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Negative terahertz conductivity at vertical carrier injection in a black-Arsenic-Phosphorus-Graphene heterostructure integrated with a light-emitting diode

arXiv

引用

arXiv 2019年

作者： Ryzhii, Victor Ryzhii, Maxim Otsuji, Taiichi Karasik, Valery E. Leiman, Vladimir G. Mitin, Vladimir Shur, Michael S. Research Institute of Electrical Communication Tohoku University Sendai980-8577 Japan Institute of Ultra High Frequency Semiconductor Electronics of RAS Moscow117105 Russia Center for Photonics and Infrared Technology Bauman Moscow State Technical University Moscow111005 Russia Center for Photonics and Two-Dimensional Materials Moscow Institute of Physics Technology Dolgoprudny141700 Russia Department of Computer Science and Engineering University of Aizu Aizu-Wakamatsu965-8580 Japan Department of Electrical Engineering University at Buffalo SUNY BuffaloNY1460-1920 United States Department of Electrical Computer and Systems Engineering Rensselaer Polytechnic Institute TroyNY12180 United States

We propose and analyze the heterostructure comprising a black-arsenic-phosphorus layer (bAs1−xPxL) and a graphene layer (GL) integrated with a light-emitting diode (LED). The integrated b-As1−xPxL-GL-LED heterostructure can serve as an active part of the terahertz (THz) laser using the interband radiative transitions in the GL. The feasibility of the proposed concept is enabled by the combination of relatively narrow energy gap in the b-As1−xPxL and the proper band alignment with the GL. The operation of the device in question is associated with the generation of the electron-hole pairs by the LED emitted near-infrared radiation in the b-As1−xPxL, cooling of the photogenerated electrons and holes in this layer, and their injection into the GL. Since the minimum b-As1−xPL energy gap (∆G 0.15 eV) is smaller than the energy of optical phonons in the GL, (~ω0 0.2 eV), the injection into the GL can lead to a relatively weak heating of the two-dimensional electron-hole plasma (2D-EHP) in the GL. At the temperatures somewhat lower than the room temperature, the injection can cool the 2D-EHP. This is beneficial for the interband population inversion in the GL, reinforcement of its negative dynamic conductivity, and the realization of the optical and plasmonic modes lasing supporting the new types of the THz radiation sources. Copyright © 2019, The Authors. All rights reserved.

关键词： Light emitting diodes

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3D Microstructures: Transparent, Compliant 3D Mesostructures for Precise Evaluation of Mechanical Characteristics of Organoids (Adv. Mater. 25/2021)

引用

Advanced materials 2021年第25期33卷

作者： Hanjun Ryu Yoonseok Park Haiwen Luan Gokhan Dalgin Kira Jeffris Hong-Joon Yoon Ted S. Chung Jong Uk Kim Sung Soo Kwak Geumbee Lee Hyoyoung Jeong Jihye Kim Wubin Bai Joohee Kim Yei Hwan Jung Andrew K. Tryba Joseph W. Song Yonggang Huang Louis H. Philipson John D. Finan John A. Rogers Querrey Simpson Institute for Bioelectronics Northwestern University Evanston IL 60208 USA School of Advanced Materials Science and Engineering Sungkyunkwan University (SKKU) Suwon 16419 Republic of Korea Section of Adult and Pediatric Endocrinology Diabetes and Metabolism Kovler Diabetes Center The University of Chicago Chicago IL 60637 USA Department of Mechanical and Industrial Engineering University of Illinois at Chicago Chicago IL 60607 USA Department of Biomedical Engineering Northwestern University Evanston IL 60208 USA School of Chemical Engineering Sungkyunkwan University (SKKU) Suwon 16419 Republic of Korea Department of Applied Physical Sciences University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA Department of Electronic Engineering Hanyang University Seoul 04763 Republic of Korea Section of Pediatric Neurology Department of Pediatrics The University of Chicago Chicago IL 60637 USA Center for Bio-Integrated Electronics Northwestern University Evanston IL 60208 USA Department of Mechanical Engineering Northwestern University Evanston IL 60208 USA Department of Civil and Environmental Engineering Northwestern University Evanston IL 60208 USA Department of Materials Science and Engineering Northwestern University Evanston IL 60208 USA Department of Medicine and Kovler Diabetes Center The University of Chicago Chicago IL 60637 USA Department of Chemistry Northwestern University Evanston IL 60208 USA Department of Electrical and Computer Engineering Northwestern University Evanston IL 60208 USA Departments of Neurological Surgery Feinberg School of Medicine Northwestern University Chicago IL 60611 USA

