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arXiv 2021年

作者： Prado, Marcus Sgrignuoli, Fabrizio Chen, Yuyao Dal Negro, Luca Pinheiro, Felipe A. Instituto de Física Universidade Federal do Rio de Janeiro Rio de Janeiro-RJ21941-972 Brazil Department of Electrical and Computer Engineering Boston University 8 Saint Mary's Street BostonMA02215 United States Division of Material Science and Engineering Boston University 15 Saint Mary's Street BrooklineMA02446 United States Department of Physics Boston University 590 Commonwealth Avenue BostonMA02215 United States

We investigate the spatial decay and temporal localization properties of quasimodes (i.e., scattering resonances) of two-dimensional Vogel spirals, composed of deterministic, aperiodic arrays of electric dipoles. By determining the structural entropy and localization maps of Vogel spirals using the Green’s matrix method, we show that three distinctive decay types of quasimodes coexist in Vogel spirals: exponential, power-law, and Gaussian. While the exponential and the power-law decays typically occur in disordered media and multifractal systems, respectively, the Gaussian decay is demonstrated to characterize, on average, the most localized quasimodes of Vogel spirals, both spatially (smallest participation ratios) and temporarily (longest lifetimes). These decay forms are demonstrated by a no-fitting analysis of the localization maps, independently corroborated by calculating the electric field in real space, which also provides a direct evidence of the algebraic spatial decay of critical quasimodes. Altogether our findings unveil a rich spectrum of both long-lived and spatially localized quasimodes that coexist in Vogel spirals and can be of direct relevance to novel optical functionalities for applications to light sources and sensing devices. Copyright © 2021, The Authors. All rights reserved.

关键词： Light sources

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Front Cover: General Doping Chemistry of Carbon materials (ChemNanoMat 4/2023)

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ChemNanoMat 2023年第4期9卷

作者： Dr. Mohammad Boshir Ahmed Jahangir Alom Md. Saif Hasan Md. Asaduzzaman Md. Saifur Rahman Raqibul Hossen Dr. Mohammad Abu Hasan Johir Prof. Dr. Mohammad Taufiq Alam Prof. Dr. John L. Zhou Prof. Dr. Yanqiu Zhu Dr. Masoumeh Zargar School of Material Science and Engineering Gwangju Institute of Science and Technology 61005 Gwangju Republic of Korea Department of Applied Chemistry and Chemical Engineering University of Rajshahi 6205 Rajshahi Bangladesh Department of Biomedical Engineering Texas A&M University College Station TX 77843 United States School of Electrical Engineering and Computer Science Gwangju Institute of Science and Technology 61005 Gwangju Republic of Korea Center for Green Technology School of Civil and Environmental Engineering University of Technology Sydney 15 Broadway 2007 Sydney NSW Australia College of Engineering Mathematics and Physical Sciences University of Exeter Exceter city EX4 4QF United Kingdom School of Engineering Edith Cowan University 6027 Joondalup WA Australia

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Observation of Photoinduced Terahertz Gain in GaAs Quantum Wells: Evidence for Radiative Two-Exciton-to-Biexciton Scattering

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Physical Review Letters 2020年第16期125卷 167401-167401页

作者： Xinwei Li Katsumasa Yoshioka Qi Zhang Nicolas Marquez Peraca Fumiya Katsutani Weilu Gao G. Timothy Noe, II John D. Watson Michael J. Manfra Ikufumi Katayama Jun Takeda Junichiro Kono Department of Electrical and Computer Engineering Rice University Houston Texas 77005 USA Department of Physics Graduate School of Engineering Science Yokohama National University Yokohama 240-8501 Japan School of Physics Nanjing University Nanjing 210093 China Department of Physics and Astronomy Rice University Houston Texas 77005 USA Department of Physics and Astronomy Purdue University West Lafayette Indiana 47907 USA Department of Material Science and NanoEngineering Rice University Houston Texas 77005 USA

We have observed photoinduced negative optical conductivity, or gain, in the terahertz frequency range in a GaAs multiple-quantum-well structure in a strong perpendicular magnetic field at low temperatures. The gain is narrow band: it appears as a sharp peak (linewidth <0.45 meV) whose frequency shifts with applied magnetic field. The gain has a circular-polarization selection rule: a strong line is observed for hole-cyclotron-resonance-active polarization. Furthermore, the gain appears only when the exciton 1s state is populated, which rules out intraexcitonic transitions to be its origin. Based on these observations, we propose a possible process in which the stimulated emission of a terahertz photon occurs while two free excitons scatter into one biexciton in an energy and angular-momentum conserving manner.

