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In this letter, fin-shape tri-gate $\beta$-Ga$_{2}$O$_{3}$ lateral MESFETs are demonstrated with a high power figure of merit of 0.95 GW/cm$^{2}$ - a record high for any $\beta$-Ga$_{2}$O$_{3}$ transistor to date. A low-temperature undoped buffer-channel stack design is developed which demonstrates record high Hall and drift electron mobilities in doped $\beta$-Ga$_{2}$O$_{3}$ channels allowing for low ON resistances R$_{ON}$ in $\beta$-Ga$_{2}$O$_{3}$ MESFETs. Fin-widths (W$_{fin}$) were 1.2-1.5 $\mu$m and there were 25 fins (N$_{fin}$) per device with a trench depth of $\sim$1$\mu$m. A $\beta$-Ga$_2$O$_3$ MESFET with a source-drain length of 6.4 $\mu$m exhibits a high ON current (187 mA/mm), low R$_{ON}$ (20.5 $\Omega$.mm) and a high average breakdown field (4.2 MV/cm). All devices show very low reverse leakage until catastrophic breakdown for breakdown voltages scaled from 1.1kV to $\sim$3kV. This work demonstrates the potential of channel engineering in improving $\beta$-Ga$_{2}$O$_{3}$ device performance toward lower conduction losses for low-to-medium voltage applications., Comment: 4 pages, 5 pages

We demonstrate over 3 kV gate-pad-connected field plated (GPFP) $\beta $ -Ga2O3 lateral MESFETs with high lateral figures of merit (LFOM) using metalorganic vapor phase epitaxy (MOVPE) grown channel layers and regrown ohmic contact layers. Using an improved low-temperature MOVPE selective area epitaxy process, we show that a total contact resistance to the channel as low as $1.4~\Omega $ .mm can be achieved. The GPFP design adopted here using plasma-enhanced chemical vapor deposited (PECVD) SiNx dielectric and SiNx/SiO2 wrap-around passivation exhibits up to ~14% improved $\text{R}_{{\text {ON}}}$ , up to ~70% improved breakdown voltage ( $\text{V}_{{\text {BR}}}= \text {V}_{{\text {DS}}}-\text {V}_{{\text {GS}}}$ ) resulting in up to $3\times $ higher LFOM compared to the non-FP $\beta $ -Ga2O3 lateral MESFETs. The $\text{V}_{{\text {BR}}}$ (~2.5 kV) and LFOM (355 MW/cm2) measured simultaneously in our GPFP $\beta $ -Ga2O3 lateral MESFET (with $\text{L}_{{\text {GD}}} = {10}\mu \text{m}$ ) is the highest value achieved in any depletion-mode $\beta $ -Ga2O3 lateral device to date.

We report on the realization of record low resistance Ohmic contacts to MOVPE-grown heavily Si-doped $\beta$-Ga$_2$O$_3$ and $\beta$-(Al$_x$Ga$_1-x$)$_2$ O$_3$ epitaxial films. Transfer length measurement (TLM) patterns were fabricated on the heavily Si-doped homoepitaxial $\beta$-Ga$_2$O$_3$ films with electron concentration (n) ranging from 1.77 to 3.23e20 cm^-3. Record low specific contact resistance and total contact resistance (Rc) of 1.62e-7 Ohm.cm^2 and 0.023 Ohm.mm were realized for $\beta$-Ga$_2$O$_3$: Si films with n > 3e20 cm^-3. TLM structures were also fabricated on heavily Si doped coherently strained $\beta$-(Al$_x$Ga$_1-x$)$_2$ O$_3$ (x=12%, 17% and 22%) films. The film with 12% Al composition (n=1.23e20 cm^-3) showed \r{ho}c of 5.85e-6 Ohm.cm^2, but it increased to 2.19e-4 Ohm.cm^2 for a layer with a 22% Al composition. Annealing the samples post metal deposition has generally led to a decrease in contact resistance, but for high Al content $\beta$-(Al$_x$Ga$_1-x$)$_2$ O$_3$, the contact resistance did not change significantly after the annealing process. The low contact resistance values measured in this work are very promising for the fabrication of high frequency power devices.

We report a vertical β-Ga2O3 Schottky barrier diode (SBD) with BaTiO3 as field plate oxide on a low doped thick epitaxial layer exhibiting 2.1 kV breakdown voltage. A thick drift layer of 11 μm with a low effective doping concentration of 8 × 1015 cm–3 is used to achieve high breakdown voltage. Using the high-k dielectric with a dielectric constant of 248, the breakdown voltage increases from 816 V for the non-field-plated SBD to 2152 V (>2× improvement) for the field-plated SBD without compromising the on-state performance. The diode dimensions are varied to analyze the effect of edge high-field related leakage with reverse bias and also the effect of current spreading during forward operation. Very uniform distribution of breakdown voltages of 2152 ± 20 V are observed for the diode diameters from 50 to 300 μm for the field-plated SBDs. The on and off state power losses are also analyzed and compared with the non-field-plated devices and the switching losses are estimated analytically.