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Optomechanically Induced Birefringence and Faraday Effect

arXiv

引用

arXiv 2019年

作者： Duggan, Robert del Pino, Javier Verhagen, Ewold Alù, Andrea Department of Electrical and Computer Engineering University of Texas at Austin AustinTX78712 United States Center for Nanophotonics AMOLF Science Park 104 Amsterdam1098 XG Netherlands Photonics Initiative Advanced Science Research Center City University of New York NY10031 United States Physics Program Graduate Center City University of New York NY10016 United States Department of Electrical Engineering City College of The City University of New York NY10031 United States

We demonstrate an optomechanical platform where optical mode conversion mediated by mechanical motion enables arbitrary tailoring of polarization states of propagating light fields. Optomechanical interactions are realized in a Fabry-Perót resonator, which naturally supports two polarization-degenerate states while an optical control field induces rotational symmetry breaking. Applying such principles, the entire Poincaré sphere is spanned by just optical control of the driving field, realizing reciprocal and non-reciprocal optomechanically-induced birefringence for linearly polarized and circularly polarized control driving. A straightforward extension of this setup also enables all-optical tunable isolation and circulation. Our findings open new avenues to exploit optomechanics for arbitrary manipulation of light polarization. Copyright © 2019, The Authors. All rights reserved.

关键词： Birefringence

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Identification of a functional point defect in SrTiO3

引用

Physical Review materials 2018年第6期2卷 060403(R)-060403(R)页

作者： Daesu Lee Hongwei Wang Brenton A. Noesges Thaddeus J. Asel Jinbo Pan Jung-Woo Lee Qimin Yan Leonard J. Brillson Xifan Wu Chang-Beom Eom Department of Materials Science and Engineering University of Wisconsin–Madison Madison Wisconsin 53706 USA Department of Physics Temple University Philadelphia Pennsylvania 19122 USA Department of Electrical and Computer Engineering and Department of Physics The Ohio State University Columbus Ohio 43210 USA

Unveiling both the presence and nature of point defects is one of the biggest challenges in condensed matter physics and materials science. Particularly in complex oxides, even a minute amount of unavoidable point defects could generate novel physical phenomena and functions, such as visible light emission and ferroelectricity, yet it remains elusive to clearly identify such point defects. Here, taking SrTiO3 as a model system, we show that iterative feedback among atomic-layer- and stoichiometry-controlled thin-film epitaxy, hybrid density functional theory, and high-resolution cathodoluminescence spectroscopy allows for the identification of a functional cationic defect, the Ti antisite (TiSr) defect. Our cathodoluminescence measurements reveal sub-band-gap luminescence, whose spectral fine structures show excellent quantitative agreement, as well as a one-to-one correspondence, with the theoretically predicted optical transitions from intrinsic point defects such as TiSr. Guided by the theory and spectroscopic results, we also control a cation stoichiometry, and it in turn results in good systematics in cathodoluminescence spectra. Not limited to the identification of TiSr, this approach allows for more reliable, self-consistent defect study, and provides critical insight into a microscopic picture of point defects in complex oxides.

关键词： Defects

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Generation and Hall effect of skyrmions enabled via using nonmagnetic point contacts

arXiv

引用

arXiv 2019年

作者： Wang, Zidong Zhang, Xichao Xia, Jing Zhao, Le Wu, Keyu Yu, Guoqiang Wang, Kang L. Liu, Xiaoxi Te Velthuis, Suzanne G. E. Hoffmann, Axel Zhou, Yan Jiang, Wanjun State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China School of Science and Engineering Chinese University of Hong Kong Shenzhen Guangdong518172 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China Department of Electrical Engineering University of California Los AngelesCA90095 United States Department of Electrical and Computer Engineering Shinshu University 4-17-1 Wakasato Nagano380-8553 Japan Materials Science Division Argonne National Laboratory LemontIL60439 United States

To enable functional skyrmion-based spintronic devices, the controllable generation and manipulation of skyrmions is essential. While the generation of skyrmions by using a magnetic geometrical constriction has already been demonstrated, this approach is difficult to combine with a subsequent controlled manipulation of skyrmions. The high efficiency of skyrmion generation from magnetic constrictions limits the useful current density, resulting in stochastic skyrmion motion, which may obscure topological phenomena such as the skyrmion Hall effect. In order to address this issue, we designed a nonmagnetic conducting Ti/Au point contact in devices made of Ta/CoFeB/TaOx trilayer films. By applying high voltage pulses, we experimentally demonstrated that skyrmions can be dynamically generated. Moreover, the accompanied spin topology dependent skyrmion dynamics-the skyrmion Hall effect is also experimentally observed in the same devices. The creation process has been numerically reproduced through micromagnetic simulations in which the important role of skyrmion-antiskyrmion pair generation is identified. The motion and Hall effect of the skyrmions, immediately after their creation is described using a modified Thiele equation after taking into account the contribution from spatially inhomogeneous spin-orbit torques and the Magnus force. The simultaneous generation and manipulation of skyrmions using a nonmagnetic point contact could provide a useful pathway for designing novel skyrmion based devices. Copyright © 2019, The Authors. All rights reserved.

