Patents by Inventor Andrew D. Koehler

Andrew D. Koehler 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: 9490356
    Abstract: Methods for forming a high-quality III-nitride passivation layer on an AlGaN/GaN HEMT. A III-nitride passivation layer is formed on the surface of an AlGaN/GaN HEMT by means of atomic layer epitaxy (ALE), either before or after deposition of a gate metal electrode on the AlGaN barrier layer. Depending on the gate metal and/or the passivation material used, the III-nitride passivation layer can be formed by ALE at temperatures between about 300° C. and about 85020 C. In a specific embodiment, the III-nitride passivation layer can be an AlN layer formed by ALE at about 550° C. after deposition of a Schottky metal gate electrode. The III-nitride passivation layer can be grown so as to conformally cover the entire device, providing a hermetic seal that protects the against environmental conditions.
    Type: Grant
    Filed: March 25, 2016
    Date of Patent: November 8, 2016
    Assignee: The United States of America, as represented by the Secretary of the Navy
    Inventors: Andrew D. Koehler, Travis J. Anderson, Karl D. Hobart, Francis J. Kub
  • Patent number: 9466684
    Abstract: A field effect transistor having a diamond gate electrode and a process for forming the same. In some embodiments, the device is an AlGaN/GaN high-electron-mobility transistor (HEMT). The diamond gate electrode is formed so that it directly contacts the barrier layer. In some embodiments, the diamond gate electrode is formed from boron-doped nanocrystalline diamond (NCD), while in other embodiments, the diamond gate electrode is formed from single crystal diamond.
    Type: Grant
    Filed: March 25, 2016
    Date of Patent: October 11, 2016
    Assignee: The United States of America, as represented by the Secretary of the Navy
    Inventors: Andrew D. Koehler, Travis J. Anderson, Marko J. Tadjer, Karl D. Hobart, Tatyana I. Feygelson
  • Publication number: 20160211341
    Abstract: A field effect transistor having a diamond gate electrode and a process for forming the same. In some embodiments, the device is an AlGaN/GaN high-electron-mobility transistor (HEMT). The diamond gate electrode is formed so that it directly contacts the barrier layer. In some embodiments, the diamond gate electrode is formed from boron-doped nanocrystalline diamond (NCD), while in other embodiments, the diamond gate electrode is formed from single crystal diamond.
    Type: Application
    Filed: March 25, 2016
    Publication date: July 21, 2016
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Andrew D. Koehler, Travis J. Anderson, Marko J. Tadjer, Karl D. Hobart, Tatyana I. Feygelson
  • Publication number: 20160204222
    Abstract: Methods for forming a high-quality III-nitride passivation layer on an AlGaN/GaN HEMT. A III-nitride passivation layer is formed on the surface of an AlGaN/GaN HEMT by means of atomic layer epitaxy (ALE), either before or after deposition of a gate metal electrode on the AlGaN barrier layer. Depending on the gate metal and/or the passivation material used, the III-nitride passivation layer can be formed by ALE at temperatures between about 300° C. and about 85020 C. In a specific embodiment, the III-nitride passivation layer can be an AlN layer formed by ALE at about 550° C. after deposition of a Schottky metal gate electrode. The III-nitride passivation layer can be grown so as to conformally cover the entire device, providing a hermetic seal that protects the against environmental conditions.
    Type: Application
    Filed: March 25, 2016
    Publication date: July 14, 2016
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Andrew D. Koehler, Travis J. Anderson, Karl D. Hobart, Francis J. Kub
  • Patent number: 9331163
    Abstract: A field effect transistor having a diamond gate electrode and a process for forming the same. In some embodiments, the device is an AlGaN/GaN high-electron-mobility transistor (HEMT). The diamond gate electrode is formed so that it directly contacts the barrier layer. In some embodiments, the diamond gate electrode is formed from boron-doped nanocrystalline diamond (NCD), while in other embodiments, the diamond gate electrode is formed from single crystal diamond.
