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Effects of Incident Angle on Single-Event Leakage Current Degradation in Heavy-Ion Irradiated 1800 v and 4500 v SiC Power MOSFETs

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IEEE Transactions on Nuclear Science 2025年

作者： Sengupta, A. Martinella, C. Ball, D.R. Niskanen, K. Senarath, A.S. Islam, S. Harris, P.M. Hutson, J.M. Osheroff, J.M. Sternberg, A.L. Kettunen, H. Kosier, S.L. Grossner, U. Javanainen, A. Galloway, K.F. Schrimpf, R.D. Witulski, A.F. Zürich8092 Switzerland Vanderbilt University Interdisciplinary Materials Science Program NashvilleTN37235 United States Lipscomb University Electrical and Computer Engineering Department NashvilleTN37204 United States NASA/GSFC Code 561.4 GreenbeltMD20771 United States Vanderbilt University Electrical Engineering and Computer Science Department B 351825 NashvilleTN37235 United States University of Jyväskylä Department of Physics Jyväskylä40014 Finland

Experimental heavy-ion responses of two variants of SiC power MOSFETs are evaluated. The devices have similar epitaxial thickness but different doping. The higher doping in the epitaxial region results in lower breakdown voltage, and typically leads to a lower threshold drain voltage at which single-event leakage current (SELC) occurs. Furthermore, the heavy-ion-induced SELC degradation in the drain and gate currents of the SiC MOSFETs exhibit a strong dependence on the heavy-ion's angle of incidence. The devices' behavior significantly alters when irradiated with heavy-ions at different incident angles under the same fixed bias and total fluence, as also confirmed by 3-D Technology Computer Aided Design (TCAD) simulations. © 1963-2012 IEEE.

关键词： Power MOSFET

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Fate of multipolar physics in 5d2 double perovskites

arXiv

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arXiv 2023年

作者： Rayyan, Ahmed Liu, Xiaoyu Kee, Hae-Young Department of Physics University of Toronto TorontoONM5S 1A7 Canada Department of Materials Science and Engineering University of Washington SeattleWA98195 United States CIFAR Program in Quantum Materials Canadian Institute for Advanced Research TorontoONM5G 1M1 Canada

In a cubic environment, the ground state of spin-orbit coupled 5d2 ions is a non-Kramers Eg doublet, which hosts quadrupole and octupole moments. A series of 5d2 osmium double perovskites Ba2MOsO6 (M = Mg, Ca, Zn, Cd) have recently been proposed to exhibit multipolar orders. We investigate the structural properties of these materials using ab-initio calculations and find that the cubic structure is unstable for the Cd compound while the Mg, Ca, and Zn materials retain Fm3¯m symmetry. We show that Ba2CdOsO6 favours a rhombohedral R3¯ structure characterized by a−a−a− octahedral tiltings as indicated by unstable T1g phonon modes. Trigonal distortions split the excited T2g triplet into an Eg′ doublet and an Ag singlet, which may cross energy levels with the Eg doublet and suppress the multipolar physics. We find a window where Eg remains the lowest energy state under trigonal distortion, enabling the emergence of multipole phases in non-cubic crystal environments. © 2023, CC BY.

关键词： Barium compounds

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Terahertz spin dynamics in rare-earth orthoferrites

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Photonics Insights 2022年第2期1卷 1-56页

作者： Xinwei Li Dasom Kim Yincheng Liu Junichiro Kono Department of Physics California Institute of TechnologyPasadenaUSA Department of Electrical and Computer Engineering Rice UniversityHoustonUSA Applied Physics Graduate Program Smalley-Curl InstituteRice UniversityHoustonUSA Department of Physics and Astronomy Rice UniversityHoustonUSA Department of Materials Science and NanoEngineering Rice UniversityHoustonUSA

