Patents by Inventor Karl D. Hobart

Karl D. Hobart 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: 20240234139
    Abstract: A method for growing nanocrystalline diamond (NCD) on Ga2O3 to provide thermal management in Ga2O3-based devices. A protective SiNx interlayer is deposited on the Ga2O3 before growth of the NCD layer to protect the Ga2O3 from damage caused during growth of the NCD layer. The presence of the NCD provides thermal management and enables improved performance of the Ga2O3-based device.
    Type: Application
    Filed: October 20, 2023
    Publication date: July 11, 2024
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Marko J. Tadjer, Joseph A. Spencer, Alan G. Jacobs, Hannah N. Masten, James Spencer Lundh, Karl D. Hobart, Travis J. Anderson, Tatyana I. Feygelson, Bradford B. Pate, Boris N. Feigelson
  • Patent number: 12020985
    Abstract: Methods for obtaining a free-standing thick (>5 ?m) epitaxial material layer or heterostructure stack and for transferring the thick epitaxial layer or stack to an arbitrary substrate. A thick epitaxial layer or heterostructure stack is formed on an engineered substrate, with a sacrificial layer disposed between the epitaxial layer and the engineered substrate. When the sacrificial layer is removed, the epitaxial layer becomes a thick freestanding layer that can be transferred to an arbitrary substrate, with the remaining engineered substrate being reusable for subsequent material layer growth. In an exemplary case, the material layer is a GaN layer and can be selectively bonded to an arbitrary substrate to selectively produce a Ga-polar or an N-polar GaN layer.
    Type: Grant
    Filed: May 24, 2021
    Date of Patent: June 25, 2024
    Assignee: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Travis J. Anderson, Marko J. Tadjer, Karl D. Hobart
  • Patent number: 11996840
    Abstract: Light controlled switching modules are provide. In embodiments, a light controlled switching module includes: a housing; a light controlled semiconductor switch mounted to the housing, the light controlled semiconductor switch including a semiconductor body; at least one light source mounted to the housing in a spaced relationship from the light controlled semiconductor switch and positioned to direct light emitted from the at least one light source toward the semiconductor body; and first and second electrodes mounted to the housing and connected to the light controlled semiconductor switch, wherein the first and second electrodes are configured to have variable resistance between the first and the second electrode.
    Type: Grant
    Filed: September 8, 2023
    Date of Patent: May 28, 2024
    Assignee: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Andrew D Koehler, Travis J. Anderson, Geoffrey M. Foster, Karl D. Hobart, Francis J. Kub, Michael A. Mastro
  • Publication number: 20240136180
    Abstract: A method for growing nanocrystalline diamond (NCD) on Ga2O3 to provide thermal management in Ga2O3-based devices. A protective SiNx interlayer is deposited on the Ga2O3 before growth of the NCD layer to protect the Ga2O3 from damage caused during growth of the NCD layer. The presence of the NCD provides thermal management and enables improved performance of the Ga2O3-based device.
    Type: Application
    Filed: October 19, 2023
    Publication date: April 25, 2024
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Marko J. Tadjer, Joseph A. Spencer, Alan G. Jacobs, Hannah N. Masten, James Spencer Lundh, Karl D. Hobart, Travis J. Anderson, Tatyana I. Feygelson, Bradford B. Pate, Boris N. Feigelson
  • Publication number: 20240120201
    Abstract: A technique for selective-area diffusion doping of III-N epitaxial material layers and for fabricating power device structures utilizing this technique. Dopant species such as Mg are introduced into the III-N material layer and are diffused into the III-N material by annealing under stable or metastable conditions. The dopant species can be introduced via deposition of a metal or alloy layer containing such species using sputtering, e-beam evaporation or other technique known to those skilled in the art. The dopant material layer is capped with a thermally stable layer to prevent decomposition and out-diffusion, and then is annealed under stable or metastable conditions to diffuse the dopant into the III-N material GaN without decomposing the surface.
    Type: Application
    Filed: March 31, 2023
    Publication date: April 11, 2024
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Travis J. Anderson, Mona A. Ebrish, Alan G. Jacobs, Karl D. Hobart, Francis J. Kub
  • Publication number: 20240097064
    Abstract: A light controlled semiconductor switch (LCSS), method of making, and method of using are provided. In embodiments, a vertical LCSS includes: a semiconductor body including a photoactive layer of gallium nitride (GaN) doped with carbon; a first electrode in contact with a first surface of the semiconductor body, the first electrode defining an area through which light energy from at least one light source can impinge on the first surface; and a second electrode in contact with a second surface of the semiconductor body opposed to the first surface, wherein the vertical LCSS is configured to switch from a non-conductive off-state to a conductive on-state when the light energy impinging on the semiconductor body is sufficient to raise electrons within the photoactive layer into a conduction band of the photoactive layer.
