-2-1} III-nitride semiconductor.
    Type: Application
    Filed: August 30, 2013
    Publication date: June 19, 2014
    Inventors: Chung-Ta Hsu, Chia-Yen Huang, Yuji Zhao, Shih-Chieh Haung, Daniel F. Feezell, Steven P. DenBaars, Shuji Nakamura, James S. Speck
  • Publication number: 20140151634
    Abstract: A light emitting diode structure of (Al,Ga,In)N thin films grown on a gallium nitride (GaN) semipolar substrate by metal organic chemical vapor deposition (MOCVD) that exhibits reduced droop. The device structure includes a quantum well (QW) active region of two or more periods, n-type superlattice layers (n-SLs) located below the QW active region, and p-type superlattice layers (p-SLs) above the QW active region. The present invention also encompasses a method of fabricating such a device.
    Type: Application
    Filed: February 6, 2014
    Publication date: June 5, 2014
    Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Shuji Nakamura, Steven P. DenBaars, Shinichi Tanaka, Daniel F. Feezell, Yuji Zhao, Chih-Chien Pan