Karl D. Hobart

U.S. Naval Research Laboratory

  • Exploring the capability of Hyperspectral Electroluminescence for process monitoring in vertical GaN devices

    Karl D. Hobart, U.S. Naval Research Laboratory
    Mona Ebrish, Vanderbilt University, Nashville, TN
    Travis J. Anderson, U.S. Naval Research Laboratory
    James Gallagher, U.S. Naval Research Laboratory
    Joseph Spencer, U.S. Naval Research Laboratory, Washington, DC, USA, Virginia Tech
    Jennifer Hite, U.S. Naval Research Laboratory
    Michael Mastro, U.S. Naval Research Laboratory

    GaN is a promising material for more efficient high frequency and high voltage power switching. However, GaN still is not the common material for power electronics due to immature substrate, homoepitaxial growth, and processing technology. Electroluminescence is a promising method to predict failure points due to high field stress, which can assist in the separation of inherent defects stemming from substrate quality, and from process-induced defects as well as identify problems related to proper edge termination design. In this work, we compare the Electroluminescence signatures of devices on inhomogeneous substrates to DC I-V behavior to demonstrate the utility of the technique for process monitoring.

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  • 13.1 High Aspect Ratio Vias in Silicon Carbide Etched by Inductively-Coupled Plasma

    Marko Tadjer, U.S. Naval Research Laboratory
    Lunet Luna, U.S. Naval Research Laboratory
    Eugene Imhoff, Naval Research Laboratory
    Karl D. Hobart, U.S. Naval Research Laboratory
    Fritz Kub, Naval Research Laboratory
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  • 16.3 Evaluation of GaN Device Structures on 150 mm GaN on Engineered Substrates

    Karl D. Hobart, U.S. Naval Research Laboratory
    Andrew Koehler, Naval Research Laboratory
    Anindya Nath, George Mason University
    Jennifer Hite, U.S. Naval Research Laboratory
    N. Mahadik, U.S. Naval Research Laboratory
    Fritz Kub, Naval Research Laboratory
    Ozgur Aktas, QROMIS, USA
    Vladimir Odnoblyudov, QROMIS, USA
    Cem Basceri, QROMIS, USA
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  • 18.2 Engineering PECVD SiN Passivation Layers to Enable AlGaN/GaN HEMTs with Low Leakage, Low Current Collapse and High Breakdown Voltage

    Andrew Koehler, Naval Research Laboratory
    Marko Tadjer, U.S. Naval Research Laboratory
    Karl D. Hobart, U.S. Naval Research Laboratory
    Fritz Kub, Naval Research Laboratory
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  • 18.3 Threshold Voltage Control by Tuning Charge in ZrO2 Gate Dielectrics for Normally-off AlGaN/GaN MOS-HEMTs

    Virginia Wheeler, U.S. Naval Research Laboratory
    David Shahin, University of Maryland
    Marko Tadjer, U.S. Naval Research Laboratory
    Lunet Luna, U.S. Naval Research Laboratory
    Andrew Koehler, Naval Research Laboratory
    Karl D. Hobart, U.S. Naval Research Laboratory
    Francis Kub, U.S. Naval Research Laboratory
    Charles Eddy, US Naval Research Laboratory
    Jr., Naval Research Laboratory
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  • 20.5 Characterization of ALD High-k Dielectrics in GaN and Ga2O3 Metal-Oxide-Semiconductor Systems

    David Shahin, University of Maryland
    Virginia Wheeler, U.S. Naval Research Laboratory
    Marko Tadjer, U.S. Naval Research Laboratory
    Lunet Luna, U.S. Naval Research Laboratory
    Andrew Koehler, Naval Research Laboratory
    Karl D. Hobart, U.S. Naval Research Laboratory
    Charles Eddy, US Naval Research Laboratory
    Jr., Naval Research Laboratory
    Fritz Kub, Naval Research Laboratory
    Aris Christou, University of Maryland-College Park
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  • 5.3 Influence of Substrate Removal on the Electrothermal Characteristics of AlGaN/GaN Membrane High Electron Mobility Transistors

    Marko Tadjer, U.S. Naval Research Laboratory
    Peter Raad, TMX Scientific and Southern Methodist University
    Tatyana Feygelson, Naval Research Laboratory
    Andrew Koehler, Naval Research Laboratory
    Bradford Pate, Naval Research Laboratory
    Karl D. Hobart, U.S. Naval Research Laboratory
    Fritz Kub, Naval Research Laboratory
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  • 9.1 Improvements in the Annealing of Ion Implanted III-Nitride Materials and Related Devices

    Jordan Greenlee, NRC Postdoctoral Fellow Residing at the Naval Research Laboratory
    Boris Feigelson, Naval Research Laboratory
    Jennifer Hite, U.S. Naval Research Laboratory
    Karl D. Hobart, U.S. Naval Research Laboratory
    Francis Kub, U.S. Naval Research Laboratory
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  • 10b.4 Reliability Assessment of Thermally-Stable Gate Materials for AlGaN/GaN HEMTs

