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arXiv 2024年

作者： Pant, Nick Bushick, Kyle McAllister, Andrew Lee, Woncheol Van de Walle, Chris G. Kioupakis, Emmanouil Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Materials Science & Engineering University of Michigan Ann ArborMI48109 United States Department of Electrical Engineering & Computer Science University of Michigan Ann ArborMI48109 United States Materials Department University of California Santa BarbaraCA93106 United States

The quantum efficiency of AlGaN ultraviolet light-emitting diodes (LEDs) declines (droops) at increasing operating powers due to Auger-Meitner recombination (AMR). Using first-principles density-functional theory, we show that indirect AMR mediated by electron-phonon coupling and alloy disorder can induce bulk C coefficients as large as ∼10-31 cm6/s. Furthermore, we find that the confinement of carriers by polarization fields within quantum wells severely relaxes crystal-momentum conservation, which exacerbates the rate of AMR over radiative recombination by an order of magnitude relative to the bulk. This results in a striking decrease in quantum efficiency at high power. Suppressing polarization fields and jointly increasing the well width would greatly mitigate AMR and efficiency droop. Copyright © 2024, The Authors. All rights reserved.

关键词： Aluminum gallium nitride

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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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Optimisation-based sampling time selection for modelling the three interacting tanks

Optimisation-based sampling time selection for modelling the...

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International Conference on Advanced Mechatronics, Intelligent Manufacture, and Industrial Automation (ICAMIMIA)

作者： Helmy Rahadian Azka Muji Burohman Augie Widyotriatmo Endra Joelianto Engineering Physics Doctoral Program Institut Teknologi Bandung Bandung Indonesia Electrical Engineering Study Program Universitas Dian Nuswantoro Semarang Indonesia Research Center for Photonics National Research and Innovation Agency (BRIN) Tangerang Selatan Indonesia Instrumentation and Control Research Group Institut Teknologi Bandung Bandung Indonesia Institut Teknologi Bandung University Center of Excellence AI on Vision NLP & Big Data Analytics Bandung Indonesia

This paper considers parameters and sampling time identification of a three interacting tanks system. A novel tailor-made model is introduced to deal with the real plant in the laboratory. Experimental data are then exploited to perform parameter identification via particle swarm optimisation (PSO) method. In addition to the system parameters, we propose to simultaneously optimize the sampling selection in the optimisation process. Even though several well known sampling time selection are established, a more precise selection is required. It is shown in this paper that a meta-heuristic optimisation method (PSO) can be an efficient procedure for this problem. Moreover, three different error measures for performing optimisation are also discussed.

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Stationary Charge Radiation in Anisotropic Photonic Time Crystals

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Physical Review Letters 2023年第9期130卷 093803-093803页

作者： Huanan Li Shixiong Yin Huan He Jingjun Xu Andrea Alù Boris Shapiro MOE Key Laboratory of Weak-Light Nonlinear Photonics School of Physics Nankai University Tianjin 300071 China Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Department of Electrical Engineering City College of The City University of New York New York New York 10031 USA Physics Program Graduate Center City University of New York New York New York 10016 USA Department of Physics Technion-Israel Institute of Technology Haifa 32000 Israel

Time metamaterials offer a great potential for wave manipulation, drawing increasing attention in recent years. Here, we explore the exotic wave dynamics of an anisotropic photonic time crystal (APTC) formed by an anisotropic medium whose optical properties are uniformly and periodically changed in time. Based on a temporal transfer matrix formalism, we show that a stationary charge embedded in an APTC emits radiation, in contrast to the case of isotropic photonic time crystals, and its distribution in momentum space is controlled by the APTC band structure. Our approach extends the functionalities of time metamaterials, offering new opportunities for radiation generation and control, with implications for both classical and quantum applications.

关键词： Optical pumping Photonic crystals Photonics Time crystals

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Synthesis and Simulation Study of Titanium Dioxide-Based Nanomaterial for Electron Carrier Selective Contact Solar Cell

SSRN

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SSRN 2024年

作者： Yi, Junsin Rahman, Rafi Ur Aslam, Junaid Jony, Jaljalalul Abedin Aida, Maha Nur Mengmeng, Chu Hussain, Shahzada Qamar Park, Sangheon Khan, Alamgeer Khokhar, Muhammad Quddamah Yousuf, Hasnain Department of Electrical and Computer Engineering Sungkyunkwan University Gyeonggi-do Suwon16419 Korea Republic of Department of Physics COMSATS University Islamabad Lahore Campus Lahore54000 Pakistan Interdisciplinary Program in Photovoltaic System Engineering Sungkyunkwan University Gyeonggi-do Suwon16419 Korea Republic of Department of Future Energy Engineering Sungkyunkwan University Gyeonggi-do Suwon16419 Korea Republic of Research Institute for Clean Energy College of Information and Communication Engineering Sungkyunkwan University Gyeonggi-do Suwon16419 Korea Republic of