关键词： Topology

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Dynamic Defrosting on Superhydrophobic and Biphilic Surfaces

SSRN

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SSRN 2019年

作者： Chavan, Shreyas Gurumukhi, Yashraj Sett, Soumyadip Boyina, Kalyan Ramesh, Srivasupradha Sokalski, Peter Fortelka, Kirk Lira, Maury Park, Deokgeun Chen, Juo-Yun Hegde, Shreyas Miljkovic, Nenad Department of Mechanical Science and Engineering University of Illinois Urbana61801 United States Frederick Seitz Materials Research Laboratory University of Illinois at Urbana–Champaign UrbanaIL61801 United States Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign UrbanaIL61801 United States Kyushu University 744 Moto-oka Nishi-ku Fukuoka819-0395 Japan

Ice formation and accretion present serious concerns for many building energy applications. In the heating, ventilation, air-conditioning, and refrigeration sectors, the most common approach to remove frost from a surface (defrost) is to reverse the system cycle direction and heat the working fluid. However, water retention on the heat exchanger during defrosting decreases the long term heat transfer performance. Here, we study the defrosting behavior of superhydrophobic and biphilic surfaces comprising of spatially distinct superhydrophobic (θa → 180°) and hydrophilic (θa = 78°) domains. Using top and side view optical imaging, we show that superhydrophobic regions undergo dynamic defrosting, where the frozen ice/frost layer undergoes spontaneous motion via the formation of a highly mobile slush. We experimentally show that the high mobility of dynamic defrosting enables the use of surface forces to ‘pull’ and remove the slush from the surface prior to it completely melting, even in the absence of forces such as gravity or shear. To explore the effect of pattern heterogeneity, we studied various biphilic patterns inspired from nature such as the banana leaf. We optimized the design space with respect to minimizing water retention during defrosting. Our work not only provides the fundamental understanding required for the design of heterogeneous defrosting coatings, but also elucidates the role of wettability gradients on defrosting dynamics for a plethora of energy applications. © 2019, The Authors. All rights reserved.

关键词： Hydrophilicity

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Spin Absorption by In Situ Deposited Nanoscale Magnets on Graphene Spin Valves

引用

Physical Review Applied 2018年第4期10卷 044050-044050页

作者： Walid Amamou Gordon Stecklein Steven J. Koester Paul A. Crowell Roland K. Kawakami Program of Materials Science and Engineering University of California Riverside California 92521 USA School of Physics and Astronomy University of Minnesota Minneapolis Minnesota 55455 USA Department of Electrical and Computer Engineering University of Minnesota Minneapolis Minnesota 55455 USA Department of Physics The Ohio State University Columbus Ohio 43210 USA

An in situ measurement of spin transport in a graphene nonlocal spin valve is used to quantify the spin current absorbed by a small (250×750nm2) metallic island. The experiment allows for successive depositions of either Fe or Cu without breaking vacuum, so that the thickness of the island is the only parameter that is varied. Furthermore, by measuring the effect of the island using separate contacts for injection and detection, we isolate the effect of spin absorption from any change in the spin injection and detection mechanisms. As inferred from the thickness dependence, the effective spin current je=(2e/ℏ)js absorbed by Fe is as large as 108A/m2. The maximum value of je is limited by the resistance-area product of the graphene/Fe interface, which is as small as 3Ωμm2. The spin current absorbed by the same thickness of Cu is smaller than that for Fe, as expected given the longer spin-diffusion length and larger spin resistance of Cu compared to Fe. These results allow for a quantitative assessment of the prospects for achieving spin-transfer-torque switching of a nanomagnet using a graphene-based nonlocal spin valve.