    David Shahin, University of Maryland
    Jordan Greenlee, NRC Postdoctoral Fellow Residing at the Naval Research Laboratory
    Andrew Koehler, Naval Research Laboratory
    Virginia Wheeler, U.S. Naval Research Laboratory
    Marko Tadjer, U.S. Naval Research Laboratory
    Tatyana Feygelson, Naval Research Laboratory
    Bradford Pate, Naval Research Laboratory
    Jennifer Hite, U.S. Naval Research Laboratory
    Karl D. Hobart, U.S. Naval Research Laboratory
    Charles Eddy, US Naval Research Laboratory
    Jr., Naval Research Laboratory
    Francis Kub, U.S. Naval Research Laboratory
    Aris Christou, University of Maryland-College Park
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  • 11.2 Effect of Surface Passivation on Current Collapse of Proton-Irradiated AlGaN/GaN HEMTs

    Andrew Koehler, Naval Research Laboratory
    Marko Tadjer, U.S. Naval Research Laboratory
    Bradley Weaver, U.S. Naval Research Laboratory
    Jordan Greenlee, NRC Postdoctoral Fellow Residing at the Naval Research Laboratory
    David Shahin, University of Maryland
    Karl D. Hobart, U.S. Naval Research Laboratory
    Francis Kub, U.S. Naval Research Laboratory
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  • 11.5 Optimization of AlGaN/GaN HEMT SiN Passivation by Mixed Frequency PECVD

    Marko Tadjer, U.S. Naval Research Laboratory
    Andrew Koehler, Naval Research Laboratory
    Charles Eddy, US Naval Research Laboratory
    Jr., Naval Research Laboratory
    Karl D. Hobart, U.S. Naval Research Laboratory
    Fritz Kub, Naval Research Laboratory
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  • 8.3.2023 Heterogeneous Integration of Gallium Nitride HEMTs with Single Crystal Diamond Substrates via Micro-transfer Printing for Thermal Management

    James Spencer Lundh, National Research Council Postdoctoral Fellow, Residing at NRL
    Andy Xie, Qorvo
    Shawn Mack, U.S. Naval Research Laboratory
    D. Scott Katzer, U.S. Naval Research Laboratory
    Marko J. Tadjer, U.S. Naval Research Laboratory
    Travis J. Anderson, U.S. Naval Research Laboratory
    Brian Downey, US Naval Research Laboratory
    David J Meyer, U.S. Naval Research Laboratory, Washington, DC

    8.3.2023 Paper 2023 Lundh CS Mantech extended abstract v6

  • 9.4.2023 Scalable Manufacturing of Planar, Large-Area 1.2kV and 3.3kV Vertical GaN PiN Diodes

    Alan Jacobs, U.S. Naval Research Laboratory, Washington DC
    Mona Ebrish, NRC Postdoc Fellow Residing at the U.S. Naval Research Laboratory
    James Gallagher, U.S. Naval Research Laboratory
    Marko J. Tadjer, U.S. Naval Research Laboratory
    James Spencer Lundh, National Research Council Postdoctoral Fellow, Residing at NRL
    Jennifer K. Hite, Naval Research Laboratory
    N. Mahadik, U.S. Naval Research Laboratory
    Robert Kaplar, Sandia National Labs, Albuquerque, NM
    O. Aktas, Sandia National Labs, Albuquerque, NM

    9.4.2023_Anderson

  • 10.5.2023 Accuracy of Machine Learning Models on Predicting the Properties of Vertical GaN Diodes

    James Gallagher, U.S. Naval Research Laboratory
    Michael A. Mastro, U.S. Naval Research Laboratory
    Mona Ebrish, Vanderbilt University, Nashville, TN
    Alan Jacobs, U.S. Naval Research Laboratory, Washington DC
    Brendan. P. Gunning, Sandia National Labs, Albuquerque, NM
    Robert Kaplar, Sandia National Labs, Albuquerque, NM

    10.5.2023_Gallagher

  • 11.4.2023 Nanocrystalline Diamond-Capped β-(AlxGa1-x)2O3/Ga2O3 Heterostructure FieldEffect Transistor

    Hannah N. Masten, National Research Council Postdoctoral Fellow, Residing at NRL
    James Spencer Lundh, National Research Council Postdoctoral Fellow, Residing at NRL
    Tatyana Feygelson, Naval Research Laboratory
    Joseph Spencer, U.S. Naval Research Laboratory, Washington, DC, USA, Virginia Tech
    Tatyana I. Feygelson, American Society for Engineering Education, United States Naval Research Lab. Universidad Politecnica de Madrid
    Jennifer K. Hite, Naval Research Laboratory
    Daniel Pennachio, U.S. Naval Research Laboratory, Washington DC
    Alan Jacobs, U.S. Naval Research Laboratory, Washington DC
    Boris Feygelson, U.S. Naval Research Laboratory
    Kohei Sasaki, Novel Crystal Technology
    Akito Kuramata, Novel Crystal Technology, Inc
    Pai-Ying Liao, Purdue University
    Peide Ye, Purdue University
    Bradford Pate, Naval Research Laboratory
    Travis J. Anderson, U.S. Naval Research Laboratory
    Marko J. Tadjer, U.S. Naval Research Laboratory