This research focused on synthesizing titanium dioxide (TiO2) nanomaterials using the sol-gel method to improve Silicon Heterojunction (SHJ) solar cells. Iso-Propanol Alcohol and Titanium Tetra Isopropoxides were used in the synthesis process. TiO2's wide bandgap and low work function make it a suitable replacement for these cells' n-doped amorphous silicon layer. Atomic Force Microscopy (AFM) measured the roughness and 3D profile, while UV-V spectrophotometry assessed absorption. The nanomaterials' structure and surface morphology were analyzed using Scanning Electron Microscopy (SEM) and Transmission Electron Microscope (TEM). Simulations using the AFORS-HET simulator showed that the refractive index of TiO2 and a-Si:H(n), TiO2 with a work function of 4.6 eV enhanced the solar cells' performance by 22.57%, achieving an open-circuit voltage (Voc) of 716.8 mV, a short-circuit current density (Jsc) of 37.71 mA/cm2, a fill factor (FF) of 83.49. Future work will focus on refining TiO2's nanostructure to further advance its photovoltaic applications. © 2024, The Authors. All rights reserved.

关键词： Titanium dioxide

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Circularly polarized luminescent self-organized helical superstructures:From materials and stimulus-responsiveness to applications

Aggregate

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Aggregate 2021年第6期2卷 60-81页

作者： Yanrong He Siyang Lin Jinbao Guo Quan Li Key Laboratory of Carbon Fibers and Functional Polymers Ministry of Educationand College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijingChina Institute of Advanced Materials School of Chemistry and Chemical Engineeringand Jiangsu Province Hi-Tech Key Laboratory for Biomedical ResearchSoutheast UniversityNanjingChina Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program Kent State UniversityKentOhioUSA

Circularly polarized luminescence(CPL)has gained considerable attention in various systems and has rapidly developed into an emerging research *** meet the needs of actual applications in diverse fields,a high luminescence dissymmetry factor(glum)and tunable optical performance of CPL would be the most urgent pursuit for ***,many emerging CPL materials and various strategies have been developed to address these critical *** cholesteric liquid crystals(CLCs),that is,luminescent self-organized helical superstructures,are considered to be ideal candidates for constructing CPL-active materials,as they not only exhibit high glum values,but also enable flexible optical control of *** review mainly summarizes the characteristics of CPL based on CLCs as the bulk phase doped with different emitters,including aggregated induced emission molecules,conventional organic small molecules,polymer emitters,metal-organic complex emitters,and luminescent *** addition,the recent significant progress in stimulus-responsive CPL based on emissive CLCs in terms of several types of stimuli,including light,electricity,temperature,mechanical force,and multiple stimuli is ***,a short perspective on the opportunities and challenges associated with CPL-active materials based on the CLC field is *** review is anticipated to offer new insights and guidelines for developing CLC-based CPL-active materials for broader applications.

关键词： amplifying dissymmetry factor cholesteric liquid crystal circularly polarized luminescence self-organized helical superstructure stimulus-responsiveness

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Optimal analysis for enhancement of thermo mechatronic processes 25

Optimal analysis for enhancement of thermo mechatronic proce...

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25th World Multi-Conference on Systemics, Cybernetics and Informatics, WMSCI 2021

作者： Calderón, J. Alan Lozano, John Tafur, Julio Barriga, Benjamín Lengua, Juan Carlos Solano, Gonzalo Huanca, Darío Applied Nanophysics Institute for Physics Technical University of Ilmenau Ilmenau98693 Germany Engineering Department Mechatronic Master Program Pontificia Universidad Católica del Peru Lima15088 Peru Federal University Arkhangelsk163002 Russia

ISBN: (纸本)9781713835196

Thermodynamic processes are part of the road of a thermodynamic system, while it has an initial and final state of the thermal trajectory. Nevertheless, there are many intricate variables while the process goes from a transient to a steady state, in many contexts it causes imbalances in the final system, such as given losses in internal efficiencies of subsystems from the main system, furthermore the total losses in the system efficiency. Hence, in this work is proposed a procedure to optimize a general thermodynamic process which was evaluated in different applications that are part of primary manufacturing tasks like there are in Perú, even they can produce pollution or disturbances in nature conditions when it is not an optimal procedure to develop the thermodynamic process. This proposal procedure is based in mathematical modelling by correlation in theoretical analysis of the thermal system with analysis of experimental data through adaptive/predictive techniques, moreover, it was evaluated and suggested applications of new technologies as sensors/actuators based in nanostructures due to faster and robust characteristics as comparisons with traditional sensors/actuators. Finally, the results achieved were interpreted by standards norms that help to keep based comparisons to interchange with international community. © WMSCI *** right reserved.