    Type: Grant
    Filed: August 28, 2014
    Date of Patent: May 3, 2016
    Assignee: The United States of America, as represented by the Secretary of the Navy
    Inventors: Andrew D. Koehler, Travis J. Anderson, Marko J. Tadjer, Tatyana I. Feygelson, Karl D. Hobart
  • Publication number: 20160087087
    Abstract: A method of making a graphene base transistor with reduced collector area comprising forming a graphene material layer, forming a collector material, depositing a dielectric, planarizing the dielectric, cleaning and removing the native oxide, transferring a base graphene material layer to the top surface of the graphene material layer, bonding the base graphene material layer, and photostepping and defining a second graphene material layer. A method of making a graphene base transistor with reduced collector area comprising forming an electron injection region, forming an electron collection region, and forming a base region. A graphene base transistor with reduced collector area comprising an electron emitter region, an electron collection region, and a base region.
    Type: Application
    Filed: November 25, 2015
    Publication date: March 24, 2016
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Andrew D. Koehler
  • Patent number: 9275998
    Abstract: An inverted P-channel III-nitride field effect transistor with hole carriers in the channel comprising a gallium-polar III-Nitride grown epitaxially on a substrate, a barrier, a two-dimensional hole gas in the barrier layer material at the heterointerface of the first material, and wherein the gallium-polar III-Nitride material comprises III-Nitride epitaxial material layers grown in such a manner that when GaN is epitaxially grown the top surface of the epitaxial layer is gallium-polar. A method of making a P-channel III-nitride field effect transistor with hole carriers in the channel comprising selecting a face of a substrate so that the gallium-polar (0001) face is the dominant face for growth of III-Nitride epitaxial layer growth material, growing a GaN epitaxial layer, doping, growing a barrier, etching, forming a contact, performing device isolation, defining a gate opening, defining gate metal, making a contact window, and depositing and defining a thick metal.
    Type: Grant
    Filed: April 29, 2014
    Date of Patent: March 1, 2016
    Assignee: The United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Andrew D. Koehler, Karl D. Hobart
  • Patent number: 9236432
    Abstract: A graphene base transistor with reduced collector area comprising an electron injection region, an electron collection region, and a base region wherein the base region comprises one or more sheets of graphene and wherein the base region is intermediate the electron injection region and the electron collection region and forms electrical interfaces therewith. A method of making a graphene base transistor with reduced collector area comprising forming an electron injection region, forming an electron collection region, and forming a base region wherein the base region comprises one or more sheets of graphene and wherein the base region is intermediate the electron injection region and the electron collection region and forms electrical interfaces therewith.
    Type: Grant
    Filed: February 12, 2014
    Date of Patent: January 12, 2016
    Assignee: The United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Andrew D. Koehler
  • Patent number: 9196703
    Abstract: A method for fabricating a semiconductor device, such as a GaN high electron mobility transistor (HEMT) device, including etching a thermal via into a back-side of a semiconductor substrate and depositing a diamond nucleation seed layer across the back-side of the substrate. The method further includes coating the diamond nucleation with a mask layer and removing mask material outside of the thermal via on the planar portions of the back-side of the substrate. The method includes removing portions of the diamond nucleation layer on the planar portions and then removing the remaining portion of the mask material in the thermal via. The method then includes depositing a bulk diamond layer within the thermal via on the remaining portion of the diamond nucleation layer so that diamond only grows in the thermal via and not on the planar portions of the substrate.
    Type: Grant
    Filed: August 20, 2014
    Date of Patent: November 24, 2015
    Assignees: Northrop Grumman Systems Corporation, The United States of America, as Represented by the Secretary of the Navy, The Regents of the University of California
    Inventors: Karl D. Hobart, Tatyana I. Feygelson, Eugene I. Imhoff, Travis J. Anderson, Joshua D. Caldwell, Andrew D. Koehler, Bradford B. Pate, Marko J. Tadjer, Rajinder S. Sandhu, Vincent Gambin, Gregory Lewis, Ioulia Smorchkova, Mark Goorsky, Jeff McKay
  • Patent number: 9196614
    Abstract: An inverted P-channel III-nitride field effect transistor with hole carriers in the channel comprising a gallium-polar III-Nitride barrier material, a second material layer, a two-dimensional hole gas in the second layer, and wherein the gallium-polar material comprises one or more III-Nitride epitaxial material layers grown such that when GaN is epitaxially grown the top surface of the epitaxial layer is gallium-polar. A method of making an inverted P-channel III-nitride field effect transistor with hole carriers in the channel comprising selecting a face or offcut orientation of a substrate so that the gallium-polar (0001) face is the dominant face, growing a nucleation layer, growing a gallium-polar epitaxial layer, doping the epitaxial layer, growing a barrier layer, etching the GaN, forming contacts, performing device isolation, defining a gate opening, depositing and defining gate metal, making a contact window, depositing and defining a thick metal.