关键词： Island Spin current Spin transfer torque Spintronics Ferromagnets Graphene Magnetic nanoparticles Spin valves

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A Novel modeling approach for all-dielectric metasurfaces using deep neural networks

arXiv

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arXiv 2019年

作者： An, Sensong Fowler, Clayton Zheng, Bowen Shalaginov, Mikhail Y. Tang, Hong Li, Hang Zhou, Li Ding, Jun Agarwal, Anuradha Murthy Rivero-Baleine, Clara Richardson, Kathleen A. Gu, Tian Hu, Juejun Zhang, Hualiang Department of Electrical & Computer Engineering University of Massachusetts Lowell LowellMA United States Department of Materials Science & Engineering Massachusetts Institute of Technology CambridgeMA United States Shanghai Key Laboratory of Multidimensional Information Processing East China Normal University Shanghai China Lockheed Martin Corporation OrlandoFL United States CREOL University of Central Florida OrlandoFL United States

Metasurfaces have become a promising means for manipulating optical wavefronts in flat and high-performance optical devices. Conventional metasurface device design relies on trial-and-error methods to obtain target electromagnetic (EM) response, an approach that demands significant efforts to investigate the enormous number of possible meta-atom structures. In this paper, a deep neural network approach is introduced that significantly improves on both speed and accuracy compared to techniques currently used to assemble metasurface-based devices. Our neural network approach overcomes three key challenges that have limited previous neural-network-based design schemes: input/output vector dimensional mismatch, accurate EM-wave phase prediction, as well as adaptation to 3-D dielectric structures, and can be generically applied to a wide variety of metasurface device designs across the entire electromagnetic spectrum. Using this new methodology, examples of neural networks capable of producing on-demand designs for meta-atoms, metasurface filters, and phase-change reconfigurable metasurfaces are demonstrated. Copyright © 2019, The Authors. All rights reserved.

关键词： Deep neural networks

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Corrigendum to “X-ray photoelectron spectroscopy investigation of the valence band offset at beryllium oxide-diamond interfaces” [Diam. Relat. Mater. 101 (2020) 107647–7]

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Diamond and Related materials 2021年 111卷

作者： Donghyi Koh Todd W. Hudnall Christopher W. Bielawski Sanjay K. Banerjee Justin Brockman Markus Kuhn Sean W. King Microelectronics Research Center Department of Electrical and Computer Engineering University of Texas at Austin 10100 Burnet Road Austin TX 78758 United States of America Department of Chemistry and Biochemistry Texas State University San Marcos TX 78666 United States of America Center for Multidimensional Carbon Materials (CMCM) Institute for Basic Science (IBS) Ulsan 44919 Republic of Korea Department of Chemistry Ulsan National Institute of Science and Technology (UNIST) Ulsan 44919 Republic of Korea Department of Energy Engineering Ulsan National Institute of Science and Technology (UNIST) Ulsan 44919 Republic of Korea Logic Technology Development Intel Corporation Hillsboro OR 97124 United States of America

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Polar Polarization Mode and Average Radical Flux Intensity Measurements Based on All Optical Spatial Communication Systems

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Journal of Optical Communications 2019年第s1期45卷 s53-s61页

作者： Amiri, I.S. Rashed, Ahmed Nabih Zaki Jahan, Sohely Paul, Bikash Kumar Ahmed, Kawsar Computational Optics Research Group Advanced Institute of Materials Science Ton Duc Thang University Ho Chi Minh City700000 Viet Nam Faculty of Applied Sciences Ton Duc Thang University Ho Chi Minh City Viet Nam Faculty of Electronic Engineering Electronics and Electrical Communications Engineering Department Menoufia University Menouf Menoufia32951 Egypt Department of Computer Science and Engineering University of Barisal Kornokathi Barisal8200 Bangladesh Ashulia Savar1342 Bangladesh Department of Information and Communication Technology Mawlana Bhashani Science and Technology University Santosh Tangail1902 Bangladesh Group of Bio-photomatiχ Mawlana Bhashani Science and Technology University Santosh Tangail1902 Bangladesh

This study presents the polar polarization mode and average radical intensity flux distribution measurements based on all optical spatial communication systems. The numerical technique that is applied with the simulation model is the diffraction fast Fourier integral transform. Spatial optical sources are used such as continuous wave (CW) laser and vertical cavity surface-emitting laser (VCSEL) with spatial connector and spatial aperture. Spatial temporal polarization effects are taken into account. Percentage encircled flux/average flux radical intensity and polar radical polarization are measured with spatial connector distance and spatial aperture width. The encircled flux is constant at 95% of its value in the case of VCSEL laser source at a radical distance of exactly 10 μm. However, the encircled flux is constant at 92 %of its value in the case of CW laser source at a radical distance of exactly 6 μm. It is noticed that the encircled flux increases with increasing radial distance of spatial apertures that are used with two suggested light sources. The encircled flux is constant at 93 % of its value in the case of VCSEL laser source at a radical distance of exactly 10 μm. © 2019 Walter de Gruyter GmbH, Berlin/Boston.

关键词： Surface emitting lasers

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