关键词： Nanostructures

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Velocity-gauge Real-time Time-dependent Density Functional Tight-binding for Large-scale Condensed Matter Systems

arXiv

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arXiv 2023年

作者： Xu, Qiang Del Ben, Mauro Okyay, Mahmut Sait Choi, Min Ibrahim, Khaled Z. Wong, Bryan M. Materials Science & Engineering Program Department of Chemistry Department of Physics & Astronomy University of California-Riverside RiversideCA92521 United States Applied Mathematics & Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States

We present a new velocity-gauge real-time, time-dependent density functional tight-binding (VG-rtTDDFTB) implementation in the open-source DFTB+ software package (https://***) for probing electronic excitations in large, condensed matter systems. Our VG-rtTDDFTB approach enables real-time electron dynamics simulations of large, periodic, condensed matter systems containing thousands of atoms with a favorable computational scaling as a function of system size. We provide computational details and benchmark calculations to demonstrate its accuracy and computational parallelizability on a variety of large material systems. As a representative example, we calculate laser-induced electron dynamics in a 512-atom amorphous silicon supercell to highlight the large periodic systems that can be examined with our implementation. Taken together, our VG-rtTDDFTB approach enables new electron dynamics simulations of complex systems that require large periodic supercells, such as crystal defects, complex surfaces, nanowires, and amorphous materials. Copyright © 2023, The Authors. All rights reserved.

关键词： Gages

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Assessment of scoring functions for computational models of protein-protein interfaces

arXiv

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arXiv 2024年

作者： Sumner, Jacob Meng, Grace Brandt, Naomi Grigas, Alex T. Córdoba, Andrés Shattuck, Mark D. O’Hern, Corey S. Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Chemistry Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States Department of Chemistry Duke University DurhamNC27708 United States Department of Physics Duke University DurhamNC27708 United States Benjamin Levich Institute Physics Department City College of New York New YorkNY10031 United States Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States

A goal of computational studies of protein-protein interfaces (PPIs) is to predict the binding site between two monomers that form a heterodimer. The simplest version of this problem is to rigidly re-dock the bound forms of the monomers, which involves generating computational models of the heterodimer and then scoring them to determine the most native-like models. Scoring functions have been assessed previously using rank- and classification-based metrics, however, these methods are sensitive to the number and quality of models in the scoring function training set. We assess the accuracy of seven PPI scoring functions by comparing their scores to a measure of structural similarity to the x-ray crystal structure (i.e. the DockQ score) for a non-redundant set of heterodimers from the Protein Data Bank. For each heterodimer, we generate re-docked models uniformly sampled over DockQ and calculate the Spearman correlation between the PPI scores and DockQ. For some targets, the scores and DockQ are highly correlated;however, for many targets, there are weak correlations. Several physical features can explain the difference between difficult- and easy-to-score targets. For example, strong correlations exist between the score and DockQ for targets with highly intertwined monomers and many interface contacts. We also develop a new score based on only three physical features that matches or exceeds the performance of current PPI scoring functions. These results emphasize that PPI prediction can be improved by focusing on correlations between the PPI score and DockQ and incorporating more discriminating physical features into PPI scoring functions. © 2024, CC BY.

关键词： Monomers

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Exploring the non-Hermitian topology of exceptional points in lasers and fiber loops

Exploring the non-Hermitian topology of exceptional points i...

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2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023

作者： Schumer, Alexander Nasari, Hadiseh Liu, Yuzhou G.N. Lopez-Galmiche, Gisela Leshin, Jason Lopez-Aviles, Helena E. Ding, Lei Alahmadi, Yousef Hassan, Absar U. Zhong, Qi Rotter, Stefan LiKamWa, Patrick Christodoulides, Demetrios N. Khajavikhan, Mercedeh ViennaA-1040 Austria Ming Hsieh Department of Electrical and Computer Engineering University of Southern California Los AngelesCA90089 United States CREOL The College of Optics & Photonics University of Central Florida OrlandoFL United States Center of Excellence for Telecomm Applications Joint Centers of Excellence Program King Abdul Aziz City for Science and Technology Riyadh11442 Saudi Arabia Department of Physics & Astronomy University of Southern California Los AngelesCA United States

ISBN: (纸本)9798350345995

When non-Hermitian eigenvalue surfaces form intertwined Riemann surfaces, the corresponding non-Hermitian singularities, also know as exceptional points (EPs), are located at the center of this specific topology. Various experimental platforms have recently been presented in which interesting new physics associated with these branch point singularities can be explored. In particular, it has been shown that dynamically encircling EPs may lead to a so-called chiral state transfer. The chirality in this context refers to the fact that in such an encircling protocol, the final state at the end of an EP-enclosing loop solely depends on the encircling direction (clockwise or counterclockwise), but not on the initial state. Such a chiral behavior is intrinsically linked to the state vector deviating from adiabatically following the system's eigenstates associated with the eigenvalue surfaces;instead, due to the non-Hermitian violation of the adiabatic theorem, non-adiabatic jumps let the system undergo transitions from lossy eigenstates to eigenstates with gain. Here, we present two experiments that implement concepts that go beyond this established paradigm. © 2023 IEEE.

关键词： Topology

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