    Type: Application
    Filed: September 8, 2023
    Publication date: March 21, 2024
    Inventors: Andrew D. Koehler, Travis J. Anderson, Geoffrey M. Foster, Karl D. Hobart, Francis J. Kub, Michael A. Mastro
  • Publication number: 20230420539
    Abstract: A self-aligned lithography process for the fabrication of an electronic device having predefined areas of a second semiconductor material having a second conductivity type deposited into trenches formed in a first semiconductor material layer having a first conductivity type. A single lithography mask is used for etching trenches in the first semiconductor material, enabling cleaning of the trenches, and providing defined areas for the deposition of the second semiconductor material into the first semiconductor material. The presence of the areas of the second semiconductor material within the first semiconductor material creates a heterojunction beneath a metal for the formation of a first type of contact to the first semiconductor material and a second type of contact to the second type of material. By using a single mask for the etching, cleaning, and filling steps, misalignment issues plaguing devices having small (1-2 ?m) feature sizes is eliminated.
    Type: Application
    Filed: June 23, 2023
    Publication date: December 28, 2023
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Joseph A. Spencer, Marko J. Tadjer, Alan G. Jacobs, Karl D. Hobart, Yuhao Zhang
  • Publication number: 20230352541
    Abstract: Semiconductor heterostructures having an engineered polarization. Semiconductor materials having specified crystallographic directions and specified polarizations are directly bonded to one another by means of atomic layer bonding without the use of any interfacial bonding materials, where spontaneous polarization of the two layers produced by joining the two materials by direct wafer bonding produces a strong 2DEG or 2DHG at the interface. Embodiments include GaN/AlN and AlN/GaN heterostructures having an N- or Ga-polar GaN layer directly bonded to an N- or Al-polar Al layer. Other embodiments can incorporate an InN epitaxial layer or an alloy incorporating an N-polar, Al-polar, or Ga-polar material having In, Al, or Ga in the crystal lattice, e.g., (InxAl1-xN), InxGa1-xN, AlxGa1-xN, InxAlyGa1-x-yN, where (0<x?1, 0<y?1, 0<x+y?1).
    Type: Application
    Filed: April 28, 2022
    Publication date: November 2, 2023
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Karl D. Hobart, Marko J. Tadjer, Michael A. Mastro, Mark Goorsky, Asif Khan, Samuel Graham, Jr.
  • Publication number: 20230352600
    Abstract: Ga2O3-based rectifier structure and method of forming the same. A Schottky diode structure is combined with a metal-oxide-semiconductor structure to provide a metal oxide-type Schottky barrier diode (MOSSBD) rectifier that includes an n-type ?-Ga2O3 drift layer on a ?-Ga2O3 substrate, the drift layer having a plurality of spaced-apart semi-insulating regions formed by in-situ ion implantation of acceptor species at predefined spatially defined regions of the drift layer to create alternating areas of n-type and semi-insulating regions within the n-type drift layer. The thus-formed structure achieves high forward bias current with low specific on-resistance when the anode is biased with positive voltage and low leakage current when the device is operated under reverse bias.
    Type: Application
    Filed: April 28, 2023
    Publication date: November 2, 2023
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Marko J. Tadjer, Hannah N. Masten, Joseph A. Spencer, Alan G. Jacobs, Karl D. Hobart, Yuhao Zhang
  • Publication number: 20230352571
    Abstract: Semiconductor heterostructures having an engineered polarization. Semiconductor materials having specified crystallographic directions and specified polarizations are directly bonded to one another by means of atomic layer bonding without the use of any interfacial bonding materials, where spontaneous polarization of the two layers produced by joining the two materials by direct wafer bonding produces a strong 2DEG or 2DHG at the interface. Embodiments include GaN/AIN and AlN/GaN heterostructures having an N- or Ga-polar GaN layer directly bonded to an N- or Al-polar Al layer. Other embodiments can incorporate an InN epitaxial layer or an alloy incorporating an N-polar, Al-polar, or Ga-polar material having In, Al, or Ga in the crystal lattice, e.g., (InxAl1-xN), InxGa1-xN, AlxGa1-xN, InxAlyGa1-x-yN, where (0<x?1, 0<y?1, 0<x+y?1).
