Patents by Inventor Srinivas Gandrothula

Srinivas Gandrothula 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: 20220108883
    Abstract: A method for flattening a surface on an epitaxial lateral overgrowth (ELO) layer, resulting in obtaining a smooth surface with island-like III-nitride semiconductor layers. The island-like III-nitride semiconductor layers are formed by stopping the growth of the ELO layers before they coalesce to each other. Then, a growth restrict mask is removed before at least some III-nitride device layers are grown. Removing the mask decreases an excess gases supply to side facets of the island-like III-nitride semiconductor layers, which can help to obtain a smooth surface on the island-like III-nitride semiconductor layers. The method also avoids compensation of a p-type layer by decomposed n-type dopant from the mask, such as Silicon and Oxygen atoms.
    Type: Application
    Filed: March 2, 2020
    Publication date: April 7, 2022
    Applicant: The Regents of the University of California
    Inventors: Takeshi Kamikawa, Srinivas Gandrothula
  • Publication number: 20210381124
    Abstract: A method for obtaining a smooth surface of an epi-layer with epitaxial lateral overgrowth. The method does not use mis-cut orientations and does not suppress the occurrence of pyramidal hillocks, but instead embeds the pyramidal hillocks in the epi-layer. A growth restrict mask is used to limit the expansion of the pyramidal hillocks in a lateral direction. The surface of the epi-layer becomes extremely smooth due to the disappearance of the pyramidal hillocks.
    Type: Application
    Filed: October 31, 2019
    Publication date: December 9, 2021
    Applicant: The Regents of the University of California
    Inventors: Takeshi Kamikawa, Srinivas Gandrothula
  • Publication number: 20210242086
    Abstract: A method of removing semiconducting layers from a substrate, in particular, III-nitride-based semiconductor layers from a III-nitride-based substrate, with an attached film, using a peeling technique. The method comprises forming the semiconductor layers into island-like patterns on the substrate via an epitaxial lateral overgrowth method, with a horizontal trench extending inwards from the sides of the layers. Stress is induced in the layers by raising or lowering the temperature, and applying pressure to the attached film, such that the film firmly fits a shape of the layers. Differences in thermal expansion between the substrate and the film attached to the layers initiates a crack at an interface between the layers and the substrate, so that the layers can be removed from the substrate. Once the layers are removed, the substrate can be recycled, resulting in cost savings for device fabrication.
    Type: Application
    Filed: May 30, 2019
    Publication date: August 5, 2021
    Applicant: The Regents of the University of California
    Inventors: Srinivas Gandrothula, Takeshi Kamikawa
  • Publication number: 20210090885
    Abstract: A method for dividing a bar of one or more devices. The bar is comprised of island-like III-nitride-based semiconductor layers grown on a substrate using a growth restrict mask; the island-like III-nitride-based semiconductor layers are removed from the substrate using an Epitaxial Lateral Overgrowth (ELO) method; and then the bar is divided into the one or more devices using a cleaving method.
    Type: Application
    Filed: May 17, 2019
    Publication date: March 25, 2021
    Applicant: The Regents of the University of California
    Inventors: Takeshi Kamikawa, Srinivas Gandrothula
  • Publication number: 20210013365
    Abstract: A method of fabricating a semiconductor device, comprising: forming a growth restrict mask on or above a III-nitride substrate, and growing one or more island-like III-nitride semiconductor layers on the III-nitride substrate using the growth restrict mask The III-nitride substrate has an in-plane distribution of off-angle orientations with more than 0.1 degree; and the off-angle orientations of an m-plane oriented crystalline surface plane range from about +28 degrees to about ?47 degrees towards a c-plane. The island-like III-nitride semiconductor layers have at least one long side and short side, wherein the long side is perpendicular to an a-axis of the island-like III-nitride semiconductor layers. The island-like III-nitride semiconductor layers do not coalesce with neighboring island-like III-nitride semiconductor layers.
    Type: Application
    Filed: April 1, 2019
    Publication date: January 14, 2021
    Applicant: The Regents of the University of California
    Inventors: Takeshi Kamikawa, Srinivas Gandrothula, Hongjian Li
  • Publication number: 20200203228
    Abstract: A method of removing a substrate from III-nitride based semiconductor layers with a cleaving technique. A growth (57) restrict mask is formed on or above a substrate, and one or more III-nitride based semiconductor layers are grown on or above the substrate using the growth restrict mask. The III-nitride based semiconductor layers are bonded to a support substrate or film, and the III-nitride based semiconductor layers are removed from the substrate using a cleaving technique on a surface of the substrate. Stress may be applied to the III-nitride based semiconductor layers, due to differences in thermal expansion between the III-nitride substrate and the support substrate or film bonded to the III-nitride based semiconductor layers, before the III-nitride based semiconductor layers are removed from the substrate. Once removed, the substrate can be recycled, resulting in cost savings for device fabrication.
    Type: Application
    Filed: September 17, 2018
    Publication date: June 25, 2020
    Applicant: The Regents of the University of California
    Inventors: Takeshi Kamikawa, Srinivas Gandrothula, Hongjian Li
  • Publication number: 20200194615
    Abstract: A method of removing a substrate, comprising: forming a growth restrict mask with a plurality of striped opening areas directly or indirectly upon a GaN-based substrate; and growing a plurality of semiconductor layers upon the GaN-based substrate using the growth restrict mask, such that the growth extends in a direction parallel to the striped opening areas of the growth restrict mask, and growth is stopped before the semiconductor layers coalesce, thereby resulting in island-like semiconductor layers. A device is processed for each of the island-like semiconductor layers. Etching is performed until at least a part of the growth restrict mask is exposed. The devices are then bonded to a support substrate. The GaN-based substrate is removed from the devices by a wet etching technique that at least partially dissolves the growth restrict mask. The GaN substrate that is removed then can be recycled.
    Type: Application
    Filed: May 7, 2018
    Publication date: June 18, 2020
    Applicant: THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
    Inventors: Takeshi Kamikawa, Srinivas Gandrothula, Hongjian Li, Daniel A. Cohen
  • Patent number: 10365048
    Abstract: A multiply-wound tube includes: a tube body formed by winding, into a roll, a metal plate comprising a core material layer made of a first metal material and a brazing material layer made of a second metal material having a lower melting point than the core material layer; and a joint portion that is formed at a portion of the metal plate that is wound in layers, wherein the portion of the metal plate that is wound in layers is brazed together by the brazing material layer being melted by heat from a laser projected onto the tube body.
    Type: Grant
    Filed: July 29, 2016
    Date of Patent: July 30, 2019
    Assignee: SANOH INDUSTRIAL CO., LTD.
    Inventors: Srinivas Gandrothula, Takuma Endo
  • Publication number: 20180231334
    Abstract: A multiply-wound tube includes: a tube body formed by winding, into a roll, a metal plate comprising a core material layer made of a first metal material and a brazing material layer made of a second metal material having a lower melting point than the core material layer; and a joint portion that is formed at a portion of the metal plate that is wound in layers, wherein the portion of the metal plate that is wound in layers is brazed together by the brazing material layer being melted by heat from a laser projected onto the tube body.
    Type: Application
    Filed: July 29, 2016
    Publication date: August 16, 2018
    Inventors: Srinivas Gandrothula, Takuma Endo