β-Ga2O3 metal–semiconductor field-effect transistors are realized with superior reverse breakdown voltages (V BR) and ON currents (I DMAX). A sandwiched SiN x dielectric field plate design is utilized that prevents etching-related damage in the active region and a deep mesa-etching was used to reduce reverse leakage. The device with L GD = 34.5 μm exhibits an I DMAX of 56 mA mm−1, a high I ON/I OFF ratio >108 and a very low reverse leakage until catastrophic breakdown at ∼4.4 kV. A power figure of merit (PFOM) of 132 MW cm−2 was calculated for a V BR of ∼4.4 kV. The reported results are the first >4 kV class Ga2O3 transistors to surpass the theoretical unipolar FOM of silicon.

In this work, bulk Czochralski-grown single crystals of 10 mol. % Al2O3 alloyed β-Ga2O3—monoclinic 10% AGO or β-(Al0.1Ga0.9)2O3—are obtained, which show +0.20 eV increase in the bandgap compared with unintentionally doped β-Ga2O3. Further, growths of 33% AGO—β-(Al0.33Ga0.67)2O3—and 50% AGO—β-(Al0.5Ga0.5)2O3 or β-AlGaO3—produce polycrystalline single-phase monoclinic material (β-AGO). All three compositions are investigated by x-ray diffraction, Raman spectroscopy, optical absorption, and 27Al nuclear magnetic resonance (NMR). By investigating single phase β-AGO over a large range of Al2O3 concentrations (10–50 mol. %), broad trends in the lattice parameter, vibrational modes, optical bandgap, and crystallographic site preference are determined. All lattice parameters show a linear trend with Al incorporation. According to NMR, aluminum incorporates on both crystallographic sites of β-Ga2O3, with a slight preference for the octahedral (GaII) site, which becomes more disordered with increasing Al. Single crystals of 10% AGO were also characterized by x-ray rocking curve, transmission electron microscopy, purity (glow discharge mass spectroscopy and x-ray fluorescence), optical transmission (200 nm–20 μm wavelengths), and resistivity. These measurements suggest that electrical compensation by impurity acceptor doping is not the likely explanation for high resistivity, but rather the shift of a hydrogen level from a shallow donor to a deep acceptor due to Al alloying. Bulk crystals of β-(Al0.1Ga0.9)2O3 have the potential to be ultra-wide bandgap substrates for thin film growth, with a lattice parameter that may even allow higher Al concentration β-Ga2O3 single crystal thin films to be grown.

I was alerted to a recent book published in 2015, which claims science and religion are incompatible, and in “a war for understanding.” Now that’s drama! Due to this dramatic statement in such a re...

Richard Feynman, a 1965 Nobel Prize winner in physics, quoting an unknown philosopher, said: “It is necessary for the very existence of science that the same conditions always produce the same results.” And Feynman's reply: “Well, they don't.” Double-slit experiments with both slits open and the wave interference pattern created by electrons falling on a screen behind the slits speak volumes to those two statements and the interpretive problem created by the non-deterministic behavior of microscopic matter. Quantum mechanics (QM) with its successes over the last 85 years has created the information age, and with insights into nature has given humans an economy concentrated with products based on quantum technology. All this even with questions about the fundamental aspects of measurement in the quantum world still being debated! Discussing the measurement aspect of QM does not require a physics background where physics scholars join other scholarly disciplines engaged in gaining knowledge about th...

The search for the Higgs boson has been like the search of a pirate for buried gold. Like the pirate, the physicist has a map, a conceptual map—the Standard Model (SM) made up of mathematical formulas. Without the Higgs boson in the SM, fundamental particles would be massless. Where could the mass mechanism be? The conceptual map pointed in the right direction. On July 4, 2012 the pirates found their treasure with the help of the Large Hadron Collider (LHC) at CERN. In this article a physicist and theologian ask: could this be critical realism (CR) at work? Could CR constitute a set of presuppositions shared by both physicists and theologians who cannot see the object of their inquiry but employ conceptual models that presuppose the reality of its referent? What role could shared CR play in the creative mutual interaction between science and theology?

Mutual respect and understanding between the world's religions has become increasingly necessary in a global society where peace can be tenuous. This article will concentrate on challenges for Christianity in relationship with other world religions. Can interreligious dialogue benefit from what we learn from the dialogue 1 between science and theology? Yes. 2 The science–theology dialogue is part of the ongoing effort to bridge 3 the intellectual divide between the discoveries of natural science that have made our lives in the material world better, and interpretations and understandings in the various faith traditions that have given meaning and value to our living in the material world.