    Type: Application
    Filed: April 28, 2022
    Publication date: November 2, 2023
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Karl D. Hobart, Marko J. Tadjer, Michael A. Mastro, Mark Goorsky, Asif Khan, Samuel Graham, JR.
  • Patent number: 11649159
    Abstract: A method of fabricating suspended beam silicon carbide microelectromechanical (MEMS) structure with low capacitance and good thermal expansion match. A suspended material structure is attached to an anchor material structure that is direct wafer bonded to a substrate. The anchor material structure and the suspended material structure are formed from either a hexagonal single-crystal SiC material, and the anchor material structure is bonded to the substrate while the suspended material structure does not have to be attached to the substrate. The substrate may be a semi-insulating or insulating SiC substrate. The substrate may have an etched recess region on the substrate first surface to facilitate the formation of the movable suspended material structures. The substrate may have patterned electrical electrodes on the substrate first surface, within recesses etched into the substrate.
    Type: Grant
    Filed: September 14, 2020
    Date of Patent: May 16, 2023
    Inventors: Francis J. Kub, Karl D. Hobart, Eugene A. Imhoff, Rachael L. Myers-Ward
  • Patent number: 11634834
    Abstract: A method for growing polycrystalline diamond films having engineered grain growth and microstructure. Grain growth of a polycrystalline diamond film on a substrate is manipulated by growing the diamond on a nanopatterned substrate having features on the order of the initial grain size of the diamond film. By growing the diamond on such nanopatterned substrates, the crystal texture of a polycrystalline diamond film can be engineered to favor the preferred <110> orientation texture, which in turn enhances the thermal conductivity of the diamond film.
    Type: Grant
    Filed: August 24, 2021
    Date of Patent: April 25, 2023
    Assignee: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Karl D. Hobart, Tatyana I. Feygelson, Marko J. Tadjer, Travis J. Anderson, Andrew D. Koehler, Samuel Graham, Jr., Mark Goorsky, Zhe Cheng, Luke Yates, Tingyu Bai, Yekan Wang
  • Publication number: 20230030549
    Abstract: A hybrid edge termination structure and method of forming the same. The hybrid edge termination structure in accordance with the invention is based on a junction termination extension (JTE) architecture, but includes an additional Layer of guard ring (GR) structures to further implement the implantation of dopants into the structure. The hybrid edge termination structure of the invention has a three-Layer structure, with a top Layer and a bottom Layer each having a constant dopant concentration in the lateral direction, and a middle Layer consisting of a plurality of spatially defined alternating regions that exhibit the electrical properties of either the top or bottom layer. By including the second layer, a discretized varying charge profile can be obtained that approximates the varying charge profile obtained using tapered edge termination but with easier manufacturing and lower cost.
    Type: Application
    Filed: July 28, 2022
    Publication date: February 2, 2023
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Travis J. Anderson, Mona A. Ebrish, Andrew D. Koehler, Alan G. Jacobs, Matthew A. Porter, Karl D. Hobart, Prakash Pandey, Tolen Michael Nelson, Daniel G. Georgiev, Raghav Khanna, Michael Robert Hontz
  • Patent number: 11415518
    Abstract: A method for mapping and analyzing a GaN substrate to identify areas of the substrate suitable for fabrication of electronic devices thereon. Raman spectroscopy is performed over the surface of a GaN substrate to produce maps of the E2 and A1 peaks at a plurality of areas on the substrate surface, the E2 and A1 peaks being associated with known concentrations of defects and charge carriers, so that areas of the GaN substrate having relatively high resistivity or conductivity which make those areas suitable or unsuitable for fabrication of electronic devices can be identified. The devices can then be fabricated only on suitable areas of the substrate, or the size of the devices can be tailored to maximize the yield of devices fabricated thereon. Substrates not meeting a threshold level of defect and/or charge carrier concentration can be discarded without fabrication of poor-quality devices thereon.
    Type: Grant
    Filed: June 19, 2020
    Date of Patent: August 16, 2022
    Assignee: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Travis J. Anderson, Jennifer K. Hite, James C. Gallagher, Karl D. Hobart
  • Patent number: 11342420
    Abstract: Current conducting devices and methods for their formation are disclosed. Described are vertical current devices that include a substrate, an n-type material layer, a plurality of p-type gates, and a source. The n-type material layer disposed on the substrate and includes a current channel. A plurality of p-type gates are disposed on opposite sides of the current channel. A source is disposed on a distal side of the current channel with respect to the substrate. The n-type material layer comprises beta-gallium oxide.
