Patents by Inventor Evelyn L. Hu

Evelyn L. Hu 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: 20210210657
    Abstract: A gallium nitride (GaN) based light emitting diode (LED), wherein light is extracted through a nitrogen face (N-face) of the LED and a surface of the N-face is roughened into one or more hexagonal shaped cones. The roughened surface reduces light reflections occurring repeatedly inside the LED, and thus extracts more light out of the LED. The surface of the N-face is roughened by an anisotropic etching, which may comprise a dry etching or a photo-enhanced chemical (PEC) etching.
    Type: Application
    Filed: March 18, 2021
    Publication date: July 8, 2021
    Applicants: The Regents of the University of California
    Inventors: Tetsuo Fujii, Yan Gao, Evelyn L. Hu, Shuji Nakamura
  • Patent number: 10985293
    Abstract: A gallium nitride (GaN) based light emitting diode (LED), wherein light is extracted through a nitrogen face (N-face) of the LED and a surface of the N-face is roughened into one or more hexagonal shaped cones. The roughened surface reduces light reflections occurring repeatedly inside the LED, and thus extracts more light out of the LED. The surface of the N-face is roughened by an anisotropic etching, which may comprise a dry etching or a photo-enhanced chemical (PEC) etching.
    Type: Grant
    Filed: September 5, 2019
    Date of Patent: April 20, 2021
    Assignees: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA, JAPAN SCIENCE AND TECHNOLOGY AGENCY
    Inventors: Tetsuo Fujii, Yan Gao, Evelyn L. Hu, Shuji Nakamura
  • Publication number: 20200212258
    Abstract: A gallium nitride (GaN) based light emitting diode (LED), wherein light is extracted through a nitrogen face (N-face) of the LED and a surface of the N-face is roughened into one or more hexagonal shaped cones. The roughened surface reduces light reflections occurring repeatedly inside the LED, and thus extracts more light out of the LED. The surface of the N-face is roughened by an anisotropic etching, which may comprise a dry etching or a photo-enhanced chemical (PEC) etching.
    Type: Application
    Filed: September 5, 2019
    Publication date: July 2, 2020
    Inventors: Tetsuo Fujii, Yan Gao, Evelyn L. Hu, Shuji Nakamura
  • Patent number: 10446714
    Abstract: A gallium nitride (GaN) based light emitting diode (LED), wherein light is extracted through a nitrogen face (N-face) of the LED and a surface of the N-face is roughened into one or more hexagonal shaped cones. The roughened surface reduces light reflections occurring repeatedly inside the LED, and thus extracts more light out of the LED. The surface of the N-face is roughened by an anisotropic etching, which may comprise a dry etching or a photo-enhanced chemical (PEC) etching.
    Type: Grant
    Filed: May 19, 2014
    Date of Patent: October 15, 2019
    Assignees: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA, JAPAN SCIENCE AND TECHNOLOGY AGENCY
    Inventors: Tetsuo Fujii, Yan Gao, Evelyn L. Hu, Shuji Nakamura
  • Patent number: 10211428
    Abstract: A light emitting device is described that may reduce the coupling of emitted light into silicon and may increase the efficiency with which light is emitted into the far field. Such a device may include a semiconductor layer, a metallic structure, and a light emission layer disposed between the semiconductor layer and the metallic structure. The light emission layer may be in physical contact with the metallic structure and the semiconductor layer. The light emission layer may include at least one fluorescent molecule that emits light upon excitation.
    Type: Grant
    Filed: June 24, 2015
    Date of Patent: February 19, 2019
    Assignee: President and Fellows of Harvard College
    Inventors: Kasey Joe Russell, Tsung-Li Liu, Evelyn L. Hu
  • Publication number: 20170104180
    Abstract: A light emitting device including a semiconductor layer, a metallic structure, and a light emission layer disposed between the semiconductor layer and the metallic structure. The light emission layer is in physical contact with the metallic structure and the semiconductor layer. The light emission layer includes at least one fluorescent molecule that emits light of at least a first frequency upon excitation by an excitation signal.
    Type: Application
    Filed: June 24, 2015
    Publication date: April 13, 2017
    Applicant: President and Fellows of Harvard College
    Inventors: Kasey Joe Russell, Tsung-Li Liu, Evelyn L. Hu
  • Publication number: 20140252396
    Abstract: A gallium nitride (GaN) based light emitting diode (LED), wherein light is extracted through a nitrogen face (N-face) of the LED and a surface of the N-face is roughened into one or more hexagonal shaped cones. The roughened surface reduces light reflections occurring repeatedly inside the LED, and thus extracts more light out of the LED. The surface of the N-face is roughened by an anisotropic etching, which may comprise a dry etching or a photo-enhanced chemical (PEC) etching.