Heparin is widely used in a variety of settings for prevention and treatment of thromboembolic events. Data from a number of sources indicate that it is also one of the drugs most frequently associated with adverse events and medication errors, many of which are serious. National media attention has focused on recent events involving heparin and The Joint Commission has included heparin in its 2009 National Patient Safety Goal to reduce patient harm from anticoagulants. Heparin safety is on the national agenda and health care organizations are struggling to improve it. Health care providers in clinical, management, and executive roles must work together to improve heparin safety. Over 40 anticoagulation experts and practitioners came together in San Diego on March 13 through 14, 2008 to share information, offer perspectives, and address issues on the topic improving heparin safety. These individuals represented The Joint Commission, United States Pharmacopoeia, the Institute for Safe Medical Practices, academic institutions, large health care systems, and small hospitals who participated in a day and a half of presentations and round-table discussions. This article summarizes 21 presentations with a primary focus on types and frequency of heparin errors as well as identified opportunities to improve heparin safety. The conference was sponsored by Cardinal Health's Center for Safety and Clinical Excellence.

The Department of Energy has given Sandia full responsibility for the complete life cycle (cradle to grave) of all nuclear weapon parachutes. Sandia National Laboratories is initiating development of a complete numerical simulation of parachute performance, beginning with parachute deployment and continuing through inflation and steady state descent. The purpose of the parachute performance code is to predict the performance of stockpile weapon parachutes as these parachutes continue to age well beyond their intended service life. A new massively parallel computer will provide unprecedented speed and memory for solving this complex problem, and new software will be written to treat the coupled fluid, structure and trajectory calculations as part of a single code. Verification and validation experiments have been proposed to provide the necessary confidence in the computations.

A study to determine the incidence of alkaline reflux gastritis in forty postoperative duodenal ulcer patients has been presented. Since the majority of patients had evidence of gastritis, the precise role that gastritis plays in the production of symptoms is discussed but needs further clarification. It is suggested that the presence of gastritis may only represent an incidental or associated finding in many patients presenting with symptoms presumably characteristics of alkaline reflux gastritis.

Ab initio self‐consistent‐field calculations have been carried out on the permanganate ion using large Gaussian basis sets. The ground state as well as a number of interesting excited states have been treated. Calculations for the neutral and double negative species derived from the permanganate ion are also given.

A new technique for the determination of atomic valence states and their energies has been developed and applied to the water molecule and hydroxyl radical. This method is applicable to valence-bond studies involving a large number of resonance structures rather than simply a one structure perfect pairing approach. The original basis of resonance structures is transformed into a basis of approximate composite functions which are orthogonal and non-interacting for the separated atoms. The equilibrium molecular eigenfunction is analyzed in terms of the composite functions by means of structure projections. A description of the valence states and the promotional energies of each of the component atoms in H2O and OH is obtained.

We show that the observed beam spot consists of accumulated carbon. The accumulation is the same on the front and back surface of a thin target, and is proportional to the bombardment time at current densities greater than ? 2?A/cm2. In our energy range of investigation (100-300 keV), the accumulation rate is independent of energy, but does vary with the temperature of the target. For targets at ? 15°C, the accumulation rate for an oil diffusion pumped target chamber is ? 2?g/cm2-hr or 2A/min, which corresponds to a retention of one carbon atom per incident proton. Cooling a shield surrounding the target, or heating the target to 150°C, reduces this accumulation rate by an order of magnitude.

1. 1. Seven hundred fifty-seven thyroid operations were performed during the eight-year period, 1949 through 1956, at the Palo Alto Hospital, Palo Alto, California. 2. 2. Seventy-seven (seventy-five female patients, two male) of the surgical specimens showed diffuse lymphocytic thyroiditis (10.1 per cent). 3. 3. Lymphocytic thyroiditis occurred in relatively “pure” form in forty-three patients, in association with adenomas in thirty-two patients, and in association with carcinoma in two patients. Cases in which the lymphocytic infiltrate was of a reactive type or of focal distribution were excluded from the data. 4. 4. Only a small proportion of the cases showed follicular and epithelial alterations of the thyroid gland usually considered diagnostic of struma lymphomatosa (Hashimoto's disease). 5. 5. Comparison between the cases of characteristic Hashimoto's variety with all others showed no significant differences in age group, sex incidence, clinical findings, preoperative diagnosis or postoperative course. 6. 6. The relative age distribution of patients with cystic mastitis is similar to those with lymphocytic thyroiditis. 7. 7. Thirty-three carcinomas were found in the 757 surgical specimens.

With apparent inoperable hepatic cell carcinoma, knowledge of adequate venous outflow from tumor-free liver tissue permits extensive resection with long survival.

A presentation of the factorization procedure that explicitly demonstrates the simple algebraic techniques without resorting to operator shorthand; the harmonic oscillator is used to illustrate thi...

Compares the polynomial method with the factorization method to assess which is more heuristically advantageous in light of the mathematical problems students often have.

Excerpt Benign neoplasms of the small intestine are not common, and hemangiomas, although frequently found elsewhere in the body, are rare in this area (1). River, Silverstein, and Tope (2), in a r...