    Type: Grant
    Filed: September 15, 2020
    Date of Patent: May 24, 2022
    Assignee: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Francis J. Kub, Travis J. Anderson, Marko J. Tadjer, Andrew D. Koehler, Karl D. Hobart
  • Patent number: 11227943
    Abstract: A high electron mobility transistor (HEMT) and method of producing the same are provided. The HEMT includes a barrier layer formed on a GaN layer. The HEMT also includes a ZrO2 gate dielectric layer formed by either a ZTB precursor, a TDMA-Zr precursor, or both. The HEMT may also include a recess in the barrier layer in the gate region of the HEMT. The HEMTs may operate in an enhancement mode.
    Type: Grant
    Filed: June 25, 2018
    Date of Patent: January 18, 2022
    Assignee: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Travis J. Anderson, Virginia D. Wheeler, Karl D. Hobart, Francis J. Kub
  • Publication number: 20210389126
    Abstract: An improved method for evaluating GaN wafers. RMS analysis of wafer heights obtained by optical interferometric profilometry is combined with an extreme Studentized deviate (ESD) analysis to obtain a map of the wafer surface that more accurately identifies areas on the surface of a GaN wafer having defects that making those areas unsuitable for fabrication of a vertical electronic device thereon such as bumps and/or pits that can lower the breakdown voltage, increase the on-resistance, and increase the ideality factor.
    Type: Application
    Filed: June 11, 2021
    Publication date: December 16, 2021
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: James C. Gallagher, Travis J. Anderson, Jennifer K. Hite, Karl D. Hobart
  • Publication number: 20210381127
    Abstract: A method for growing polycrystalline diamond films having engineered grain growth and microstructure. Grain growth of a polycrystalline diamond film on a substrate is manipulated by growing the diamond on a nanopatterned substrate having features on the order of the initial grain size of the diamond film. By growing the diamond on such nanopatterned substrates, the crystal texture of a polycrystalline diamond film can be engineered to favor the preferred <110> orientation texture, which in turn enhances the thermal conductivity of the diamond film.
    Type: Application
    Filed: August 24, 2021
    Publication date: December 9, 2021
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Karl D. Hobart, Tatyana I. Feygelson, Marko J. Tadjer, Travis J. Anderson, Andrew D. Koehler, Samuel Graham, JR., Mark Goorsky, Zhe Cheng, Luke Yates, Tingyu Bai, Yekan Wang
  • Publication number: 20210375680
    Abstract: Methods for obtaining a free-standing thick (>5 ?m) epitaxial material layer or heterostructure stack and for transferring the thick epitaxial layer or stack to an arbitrary substrate. A thick epitaxial layer or heterostructure stack is formed on an engineered substrate, with a sacrificial layer disposed between the epitaxial layer and the engineered substrate. When the sacrificial layer is removed, the epitaxial layer becomes a thick freestanding layer that can be transferred to an arbitrary substrate, with the remaining engineered substrate being reusable for subsequent material layer growth. In an exemplary case, the material layer is a GaN layer and can be selectively bonded to an arbitrary substrate to selectively produce a Ga-polar or an N-polar GaN layer.
    Type: Application
    Filed: May 24, 2021
    Publication date: December 2, 2021
    Applicant: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Travis J. Anderson, Marko J. Tadjer, Karl D. Hobart
  • Patent number: 11171055
    Abstract: A method of cleaving includes providing a substrate. Optionally, the substrate includes ?-gallium oxide, hexagonal zinc sulfide, or magnesium selenide. The substrate includes at least one natural cleave plane and a crystallinity. The substrate is cleaved along a first natural cleave plane of the at least one natural cleave plane. The cleaving the substrate along the first natural cleave plane includes the following. A micro-crack is generated in the substrate while maintaining the crystallinity adjacent to the micro-crack by generating a plurality of phonons in the substrate, the micro-crack comprising a micro-crack direction along the first natural cleave plane. The micro-crack is propagated along the first natural cleave plane while maintaining the crystallinity adjacent to the micro-crack. Optionally, generating a micro-crack in the substrate by generating a plurality of phonons in the substrate includes generating the plurality of phonons by electron-hole recombination.
    Type: Grant
    Filed: January 30, 2020
    Date of Patent: November 9, 2021
    Assignee: The Government of the United States of America, as represented by the Secretary of the Navy
    Inventors: Nadeemullah A. Mahadik, Robert E. Stahlbush, Marko J. Tadjer, Karl D. Hobart, Francis J. Kub