Recent interest in developing fast spintronic devices and laser-controllable magnetic solids has sparked tremendous experimental and theoretical efforts to understand and manipulate ultrafast dynamics in *** of spin dynamics in the terahertz(THz)frequency range are particularly important for elucidating microscopic pathways toward novel device ***,we review THz phenomena related to spin dynamics in rare-earth orthoferrites,a class of materials promising for antiferromagnetic *** expand this topic into a description of four key elements.(1)We start by describing THz spectroscopy of spin excitations for probing magnetic phase transitions in thermal *** acoustic magnons are useful indicators of spin reorientation transitions,electromagnons that arise from dynamic magnetoelectric couplings serve as a signature of inversion-symmetry-breaking phases at low temperatures.(2)We then review the strong laser driving scenario,where the system is excited far from equilibrium and thereby subject to modifications to the free-energy *** pathways for ultrafast laser manipulation of magnetic order are discussed.(3)Furthermore,we review a variety of protocols to manipulate coherent THz magnons in time and space,which are useful capabilities for antiferromagnetic spintronic applications.(4)Finally,new insights into the connection between dynamic magnetic coupling in condensed matter and the Dicke superradiant phase transition in quantum optics are *** presenting a review on an array of THz spin phenomena occurring in a single class of materials,we hope to trigger interdisciplinary efforts that actively seek connections between subfields of spintronics,which will facilitate the invention of new protocols of active spin control and quantum phase engineering.

关键词： terahertz spin dynamics magnetism orthoferrite ultrafast spectroscopy magneto-optics

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Modulation of ionic conduction using polarizable surfaces

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Physical Review Research 2023年第4期5卷 043174-043174页

作者： A. P. dos Santos F. Jiménez-Ángeles A. Ehlen M. Olvera de la Cruz Instituto de Física Universidade Federal do Rio Grande do Sul Caixa Postal 15051 CEP 91501-970 Porto Alegre RS Brazil Department of Materials Science and Engineering Northwestern University Evanston Illinois 60208 USA Applied Physics Program Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA

Hybrid ionic-electronic conductors have the potential to generate memory effects and neuronal behavior. The functionality of these mixed materials depends on ion motion through thin polarizable channels. Here, we explore different polarization models to show that the current and conductivity of electrolytes is higher when confined by conductors than by dielectrics. We find nonlinear currents in both dielectrics and conductors, and we recover the known linear (Ohmic) result only in the two-dimensional limit between conductors. We show that the polarization charge location impacts electrolyte structure and transport properties. This work suggests a mechanism to induce memristor hysteresis loops using conductor-dielectric switchable materials.

关键词： Electric polarization Electrical conductivity Resistive switching

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Electronic and Optical Excitations in van der Waals materials from a Non-Empirical Wannier-Localized Optimally-Tuned Screened Range-Separated Hybrid Functional

arXiv

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arXiv 2024年

作者： Camarasa-Gómez, María Gant, Stephen E. Ohad, Guy Neaton, Jeffrey B. Ramasubramaniam, Ashwin Kronik, Leeor Department of Molecular Chemistry and Materials Science Weizmann Institute of Science Rehovoth7610001 Israel Department of Physics University of California BerkeleyCA94720 United States Materials Sciences Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Kavli Energy NanoSciences Institute at Berkeley University of California BerkeleyCA94720 United States Department of Mechanical and Industrial Engineering University of Massachusetts Amherst AmherstMA01003 United States Materials Science and Engineering Graduate Program University of Massachusetts AmherstMA01003 United States

Accurate prediction of electronic and optical excitations in van der Waals (vdW) materials is a long-standing challenge for density functional theory. The recently proposed Wannier-localized optimally-tuned screened range-separated hybrid (WOT-SRSH) functional has proven successful in non-empirical determination of electronic band gaps and optical absorption spectra for various covalent and ionic crystals. However, for vdW materials the tuning of the material- and structure-dependent functional parameters has, until now, only been attained semi-empirically. Here, we present a non-empirical WOT-SRSH approach applicable to vdW materials, with the optimal functional parameters transferable between monolayer and bulk. We apply this methodology to prototypical vdW materials: black phosphrous, moldybdenum disulfide, and hexagonal boron nitride (in the latter case including zero-point renormalization). We show that the WOT-SRSH approach consistently achieves accuracy levels comparable to experiments and ab initio many-body perturbation theory (MBPT) calculations for band structures and optical absorption spectra, both on its own and as an optimal starting point for MBPT calculations. Copyright © 2024, The Authors. All rights reserved.