    Type: Application
    Filed: May 19, 2014
    Publication date: September 11, 2014
    Applicants: JAPAN SCIENCE AND TECHNOLOGY AGENCY, THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Tetsuo Fujii, Yan Gao, Evelyn L. Hu, Shuji Nakamura
  • Patent number: 8766296
    Abstract: A gallium nitride (GaN) based light emitting diode (LED), wherein light is extracted through a nitrogen face (N-face) of the LED and a surface of the N-face is roughened into one or more hexagonal shaped cones. The roughened surface reduces light reflections occurring repeatedly inside the LED, and thus extracts more light out of the LED. The surface of the N-face is roughened by an anisotropic etching, which may comprise a dry etching or a photo-enhanced chemical (PEC) etching.
    Type: Grant
    Filed: October 8, 2009
    Date of Patent: July 1, 2014
    Assignees: The Regents of the University of California, Japan Science and Technology Agency
    Inventors: Tetsuo Fujii, Yan Gao, Evelyn L. Hu, Shuji Nakamura
  • Patent number: 8569085
    Abstract: A photoelectrochemical (PEC) etch is performed for chip shaping of a device comprised of a III-V semiconductor material, in order to extract light emitted into guided modes trapped in the III-V semiconductor material. The chip shaping involves varying an angle of incident light during the PEC etch to control an angle of the resulting sidewalls of the III-V semiconductor material. The sidewalls may be sloped as well as vertical, in order to scatter the guided modes out of the III-V semiconductor material rather than reflecting the guided modes back into the III-V semiconductor material. In addition to shaping the chip in order to extract light emitted into guided modes, the chip may be shaped to act as a lens, to focus its output light, or to direct its output light in a particular way.
    Type: Grant
    Filed: October 9, 2009
    Date of Patent: October 29, 2013
    Assignee: The Regents of the University of California
    Inventors: Adele Tamboli, Evelyn L. Hu, James S. Speck
  • Patent number: 8263500
    Abstract: A method for fabricating a semiconductor laser device, by etching facets using a photoelectrochemical (PEC) etch, so that the facets are sufficiently smooth to support optical modes within a cavity bounded by the facets.
    Type: Grant
    Filed: February 1, 2010
    Date of Patent: September 11, 2012
    Assignee: The Regents of the University of California
    Inventors: Adele C. Tamboli, Evelyn L. Hu, Steven P. DenBaars, Arpan Chakraborty
  • Publication number: 20120018758
    Abstract: An optoelectronic structure, and method of fabricating same, comprised of semiconductors having growth-embedded void-gap gratings or photonic crystals in one or two dimensions, which are optimized to yield high interaction of the guided light and the photonic crystals and planar epitaxial growth. Such structure can be applied to increase light extraction efficiency in LEDs, increase modal confinement in lasers or increase light absorption in solar cells. The optimal dimensions of the growth-embedded void-gap gratings or photonic crystals are calculated by numerical simulation using scattering matrix formalism. The growth-embedded void-gap gratings are applicable to any semiconductor device, as well as optoelectronic devices, such as light-emitting diodes, laser diodes and solar cells.
    Type: Application
    Filed: July 25, 2011
    Publication date: January 26, 2012
    Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Elison de Nazareth Matioli, Claude C. A. Weisbuch, James S. Speck, Evelyn L. Hu
  • Publication number: 20100195684
    Abstract: A method for fabricating a semiconductor laser device, by etching facets using a photoelectrochemical (PEC) etch, so that the facets are sufficiently smooth to support optical modes within a cavity bounded by the facets.
    Type: Application
    Filed: February 1, 2010
    Publication date: August 5, 2010
    Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Adele C. Tamboli, Evelyn L. Hu, Steven P. DenBaars, Arpan Chakraborty
  • Patent number: 7704763
    Abstract: A gallium nitride (GaN) based light emitting diode (LED), wherein light is extracted through a nitrogen face (N-face) (42) of the LED and a surface of the N-face (42) is roughened into one or more hexagonal shaped cones. The roughened surface reduces light reflections occurring repeatedly inside the LED, and thus extracts more light out of the LED. The surface of the N-face (42) is roughened by an anisotropic etching, which may comprise a dry etching or a photo-enhanced chemical (PEC) etching.
    Type: Grant
    Filed: December 9, 2003
    Date of Patent: April 27, 2010
    Assignees: The Regents of the University of California, Japan Science and Technology Agency
    Inventors: Tetsuo Fujii, Yan Gao, Evelyn L. Hu, Shuji Nakamura
  • Publication number: 20100090240
    Abstract: A photoelectrochemical (PEC) etch is performed for chip shaping of a device comprised of a III-V semiconductor material, in order to extract light emitted into guided modes trapped in the III-V semiconductor material. The chip shaping involves varying an angle of incident light during the PEC etch to control an angle of the resulting sidewalls of the III-V semiconductor material. The sidewalls may be sloped as well as vertical, in order to scatter the guided modes out of the III-V semiconductor material rather than reflecting the guided modes back into the III-V semiconductor material. In addition to shaping the chip in order to extract light emitted into guided modes, the chip may be shaped to act as a lens, to focus its output light, or to direct its output light in a particular way.