关键词： Biexcitons Excitons Optical conductivity Photoinduced effect III-V semiconductors Quantum wells Photoluminescence Terahertz spectroscopy

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Magnetic and Magnetocaloric Properties of Fe 2AIB 2 Synthesized by Single-Step Reactive Hot Pressing

SSRN

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SSRN 2020年

作者： Bennett, Steven P. Kota, Sankalp ElBidweihy, Hatem Hanner, Luke A. Finkel, Peter Barsoum, Michel W. Parker, Joseph F. Materials Science and Technology Division U.S. Naval Research Laboratory WashingtonDC20375 United States Department of Materials Science and Technology Division & Engineering Drexel University PhiladelphiaPA44720 United States Department of Electrical and Computer Engineering U.S. Naval Academy AnnapolisMD21402 United States Material Science and Technology Division

A single-step reactive hot-pressing technique was used to synthesize dense, polycrystalline samples of the nanolaminated MAB phase, Fe2AlB2. The process yielded nearly single-phase stoichiometric Fe2AlB2 materials containing only Al2O3 as the impurity phase in a fraction of the synthesis time typically required for the more commonly used arc-melting methods. To determine crystalline, magnetic, and stoichiometric properties, samples were analyzed by X-ray diffraction, energy dispersive x-ray spectroscopy, X-ray photoelectron spectroscopy, and temperature-dependent vibrating sample magnetometry. The results of both techniques show magnetic and magnetocaloric properties similar to those obtained in literature by other methods such as multi-day arc melting and annealing. © 2020, The Authors. All rights reserved.

关键词： Magnetism

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Sub-nanosecond Infrared Photodetection using III-V Colloidal Quantum Dots

Research Square

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Research Square 2020年

作者： Sun, Bin Najarian, Amin Morteza Zheng, Chao Sagar, Laxmi Kishore Choi, Min-Jae Li, Xiyan Levina, Larissa Baek, Se-Woong Lee, Seungjin Kirmani, Ahmad R. Abed, Jehad Liu, Mengxia Li, Peicheng Richter, Lee J. Voznyy, Oleksandr Lu, Zheng Hong de Arquer, F. Pelayo García Sargent, Edward H. Department of Electrical and Computer Engineering University of Toronto 35 St George Street TorontoONM5S 1A4 Canada Department of Electrical and Computer Engineering University of Toronto TorontoONM5S 1A4 Canada GaithersburgMD20899 United States Department of Material Science and Engineering University of Toronto 184 College St TorontoONM5S 3E4 Canada

Colloidal quantum dots (CQDs) are promising materials for IR light detection due to their tunable bandgap and solution processing;but to date, the time response of CQD IR photodiodes has been inferior to that provided by Si and InGaAs. We reasoned that the high permittivity of II-VI CQDs leads to slow charge extraction due to screening and capacitance;whereas III-Vs – if their surface chemistry could be mastered – offer a strong covalent character for low permittivity and fast operation. In initial studies, we found that existing covalent character led to imbalanced charge transport in InAs, the result of unpassivated surfaces and uncontrolled heavy doping. We report surface management using amphoteric ligand coordination and find that it addresses simultaneously the In and As surface dangling bonds. The new InAs CQD solids combine high mobility (0.04 cm2 V-1 s-1) with a 4x reduction in permittivity compared to PbS CQDs. The resulting photodiodes achieve a response time faster than 300 ps – a more than 100x improvement compared to the best previously-reported CQD photodiodes – combined with an external quantum efficiency (EQE) of 30% at 940 nm. © 2020, CC BY.