    11.4.2023_Masten- NCD HFET- 2023 CS Mantech – final paper_hnm

  • 15.3.2023 Characterization of Nitridated Ga2O3 for GaN-on-Ga2O3 Power Device Applications

    Matthew Landi, University of Illinois at Urbana-Champaign
    Frank Kelly, University of Illinois at Urbana-Champaign
    Riley Vesto, University of Illinois at Urbana-Champaign
    Marko J. Tadjer, U.S. Naval Research Laboratory
    Kyekyoon Kim, University of Illinois at Urbana-Champaign

    15.3.2023_Landi-KK_CSMantech2023_ExtendedAbstract_CharacterizationOfNitridatedGa2O3

  • 15.5.2023 Scalable Selective Area Doping for Manufacturing of Planar Vertical Power GaN Devices

    Alan Jacobs, U.S. Naval Research Laboratory, Washington DC
    Boris N. Feigelson, Naval Research Laboratory
    Jennifer Hite, U.S. Naval Research Laboratory
    Joseph Spencer, U.S. Naval Research Laboratory, Washington, DC, USA, Virginia Tech
    Prakash Pandey, University of Toledo, Toledo OH
    Daniel G. Georgiev, University of Toledo, Toledo OH
    Raghav Khanna, University of Toledo, Toledo OH
    Marko J. Tadjer, U.S. Naval Research Laboratory
    Travis J. Anderson, U.S. Naval Research Laboratory

    15.5.2023 Alan Jacobs CS Mantech ExtAbstract_submission2

  • Formation of Diamond Superjunctions to Enable GaN-Based Super-Lattice Power Amplifiers with Diamond Enhanced Superjunctions (SPADES)

    Geoffrey Foster, Jacobs Inc., Washington DC
    Tatyana Feygelson, Naval Research Laboratory
    James Gallagher, ASEE Postdoctoral Fellow Residing at NRL
    Josephine Chang, Northrop Grumman
    Shamima Afroz, Northrop Grumman
    Ken Nagamatsu, Northrop Grumman
    Robert Howell, Northrop Grumman
    Fritz Kub, Naval Research Laboratory

    The super-lattice power amplifier with diamond enhanced superjunctions (SPADES) is a device that incorporates nanocrystalline diamond superjunctions into the super-lattice castellated field effect transistor (SLCFET), to improve breakdown voltage. A diamond superjunction is formed with p-type nanocrystalline diamond to balance mutual depletion between the two-dimensional electron gas superlattices and the doped diamond in order to reduce the peak electric field in the drain access region.  Formation of the diamond superjunction presents several challenges, such as managing diamond conformality, strain, and control over p-type doping.  Optimization of diamond growth led to conformal films, with low stress, and linear dependence hole concentration from p-type doping, suitable for the SPADES device.

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  • 11.3.2023 Structural and Electrical Characterization of Schottky Barrier Diodes on 100 mm HVPE β-Ga2O3 Epiwafer Technology

    Marko J. Tadjer, U.S. Naval Research Laboratory
    James Gallagher, ASEE Postdoctoral Fellow Residing at NRL
    N. Mahadik, U.S. Naval Research Laboratory
    Hannah N. Masten, National Research Council Postdoctoral Fellow, Residing at NRL
    James Spencer Lundh, National Research Council Postdoctoral Fellow, Residing at NRL
    Akito Kuramata, Novel Crystal Technology, Inc

    11.3.2023_CS_MANTECH-2023_extended-abstract_Tadjer final

  • 18.15.2023 Characterization of Optically Modulated Semi-Insulating GaN Photoconductive Semiconductor Switches

    Geoffrey Foster, Jacobs Inc., Washington DC
    Andrew Koehler, Naval Research Laboratory
    Karl D. Hobart, U.S. Naval Research Laboratory
    Sadab Mahmud, University of Toledo, Toledo OH
    Samuel Atwimah, University of Toledo, Toledo OH
    Raghav Khanna, University of Toledo, Toledo OH
    Travis J. Anderson, U.S. Naval Research Laboratory

    18.15.2023 Foster – CSMANTECH2023 v2

  • 14.9 Fabrication of True Vertical GaN Schottky Diodes from 150 mm Engineered Substrates

    Lunet E. Luna, NRC Postdoctoral Fellow Residing at NRL
    Marko J. Tadjer, U.S. Naval Research Laboratory
    Ozgur Aktas, QROMIS, USA
    Fritz J. Kub, U.S. Naval Research Laboratory
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