Charles R. Eddy

Office of Naval Research

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Co-Authors

Michael A. Mastro

United States Naval Research Laboratory

141

Jennifer K. Hite

United States Naval Research Laboratory

138

D. Kurt Gaskill

United States Naval Research Laboratory

136

Rachael L. Myers‐Ward

United States Naval Research Laboratory

112

Virginia D. Wheeler

United States Naval Research Laboratory

Marko J. Tadjer

United States Naval Research Laboratory

Karl D. Hobart

United States Naval Research Laboratory

Travis J. Anderson

United States Naval Research Laboratory

Fritz J. Kub

United States Naval Research Laboratory

Brenda L. VanMil

DEVCOM Army Research Laboratory

Cooperative Institutions

United States Naval Research Laboratory

256

United States Navy

K Lab (United States)

University of Maryland, College Park

Naval Research Laboratory Electronics Science and Technology Division

Pennsylvania State University

Korea University

American Society For Engineering Education

Boston University

Cornell University

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Structure and Morphology of Inclusions in 4° Offcut 4H-SiC Epitaxial Layers

Journal of Electronic Materials (2011)

Nadeemullah A. Mahadik Robert E. Stahlbush S. B. Qadri O. J. Glembocki Dimitri Alexson

Morphology

Ultraviolet

Strain (injury)

10.1007/s11664-011-1570-8

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Citations (31)

Space-charge-limited currents and trap characterization in coaxial AlGaN/GaN nanowires

Journal of Applied Physics (2011)

Blake S. Simpkins Michael A. Mastro Charles R. Eddy Jennifer K. Hite Pehr E. Pehrsson

This manuscript presents the first observation of the space-charge-limited current (SCLC) conduction mechanism in individual heterostructure nanowires (NWs). This effect is exploited to extract size-dependent carrier densities and to demonstrate surface-dominated behavior for these technologically relevant nanostructures. Mobile carrier densities were shown to increase from 2.5 × 1016 to 5.6 × 1017 cm−3, as NW width decreased from 200 to 50 nm. This size-dependent behavior is a consequence of the increasing influence of near-surface confined carriers as widths decrease. Traps impact the SCLC response and were characterized as an exponential band edge tail with an average characteristic energy of 75 meV. In addition to the specific materials properties extracted, these results further demonstrate the tendency for low-dimensional materials (1D NWs) to exhibit SCLC at much lower injection fluxes compared to their higher dimensional (2D heterostructure field-effect transistors) counterparts.

Charge carrier

Coaxial

Wide-bandgap semiconductor

Depletion region

10.1063/1.3622145

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Citations (35)

Multicycle rapid thermal annealing optimization of Mg-implanted GaN: Evolution of surface, optical, and structural properties

Journal of Applied Physics (2014)

Jordan D. Greenlee Boris N. Feigelson Travis J. Anderson Marko J. Tadjer Jennifer K. Hite

The first step of a multi-cycle rapid thermal annealing process was systematically studied. The surface, structure, and optical properties of Mg implanted GaN thin films annealed at temperatures ranging from 900 to 1200 °C were investigated by Raman spectroscopy, photoluminescence, UV-visible spectroscopy, atomic force microscopy, and Nomarski microscopy. The GaN thin films are capped with two layers of in-situ metal organic chemical vapor deposition -grown AlN and annealed in 24 bar of N2 overpressure to avoid GaN decomposition. The crystal quality of the GaN improves with increasing annealing temperature as confirmed by UV-visible spectroscopy and the full widths at half maximums of the E2 and A1 (LO) Raman modes. The crystal quality of films annealed above 1100 °C exceeds the quality of the as-grown films. At 1200 °C, Mg is optically activated, which is determined by photoluminescence measurements. However, at 1200 °C, the GaN begins to decompose as evidenced by pit formation on the surface of the samples. Therefore, it was determined that the optimal temperature for the first step in a multi-cycle rapid thermal anneal process should be conducted at 1150 °C due to crystal quality and surface morphology considerations.

10.1063/1.4892618

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Citations (39)

Characterization of electron cyclotron resonance plasmas optimized for the deposition of polycrystalline diamond films

Journal of Vacuum Science & Technology A Vacuum Surfaces and Films (1993)