关键词： Energy gap

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High pressure synthesis and characterization of the pyrochlore Dy2Pt2O7:A new spin ice material

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Chinese physics B 2020年第4期29卷 116-120页

作者： Qi Cui Yun-Qi Cai Xiang Li Zhi-Ling Dun Pei-Jie Sun Jian-Shi Zhou Hai-Dong Zhou Jin-Guang Cheng Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Materials Science and Engineering Program Mechanical EngineeringUniversity of Texas at AustinAustinTexas 78712USA Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement of Ministry of Education School of PhysicsBeijing Institute of TechnologyBeijing 100081China Department of Physics and Astronomy University of TennesseeKnoxvilleTN 37996USA School of Physics Georgia Institute of TechnologyAtlantaGA 30332USA Songshan Lake Materials Laboratory Dongguan 523808China

The cubic pyrochlore Dy2Pt2O7 was synthesized under 4 GPa and 1000℃ and its magnetic and thermodynamic properties were characterized by DC and AC magnetic susceptibility and specific heat down to 0.1 *** found that Dy2Pt2O7 does not form long-range magnetic order,but displays characteristics of canonical spin ice such as Dy2Pt2O7,including(1)a large effective moment 9.64μB close to the theoretical value and a small positive Curie-Weiss temperatureθCW=+0.77 K signaling a dominant ferromagnetic interaction among the Ising spins;(2)a saturation moment ~4.5μB being half of the total moment due to the local<111>Ising anisotropy;(3)thermally activated spin relaxation behaviors in the low(~1 K)and high(~20 K)temperature regions with different energy barriers and characteristic relaxation time;and most importantly,(4)the presence of a residual entropy close to Pauling’s estimation for water ice.

关键词： Dy2Pt2O7 pyrochlore oxide spin ice high-pressure synthesis

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Computing grain boundary diagrams of thermodynamic and mechanical properties

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npj Computational materials 2021年第1期7卷 1442-1453页

作者： Chongze Hu Yanwen Li Zhiyang Yu Jian Luo Department of Nanoengineering University of California San DiegoLa JollaCA 92093USA Program of Materials Science and Engineering University of California San DiegoLa JollaCA 92093USA State Key Laboratory of Photocatalysis on Energy and Environment College of ChemistryFuzhou University350002 FuzhouFujianP.R.China Department of Physics Southern University of Science and TechnologyShenzhenGuangdong 518055P.R.China

Computing the grain boundary(GB)counterparts to bulk phase diagrams represents an emerging research *** a classical embrittlement model system Ga-doped Al alloy,this study demonstrates the feasibility of computing temperature-and composition-dependent GB diagrams to represent not only equilibrium thermodynamic and structural characters,but also mechanical ***,hybrid Monte Carlo and molecular dynamics(MC/MD)simulations are used to obtain the equilibrium GB structure as a function of temperature and *** GB structures are validated by aberrationcorrected scanning transmission electron ***,MD tensile tests are performed on the simulated equilibrium GB *** diagrams are computed for not only GB adsorption and structural disorder,but also interfacial structural and chemical widths,MD ultimate tensile strength,and MD tensile *** study suggests a research direction to investigate GB composition–structure–property relationships via computing GB diagrams of thermodynamic,structural,and mechanical(or potentially other)properties.

关键词： grain toughness alloy

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Persistent Room-Temperature Photodarkening in Cu-Doped β−Ga2O3

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Physical Review Letters 2022年第7期128卷 077402-077402页

作者： J. Jesenovec C. Pansegrau M. D. McCluskey J. S. McCloy T. D. Gustafson L. E. Halliburton J. B. Varley Institute of Materials Research Washington State University Pullman Washington 99164-2711 USA Materials Science and Engineering Program Washington State University Pullman Washington 99164 USA Department of Physics and Astronomy Washington State University Pullman Washington 99164-2814 USA Department of Engineering Physics Air Force Institute of Technology Wright-Patterson Air Force Base Dayton Ohio 45433 USA Department of Physics and Astronomy West Virginia University Morgantown West Virginia 26506-6315 USA Lawrence Livermore National Laboratory Livermore California 94551-0808 USA

β−Ga2O3 is an ultrawide band gap semiconductor with emerging applications in power electronics. The introduction of acceptor dopants yields semi-insulating substrates necessary for thin-film devices. In the present work, exposure of Cu-doped β−Ga2O3 to UV light >4 eV is shown to cause large, persistent photo-induced darkening at room temperature. Electron paramagnetic resonance spectroscopy indicates that light exposure converts Cu2+ to Cu3+, a rare oxidation state that is responsible for the optical absorption. The photodarkening is accompanied by the appearance of O─H vibrational modes in the infrared spectrum. Hybrid function calculations show that Cu acceptors can favorably complex with hydrogen donors incorporated as interstitial (Hi) or substitutional (HO) defects. When CuGa−HO complexes absorb light, hydrogen is released, contributing to the observed Cu3+ species and O─H modes.