    Type: Grant
    Filed: February 9, 2015
    Date of Patent: November 24, 2015
    Assignee: The United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Andrew D. Koehler, Karl D. Hobart
  • Publication number: 20150221760
    Abstract: An inverted P-channel III-nitride field effect transistor with hole carriers in the channel comprising a gallium-polar III-Nitride first material, a barrier material layer, a two-dimensional hole gas in the barrier layer, and wherein the gallium-polar material comprises one or more III-Nitride epitaxial material layers grown such that when GaN is epitaxially grown the top surface of the epitaxial layer is gallium-polar. A method of making an inverted P-channel III-nitride field effect transistor with hole carriers in the channel comprising selecting a face or offcut orientation of a substrate so that the gallium-polar (0001) face is the dominant face, growing a nucleation layer, growing a gallium-polar epitaxial layer, doping the epitaxial layer, growing a barrier layer, etching the GaN, forming contacts, performing device isolation, defining a gate opening, depositing and defining gate metal, making a contact window, depositing and defining a thick metal.
    Type: Application
    Filed: February 9, 2015
    Publication date: August 6, 2015
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Andrew D. Koehler, Karl D. Hobart
  • Publication number: 20150221727
    Abstract: An inverted P-channel III-nitride field effect transistor with hole carriers in the channel comprising a gallium-polar III-Nitride grown epitaxially on a substrate, a barrier, a two-dimensional hole gas in the barrier layer material at the heterointerface of the first material, and wherein the gallium-polar III-Nitride material comprises III-Nitride epitaxial material layers grown in such a manner that when GaN is epitaxially grown the top surface of the epitaxial layer is gallium-polar. A method of making a P-channel III-nitride field effect transistor with hole carriers in the channel comprising selecting a face of a substrate so that the gallium-polar (0001) face is the dominant face for growth of III-Nitride epitaxial layer growth material, growing a GaN epitaxial layer, doping, growing a barrier, etching, forming a contact, performing device isolation, defining a gate opening, defining gate metal, making a contact window, and depositing and defining a thick metal.
    Type: Application
    Filed: April 29, 2014
    Publication date: August 6, 2015
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Andrew D. Koehler, Karl D. Hobart
  • Patent number: 9006791
    Abstract: A non-inverted P-channel III-nitride field effect transistor with hole carriers in the channel comprising a nitrogen-polar III-Nitride first material, a barrier material layer, a two-dimensional hole gas in the barrier layer, and wherein the nitrogen-polar III-Nitride material comprises one or more III-Nitride epitaxial material layers grown in such a manner that when GaN is epitaxially grown the top surface of the epitaxial layer is nitrogen-polar. A method of making a P-channel III-nitride field effect transistor with hole carriers in the channel comprising selecting a face or offcut orientation of a substrate so that the nitrogen-polar (001) face is the dominant face, growing a nucleation layer, growing a GaN epitaxial layer, doping the epitaxial layer, growing a barrier layer, etching the GaN, forming contacts, performing device isolation, defining a gate opening, depositing and defining gate metal, making a contact window, depositing and defining a thick metal.
    Type: Grant
    Filed: January 31, 2014
    Date of Patent: April 14, 2015
    Assignee: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Andrew D. Koehler, Karl D. Hobart
  • Publication number: 20150060947
    Abstract: A field effect transistor having a diamond gate electrode and a process for forming the same. In some embodiments, the device is an AlGaN/GaN high-electron-mobility transistor (HEMT). The diamond gate electrode is formed so that it directly contacts the barrier layer. In some embodiments, the diamond gate electrode is formed from boron-doped nanocrystalline diamond (NCD), while in other embodiments, the diamond gate electrode is formed from single crystal diamond.