D.L. Youchison Charles R. Eddy B.D. Sartwell

Optical emission spectroscopy, Langmuir probes, and B-field probes have been used to characterize electron cyclotron resonance plasmas used in the deposition of polycrystalline diamond films. These plasmas were generated at 1.33 Pa using selected ratios of CO:H2 and CH4:O2:H2 that produced the highest quality films (i.e., high degree of faceting and an intense Raman peak at 1332 cm−1). Electron temperature, ion density, plasma potential and B-field profiles obtained at optimum growth conditions are presented. The best diamond films were produced on silicon (100) substrates biased to +40 V dc and maintained at a constant temperature of 500 °C. These substrates were placed downstream of an electron cyclotron resonance (ECR) layer (the region of high plasma density created by resonant microwave absorption at the 87.5 mT B-field contour), characterized by a Te near 1 eV and ion densities near 4×1012 cm−3. Actinometry was used to quantify the optical emission spectra. In the CO:H2 system, quality films were obtained for line intensity ratios of Hγ/Ar=4.0, Hγ/C2=1.1, CH/C2=1.9, CO/C2=0.73, and O/C2=0.89. Nearly identical films were produced in the CH4:O2:H2 system, with line intensity ratios of Hγ/Ar=4.2, Hγ/C2=1.2, CH/C2=1.5, CO/C2=0.78, O/C2=0.99. These results indicate that feedgas composition is less important than the critical ratios of C/O/H2 in an ECR plasma.

Electron cyclotron resonance

Langmuir Probe

10.1116/1.578275

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Citations (22)

High-performance 4H-SiC single photon avalanche diode operating at solar blind wavelength

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2007)

Xiaobin Xin Jun Hu Petre Alexandov Jian Hui Zhao Brenda L. VanMil

A 4H-SiC SPAD with an off-mesa bonding pad operating at 280nm is presented in this paper, with a low dark count rate of 14kHz and 27kHz at single photon detection efficiency of 3.3% and 4.5%, respectively. The device has a low breakdown voltage of 117V and a low dark current of 17fA, 49fA and 147fA at 50%, 90%, and 95% of breakdown voltage, respectively. The quantum efficiency is measured to be 28% (32%) at 280nm (270nm) with a UV to visible rejection ratio >1400 (>1600).

Quantum Efficiency

Avalanche diode

Single-photon avalanche diode

Photon flux

10.1117/12.752683

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Citations (6)

Temperature and electric field induced metal-insulator transition in atomic layer deposited VO2 thin films

Solid-State Electronics (2017)

Marko J. Tadjer Virginia D. Wheeler Brian P. Downey Zachary R. Robinson David J. Meyer

Metal–insulator transition

Vanadium Oxide

Torr

10.1016/j.sse.2017.06.018

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Citations (27)

Harmonic Generation in Periodically Oriented Gallium Nitride

S. R. Bowman Christopher G. Brown Jennifer K. Hite Jaime A. Freitas Francis J. Kub

Periodically oriented GaN (PO-GaN) devices have been fabricated and tested in order to obtain quasi-phase matched frequency conversion. This report discusses recent measurements of second harmonic generation resonances and characterization of the PO-GaN devices.

Frequency Conversion

Wide-bandgap semiconductor

Characterization

Harmonic

Harmonic Analysis

10.1364/assl.2016.atu5a.3

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Citations (0)

Effect of Surface Morphology on Diode Performance in Vertical GaN Schottky Diodes

ECS Journal of Solid State Science and Technology (2017)

Jennifer K. Hite Travis J. Anderson Michael A. Mastro Lunet E. Luna James C. Gallagher

The properties of thick GaN layers grown by metal organic chemical vapor deposition on 2'' HVPE substrates were investigated. Although the epilayer is smooth on a microscopic scale with high quality layers as evidenced by X-ray diffraction and photoluminescence, macroscopic morphological variations are observed on the wafer surface. These variations correspond to disparities in leakage current in fabricated Schottky barrier diodes, with rougher macroscopic morphology resulting in increased leakage current.

Morphology

Leakage (economics)

10.1149/2.0221711jss

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Citations (14)

Managing Basal Plane Dislocations in SiC: Perspective and Prospects

Meeting abstracts/Meeting abstracts (Electrochemical Society. CD-ROM) (2012)

D. Kurt Gaskill Rachael L. Myers‐Ward Virginia D. Wheeler R.S. Stahlbush Nadeemullah A. Mahadik

Abstract not Available.

Basal plane

Basal (medicine)

10.1149/ma2012-02/30/2523

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Citations (0)

Nanocrystalline Diamond-Gated AlGaN/GaN HEMT

IEEE Electron Device Letters (2013)

Travis J. Anderson Andrew D. Koehler Karl D. Hobart Marko J. Tadjer Tatyana I. Feygelson

Boron-doped ${\rm p}^{+}$ nanocrystalline diamond (NCD) films are implemented as heat spreading gate contacts to AlGaN/GaN high-electron-mobility transistors. This device demonstrates a reduced ON-resistance, reduced gate leakage, and significantly increased ON-state current density compared with the reference Ni/Au-gated devices from the same wafer. The NCD gate electrode is thermally stable, chemically stable, optically transparent, and places a heat spreading film in direct contact with the gate edge, which is the hottest part of the device.

Nanocrystalline material

Contact resistance

10.1109/led.2013.2282968

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Citations (20)