    Type: Application
    Filed: October 9, 2009
    Publication date: April 15, 2010
    Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Adele Tamboli, Evelyn L. Hu, James S. Speck
  • Publication number: 20100025717
    Abstract: A gallium nitride (GaN) based light emitting diode (LED), wherein light is extracted through a nitrogen face (N-face) of the LED and a surface of the N-face is roughened into one or more hexagonal shaped cones. The roughened surface reduces light reflections occurring repeatedly inside the LED, and thus extracts more light out of the LED. The surface of the N-face is roughened by an anisotropic etching, which may comprise a dry etching or a photo-enhanced chemical (PEC) etching.
    Type: Application
    Filed: October 8, 2009
    Publication date: February 4, 2010
    Applicants: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Tetsuo Fujii, Yan Gao, Evelyn L. Hu, Shuji Nakamura
  • Patent number: 7550395
    Abstract: A method for locally controlling an electrical potential of a semiconductor structure or device, and hence locally controlling lateral and/or vertical photoelectrochemical (PEC) etch rates, by appropriate placement of electrically resistive layers or layers that impede electron flow within the semiconductor structure, and/or by positioning a cathode in contact with specific layers of the semiconductor structure during PEC etching.
    Type: Grant
    Filed: October 31, 2005
    Date of Patent: June 23, 2009
    Assignee: The Regents of the University of California
    Inventors: Evelyn L. Hu, Shuji Nakamura, Elaine D. Haberer, Rajat Sharma
  • Publication number: 20080182420
    Abstract: A method for ensuring the structural integrity of III-nitride opto-electronic or opto-mechanical air-gap nano-structured devices, comprising (a) performing ion beam implantation in a region of the III-nitride opto-electronic and opto-mechanical air-gap nano-structured device, wherein the milling significantly locally modifies a material property in the region to provide the structural integrity; and (b) performing a band-gap selective photo-electro-chemical (PEC) etch on the III-nitride opto-electronic and opto-mechanical air-gap nano-structured device. The method can be used to fabricate distributed Bragg reflectors or photonic crystals, for example.
    Type: Application
    Filed: November 15, 2007
    Publication date: July 31, 2008
    Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Evelyn L. Hu, Shuji Nakamura, Yong Seok Choi, Rajat Sharma, Chiou-Fu Wang
  • Patent number: 6884740
    Abstract: Photoelectrochemical (PEC) etching is restricted to a group III nitride semiconductor-barrier interface to laterally etch or undercut the target group III nitride. The barrier interface is provided by the transparent sapphire substrate on which the target group III nitride is epitaxially grown or by a layer of material in intimate contact with the target group III nitride material and having a bandgap sufficiently high to make it resistant to PEC etching. Due to the first orientation in which this effect was first observed, it has been named backside-Illuminated photoelectrochemical (BIPEC) etching. It refers to a preferential etching at the semiconductor-barrier layer interface. The assembly can be exposed to light from any direction to effectuate bandgap-selective PEC etching. An opaque mask can be applied to limit the lateral extent of the photoelectrochemical etching.
    Type: Grant
    Filed: September 3, 2002
    Date of Patent: April 26, 2005
    Assignee: The Regents of the University of California
    Inventors: Evelyn L. Hu, Andreas R. Stonas
  • Publication number: 20030045120
    Abstract: Photoelectrochemical (PEC) etching is restricted to a group III nitride semiconductor-barrier interface to laterally etch or undercut the target group III nitride. The barrier interface is provided by the transparent sapphire substrate on which the target group III nitride is epitaxially grown or by a layer of material in intimate contact with the target group III nitride material and having a bandgap sufficiently high to make it resistant to PEC etching. Due to the first orientation in which this effect was first observed, it has been named backside-Illuminated photoelectrochemical (BIPEC) etching. It refers to a preferential etching at the semiconductor-barrier layer interface. The assembly can be exposed to light from any direction to effectuate bandgap-selective PEC etching. An opaque mask can be applied to limit the lateral extent of the photoelectrochemical etching.
    Type: Application
    Filed: September 3, 2002
    Publication date: March 6, 2003
    Inventors: Evelyn L. Hu, Andreas R. Stonas
  • Patent number: 4370359
    Abstract: A self-aligning technique is used to produce small area junctions such as small area Josephson junctions. A base layer having a thickness corresponding to one dimension of the junction is first deposited. An insulating material is then deposited from a source positioned so that the base layer itself masks its edge from the insulator being formed. This procedure coats the base layer with an insulator, but leaves an edge of this layer free of insulation. A junction is then completed on this uncoated edge.
    Type: Grant
    Filed: August 18, 1980
    Date of Patent: January 25, 1983
    Assignee: Bell Telephone Laboratories, Incorporated
    Inventors: Linus A. Fetter, Richard E. Howard, Evelyn L. Hu, Lawrence D. Jackel