关键词： Semiconductor quantum dots

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Observation of the out-of-plane polarized spin current from CVD grown WTe2

arXiv

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arXiv 2021年

作者： Shi, Shuyuan Li, Jie Hsu, Chuang-Han Lee, Kyusup Wang, Yi Yang, Li Wang, Junyong Wang, Qisheng Wu, Hao Zhang, Wenfeng Eda, Goki Liang, Gengchiau Chang, Haixin Yang, Hyunsoo Department of Electrical and Computer Engineering National University of Singapore 117576 Singapore Quantum-Nano Matter and Device Lab State Key Laboratory of Material Processing and Die & Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan430074 China Institute of Physics Academia Sinica Taipei11529 Taiwan Key Laboratory of Materials Modification by Laser Ion and Electron Beams Ministry of Education Dalian University of Technology Dalian116024 China Centre for Advanced 2D Materials National University of Singapore 6 Science Drive 2 117546 Singapore Department of Physics National University of Singapore 117542 Singapore

Weyl semimetal Td-phase WTe2 possesses the spin-resolved band structure with strong spin-orbit coupling, holding promises as a useful spin source material. The noncentrosymmetric crystalline structure of Td-WTe2 endows the generation of the out-of-plane polarized spin, which is of great interest in magnetic memory applications. Previously, WTe2 was explored in spin devices based on mechanically exfoliated single crystal flakes with a size of micrometers. For practical spintronics applications, it is highly desirable to implement wafer-scale thin films. In this work, we utilize centimeter-scale chemical vapor deposition (CVD)-grown Td-WTe2 thin films and study the spin current generation by the spin torque ferromagnetic resonance technique. We find the in-plane and out-of-plane spin conductivities of 7.36 × 103 (ħ/2e) (Ωm)–1 and 1.76 × 103 (ħ/2e) (Ωm)–1, respectively, in CVD-growth 5 nm-WTe2. We further demonstrate the current induced magnetization switching in WTe2/NiFe at room temperature in the domain wall motion regime, which may invigorate potential spintronic device innovations based on Weyl semimetals. Copyright © 2021, The Authors. All rights reserved.

关键词： Thin films

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Erratum: “Growth of β-Ga2O3 and ε/κ-Ga2O3 on AlN(0001) by molecular-beam epitaxy” [APL Mater. 11, 111113 (2023)]

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APL materials 2024年第1期12卷

作者： Sushma Raghuvansy Jon P. McCandless Marco Schowalter Alexander Karg Manuel Alonso-Orts Martin S. Williams Christian Tessarek Stephan Figge Kazuki Nomoto Huili Grace Xing Darrell G. Schlom Andreas Rosenauer Debdeep Jena Martin Eickhoff Patrick Vogt Institute of Solid-State Physics University of Bremen Otto-Hahn-Allee 1 28359 Bremen Germany School of Electrical and Computer Engineering Cornell University Ithaca New York 14853 USA MAPEX Center for Materials and Processes University of Bremen 28359 Bremen Germany Department of Material Science and Engineering Cornell University Ithaca New York 14853 USA Kavli Institute at Cornell for Nanoscale Science Cornell University Ithaca New York 14853 USA Leibniz-Institut fur Kristallzüchtung Max-Born-Str. 2 12489 Berlin Germany

It was brought to our attention that Fig. 1 in the published version of our paper1 is incorrect and does not represent the growth rate diagrams (Γ-diagrams) of

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Remote epitaxy and freestanding wide bandgap semiconductor membrane technology

Nature Reviews Electrical Engineering

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Nature Reviews electrical engineering 2024年 680-689页

作者： Minseong Park Yongmin Baek Kyusang Lee Takuji Maekawa Kyungwook Hwang Youngtek Oh Jim Cable Watanabe Noriyuki Kisik Choi Young-Kyun Noh Department of Electrical and Computer Engineering University of Virginia Charlottesville VA USA Future Semiconductor Business Charlottesville VA USA Department of Material Science and Engineering University of Virginia Charlottesville VA USA ROHM Research and Development Headquarters ROHM Co. Ltd Kyoto Japan Samsung Advanced Institute of Technology Suwon South Korea NTT Device Technology Laboratories NTT Corporation Atsugi Kanagawa Japan IBM Research Albany NY USA IVWorks Co. Ltd Daejeon South Korea

The emergence of artificial intelligence, big data processing, electrical vehicle technologies and so on necessitates a new approach to address the scaling, power efficiency and performance challenges of silicon (Si)-based technology beyond Moore’s law. As a complementary technology, wide bandgap semiconductors, including GaN and SiC, have attracted great attention owing to their unique features of high carrier mobility and high breakdown voltages. However, there are still limitations for widespread applications of wide bandgap semiconductors including scalability, high production cost and thermal management. To overcome these barriers, remote epitaxy and 2D layer transfer technology have been introduced and are in the process of being industrialized to produce single-crystalline semiconductor-based freestanding membranes. In this Perspective, we present the status and challenges for manufacturing GaN and SiC membranes based on remote epitaxy technology that offers significant advantages via wafer reuse and high-quality freestanding epilayer production. We also discuss how industrialization of advanced membrane technology can benefit numerous applications, including heterogeneously integrated circuits, power and radiofrequency systems.