    Type: Application
    Filed: August 28, 2014
    Publication date: March 5, 2015
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Andrew D. Koehler, Travis J. Anderson, Marko J. Tadjer, Tatyana I. Feygelson, Karl D. Hobart
  • Publication number: 20150056763
    Abstract: A method for fabricating a semiconductor device, such as a GaN high electron mobility transistor (HEMT) device, including etching a thermal via into a back-side of a semiconductor substrate and depositing a diamond nucleation seed layer across the back-side of the substrate. The method further includes coating the diamond nucleation with a mask layer and removing mask material outside of the thermal via on the planar portions of the back-side of the substrate. The method includes removing portions of the diamond nucleation layer on the planar portions and then removing the remaining portion of the mask material in the thermal via. The method then includes depositing a bulk diamond layer within the thermal via on the remaining portion of the diamond nucleation layer so that diamond only grows in the thermal via and not on the planar portions of the substrate.
    Type: Application
    Filed: August 20, 2014
    Publication date: February 26, 2015
    Inventors: Karl D. Hobart, Tatyana I. Feygelson, Eugene A. Imhoff, Travis J. Anderson, Joshua D. Caldwell, Andrew D. Koehler, Bradford B. Pate, Marko J. Tadjer, Randijer S. Sandhu, Vincent Gambin, Gregory Lewis, Ioulia Smorchkova, Mark Goorsky, Jeff McKay
  • Publication number: 20140335666
    Abstract: Methods for forming a high-quality III-nitride passivation layer on an AlGaN/GaN HEMT. A III-nitride passivation layer is formed on the surface of an AlGaN/GaN HEMT by means of atomic layer epitaxy (ALE), either before or after deposition of a gate metal electrode on the AlGaN barrier layer. Depending on the gate metal and/or the passivation material used, the III-nitride passivation layer can be formed by ALE at temperatures between about 300° C. and about 850° C. In a specific embodiment, the III-nitride passivation layer can be an AlN layer formed by ALE at about 550° C. after deposition of a Schottky metal gate electrode. The III-nitride passivation layer can be grown so as to conformally cover the entire device, providing a hermetic seal that protects the against environmental conditions.
    Type: Application
    Filed: May 8, 2014
    Publication date: November 13, 2014
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Andrew D. Koehler, Travis J. Anderson, Karl D. Hobart, Francis J. Kub
  • Publication number: 20140284552
    Abstract: A graphene base transistor with reduced collector area comprising an electron injection region, an electron collection region, and a base region wherein the base region comprises one or more sheets of graphene and wherein the base region is intermediate the electron injection region and the electron collection region and forms electrical interfaces therewith. A method of making a graphene base transistor with reduced collector area comprising forming an electron injection region, forming an electron collection region, and forming a base region wherein the base region comprises one or more sheets of graphene and wherein the base region is intermediate the electron injection region and the electron collection region and forms electrical interfaces therewith.
    Type: Application
    Filed: February 12, 2014
    Publication date: September 25, 2014
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Andrew D. Koehler
  • Publication number: 20140264379
    Abstract: A non-inverted P-channel III-nitride field effect transistor with hole carriers in the channel comprising a nitrogen-polar III-Nitride first material, a barrier material layer, a two-dimensional hole gas in the barrier layer, and wherein the nitrogen-polar III-Nitride material comprises one or more III-Nitride epitaxial material layers grown in such a manner that when GaN is epitaxially grown the top surface of the epitaxial layer is nitrogen-polar. A method of making a P-channel III-nitride field effect transistor with hole carriers in the channel comprising selecting a face or offcut orientation of a substrate so that the nitrogen-polar (001) face is the dominant face, growing a nucleation layer, growing a GaN epitaxial layer, doping the epitaxial layer, growing a barrier layer, etching the GaN, forming contacts, performing device isolation, defining a gate opening, depositing and defining gate metal, making a contact window, depositing and defining a thick metal.
    Type: Application
    Filed: January 31, 2014
    Publication date: September 18, 2014
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Andrew D. Koehler, Karl D. Hobart