关键词： Doped semiconductors Semiconductor compounds Wide band gap systems Electron paramagnetic resonance Fourier transform infrared spectroscopy Optical absorption spectroscopy

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Defect engineering Centrosymmetric 2D Material Flexocatalysts

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Small 2024年第31期20卷 e2401116页

作者： Chen, Yu-Ching Chen, Po-Han Liao, Yin-Song Chou, Jyh-Pin Wu, Jyh Ming Department of Materials Science and Engineering National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Ph.D. Program in Prospective Functional Materials Industry National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Tsing Hua Interdisciplinary Program National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Department of Physics National Changhua University of Education No. 1 Jin-De Road Changhua500 Taiwan High Entropy Materials Center National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan

In this study, the flexoelectric characteristics of 2D TiO2 nanosheets are examined. The theoretical calculations and experimental results reveal an excellent strain-induced flexoelectric potential (flexopotential) by an effective defect engineering strategy, which suppresses the recombination of electron–hole pairs, thus substantially improving the catalytic activity of the TiO2 nanosheets in the degradation of Rhodamine B dye and the hydrogen evolution reaction in a dark environment. The results indicate that strain-induced bandgap reduction enhances the catalytic activity of the TiO2 nanosheets. In addition, the TiO2 nanosheets degraded Rhodamine B, with kobs being ≈1.5 × 10−2 min−1 in dark, while TiO2 nanoparticles show only an adsorption effect. 2D TiO2 nanosheets achieve a hydrogen production rate of 137.9 µmol g−1 h−1 under a dark environment, 197% higher than those of TiO2 nanoparticles (70.1 µmol g−1 h−1). The flexopotential of the TiO2 nanosheets is enhanced by increasing the bending moment, with excellent flexopotential along the y-axis. Density functional theory is used to identify the stress-induced bandgap reduction and oxygen vacancy formation, which results in the self-dissociation of H2O on the surface of the TiO in the dark. The present findings provide novel insights into the role of TiO2 flexocatalysis in electrochemical reactions. © 2024 Wiley-VCH GmbH.

关键词： Titanium dioxide

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Folding Graphene into Super-Strong, Z-Laminated Membranes

SSRN

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SSRN 2023年

作者： Santos, Ian Daniell Hofmann, Mario Tjarks, Patrick Muthu, Jeyavelan Lin, You-Chen Yen, Zhi-Long Chand, Pradyumna Kumar Raman, Radha Rouhani, Mehdi Jeng, Yeau-Ren Nguyen, Dinh-Tuan Hsieh, Ya-Ping Department of Physics National Taiwan University Taipei106 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica National Taiwan University Taiwan Institute of Physics Academia Sinica Taipei106 Taiwan Institute for Atomic and Molecular Sciences Academia Sinica Taipei106 Taiwan Department of Chemistry National Taiwan University Taipei106 Taiwan Department of Physics National Central University Taoyuan320 Taiwan Molecular Science and Technology Program Taiwan International Graduate Program Academia Sinica National Central University Taiwan Department of Materials Science and Engineering National Cheng Kung University Tainan70101 Taiwan

We here demonstrate the strengthening of graphene, an atomically thin carbon allotrope, by out-of-plane folding. Through lateral confinement of graphene at the water-air interface, buckling was induced in suspended flakes leading to an unexpected folding transition beyond a critical surface pressure. The emergence of folding was confirmed by in-situ reflectivity and ex-situ microscopy and imparts graphene assemblies with a unique "z-laminated" morphology. Molecular dynamics simulations indicate an enhanced adhesion between neighboring flakes compared to lateral sliding which was confirmed by a surface pressure hysteresis during the folding process. Mechanical testing reveals superior Young’s modulus and Yield strength when compared to conventional graphene assemblies and even compared to composites. We demonstrate the potential of folding for graphene-based structural materials, tribological layers, and functional electrochemical coatings. Finally, the complete recyclability of z-laminated graphene opens up new routes towards sustainable nanostructured materials. © 2023, The Authors. All rights reserved.

关键词： Graphene

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