Author
Eric R. Heller
Other affiliations: University of Alabama in Huntsville, Wright State University, Air Force Research Laboratory ...read more
Bio: Eric R. Heller is an academic researcher from Wright-Patterson Air Force Base. The author has contributed to research in topics: High-electron-mobility transistor & Gallium nitride. The author has an hindex of 24, co-authored 88 publications receiving 2523 citations. Previous affiliations of Eric R. Heller include University of Alabama in Huntsville & Wright State University.
Papers
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01 Jan 2020TL;DR: In this paper, the early development of gallium oxide transistors that led to the most common gallium-oxide device: n-type, depletionmode, metal insulator semiconductor field effect transistor.
Abstract: In this chapter, we describe the early development of gallium oxide transistors that led to the most common gallium oxide device: n-type, depletion-mode, metal insulator semiconductor field effect transistor. We relate the enticing material properties of gallium oxide described in earlier chapters to the requirements in design and fabrication of marketable devices for low-loss power switching and radio frequency applications. A route for device optimization is shown by maximizing electric field in the drift region while reducing parasitic resistance. We analyze the developments that will be required to overcome device-related technical barriers such as achieving low contact resistance, reducing effects of self-heating, and increasing device gain. The chapter concludes with recent research and goals for gallium oxide transistors moving forward with subsequent chapters detailing these topics.
1 citations
01 Jan 2011
TL;DR: In this article, a physics-based finite element model of operation of an AlGaN/GaN HEMT with device geometry in- puts taken from transmission electron microscope cross sections and calibrated by comparison with measured electrical data comprising standard field-effect transistor metrics and less well-known model parameters is presented.
Abstract: We present a physics-based finite-element model of operation of an AlGaN/GaN HEMT with device geometry in- puts taken from transmission electron microscope cross sections and calibrated by comparison with measured electrical data comprising standard field-effect transistor metrics and less well- known model parameters. A variety of electrical outputs from the model are compared to experiment, and the level of agreement is reported. Index Terms—Device model, field-effect transistor (FET), GaN, GaN/AlGaN, high-electron mobility transistor (HEMT), model calibration, model characterization, modulation-doped field effect transistor (MODFET).
1 citations
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24 Apr 2018
TL;DR: In this paper, a method of evaluating localized degradation of a III-V compound semiconductor was proposed, which includes preparing first and second III-v compound semiconductors and irradiating and then electrically testing.
Abstract: A method of evaluating localized degradation of a III-V compound semiconductor. The method includes preparing first and second III-V compound semiconductors. The second III-V compound semiconductor that is similar to the first III-V compound semiconductor and further comprises a shield layer that is configured to alter exposed portions of channels of the second III-V compound semiconductor. The first and second III-V compound semiconductors and irradiated and then electrically tested. Results of the electrical testing of the first and second III-V compound semiconductors are compared.
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TL;DR: In this article, the microstructural response of gallium nitride (GaN) films, grown by metal-organic chemical vapor deposition, was studied as a function of applied electrical field.
Abstract: Microstructural response of gallium nitride (GaN) films, grown by metal-organic chemical vapor deposition, was studied as a function of applied electrical field. In-situ transmission electron microscopy showed sudden change in the electron diffraction pattern reflecting domain switching at around 20 V bias, applied perpendicular to the polarization direction. No such switching was observed for thicker films or for the field applied along the polarization direction. This anomalous behavior is explained by the nanoscale size effects on the piezoelectric coefficients of GaN, which can be 2–3 times larger than the bulk value. As a result, a large amount of internal energy can be imparted in 100 nm thick films to induce domain switching at relatively lower voltages to induce such events at the bulk scale.
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01 May 1993
TL;DR: Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems.
Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.
29,323 citations
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28,685 citations
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2,147 citations
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TL;DR: The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed in this article.
Abstract: Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics, solar blind UV photodetectors, solar cells, and sensors with capabilities beyond existing technologies due to its large bandgap. It is usually reported that there are five different polymorphs of Ga2O3, namely, the monoclinic (β-Ga2O3), rhombohedral (α), defective spinel (γ), cubic (δ), or orthorhombic (e) structures. Of these, the β-polymorph is the stable form under normal conditions and has been the most widely studied and utilized. Since melt growth techniques can be used to grow bulk crystals of β-GaO3, the cost of producing larger area, uniform substrates is potentially lower compared to the vapor growth techniques used to manufacture bulk crystals of GaN and SiC. The performance of technologically important high voltage rectifiers and enhancement-mode Metal-Oxide Field Effect Transistors benefit from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. However, the absence of clear demonstrations of p-type doping in Ga2O3, which may be a fundamental issue resulting from the band structure, makes it very difficult to simultaneously achieve low turn-on voltages and ultra-high breakdown. The purpose of this review is to summarize recent advances in the growth, processing, and device performance of the most widely studied polymorph, β-Ga2O3. The role of defects and impurities on the transport and optical properties of bulk, epitaxial, and nanostructures material, the difficulty in p-type doping, and the development of processing techniques like etching, contact formation, dielectrics for gate formation, and passivation are discussed. Areas where continued development is needed to fully exploit the properties of Ga2O3 are identified.
1,535 citations
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Sandia National Laboratories1, University of California, Davis2, Massachusetts Institute of Technology3, Cornell University4, United States Army Research Laboratory5, Ohio State University6, University of California, Santa Barbara7, Boston University8, North Carolina State University9, Purdue University10, Georgia Institute of Technology11, Michigan State University12, Air Force Research Laboratory13, National Institute of Information and Communications Technology14, University of South Carolina15, United States Naval Research Laboratory16, Arizona State University17, University of Illinois at Urbana–Champaign18, Vanderbilt University19
TL;DR: The UWBG semiconductor materials, such as high Al‐content AlGaN, diamond and Ga2O3, advanced in maturity to the point where realizing some of their tantalizing advantages is a relatively near‐term possibility.
Abstract: J. Y. Tsao,* S. Chowdhury, M. A. Hollis,* D. Jena, N. M. Johnson, K. A. Jones, R. J. Kaplar,* S. Rajan, C. G. Van de Walle, E. Bellotti, C. L. Chua, R. Collazo, M. E. Coltrin, J. A. Cooper, K. R. Evans, S. Graham, T. A. Grotjohn, E. R. Heller, M. Higashiwaki, M. S. Islam, P. W. Juodawlkis, M. A. Khan, A. D. Koehler, J. H. Leach, U. K. Mishra, R. J. Nemanich, R. C. N. Pilawa-Podgurski, J. B. Shealy, Z. Sitar, M. J. Tadjer, A. F. Witulski, M. Wraback, and J. A. Simmons
785 citations