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Wide-angle giant photonic spin Hall effect

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Physical Review B 2022年第7期106卷 075409-075409页

作者： Zhihao Chen Yu Chen Yaodong Wu Xinxing Zhou Handong Sun Tony Low Hongsheng Chen Xiao Lin Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Synergetic Innovation Center for Quantum Effects and Applications School of Physics and Electronics Hunan Normal University Changsha 410081 China International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology Engineering Technology Research Center for 2D Material Information Function Devices and Systems of Guangdong Province Institute of Microscale Optoelectronics Shenzhen University Shenzhen 518060 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore Centre for Disruptive Photonic Technologies (CDPT) School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore Department of Electrical and Computer Engineering University of Minnesota Minneapolis Minnesota 55455 USA Interdisciplinary Center for Quantum Information State Key Laboratory of Modern Optical Instrumentation ZJU-Hangzhou Global Scientific and Technological Innovation Center College of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China International Joint Innovation Center ZJU-UIUC Institute The Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China

The photonic spin Hall effect is a manifestation of the spin-orbit interaction of light and can be measured by a transverse shift δ of photons with opposite spins. The precise measurement of transverse shifts can enable many spin-related applications, such as precise metrology and optical sensing. However, this transverse shift is generally small (i.e., δ/λ<10−1, where λ is the wavelength), which impedes its precise measurement. To date, proposals to generate a giant spin Hall effect (namely, with δ/λ>102) have severe limitations, particularly its occurrence only over a narrow angular cone (with a width of Δθ<1∘). Here we propose a universal scheme to realize the wide-angle giant photonic spin Hall effect with Δθ>70∘ by exploiting the interface between free space and uniaxial epsilon-near-zero media. The underlying mechanism is ascribed to the almost-perfect polarization splitting between s and p polarized waves at the designed interface. Remarkably, this almost-perfect polarization splitting does not resort to the interference effect and is insensitive to the incident angle, which then gives rise to the wide-angle giant photonic spin Hall effect.

关键词： Light-matter interaction Photonics Spin Hall effect Spin-orbit coupling

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From hexagonal to rocksalt structure: A computational study of gallium selenide under hydrostatic pressure

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Physical Review B 2023年第20期108卷 205150-205150页

作者： Vo Khuong Dien Nguyen Thanh Tien Nguyen Duy Khanh Nguyen Thi Ngoc Han Ming-Fa Lin Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu 300 Taiwan College of Natural Sciences Can Tho University 3-2 Road Can Tho City 94000 Vietnam Laboratory for Computational Physics Institute for Computational Science and Artificial Intelligence Van Lang University Ho Chi Minh City 700000 Vietnam Faculty of Mechanical - Electrical and Computer Engineering School of Technology Van Lang University Ho Chi Minh City 700000 Vietnam Fschool Can Tho FPT University 600 Nguyen Van Cu Street Can Tho City 900000 Vietnam Department of Physics National Cheng Kung University 701 Tainan Taiwan Hierarchical Green-Energy Material (Hi-GEM) Research Center National Cheng Kung University 701 Tainan Taiwan

The understanding of pressure-dependent fundamental properties of materials is very essential, not only for basic scientific knowledge but also for advanced technological applications. Experimental observations have fully revealed the hexagonal-to-rocksalt phase transition in the GaSe system under high pressure. In this article we systematically investigate the pressure-induced structural phase transition and related phonon, electronic, and optical properties of hexagonal ɛ−GaSe through a complete first-principles theoretical framework developed by the density-functional-theory calculations. The study focuses on geometric optimization, electronic band structures, electron localization functions, phonon spectra, dielectric properties, and optical spectra of the GaSe system under hydrostatic pressure. This work also includes an analysis of the phase transformation mechanism using the solid-state nudged elastic band method. Our research sheds light on the physics of structural phase transitions in layered materials and offers potential for the development of pressure-manipulated electronics and optoelectronics.

关键词： Charge Chemical bonding Critical phenomena Dielectric properties electrical properties Excitons First-principles calculations Lattice dynamics Mechanical deformation Photonics Plasmonics Pressure effects Specific phase transitions Superconductors

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