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Different influences of Schottky metal on the strain and relative permittivity of barrier layer between AlN/GaN and AlGaN/GaN heterostructure Schottky diodes

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Chinese Physics B 2014年第2期23卷 426-430页

作者：吕元杰冯志红顾国栋敦少博尹甲运王元刚徐鹏韩婷婷宋旭波蔡树军栾崇彪林兆军 National Key Laboratory of Application Specific Integrated Circuit Hebei Semiconductor Research Institute School of Physics Shandong University

Ni/Au Schottky contacts on AlN/GaN and AlGaN/GaN heterostructures are fabricated. Based on the measured current-voltage and capacitance-voltage curves, the polarization sheet charge density and relative permittivity are analyzed and calculated by self-consistently solving Schrodinger＇s and Poisson＇s equations. It is found that the values of relative permittivity and polarization sheet charge density of AlN/GaN diode are both much smaller than the ones of AlGaN/GaN diode, and also much lower than the theoretical values. Moreover, by fitting the measured forward 1-V curves, the extracted dislocations existing in the barrier layer of the AlN/GaN diode are found to be much more than those of the AlGaN/GaN diode. As a result, the conclusion can be made that compared with AlGaN/GaN diode the Schottky metal has an enhanced influence on the strain of the extremely thinner AlN barrier layer, which is attributed to the more dislocations.

关键词： Al(Ga)N/GaN strain relative permittivity Schottky metal

Prediction on the relative permittivity of energy storage composite dielectrics using convolutional neural networks:A fast and accurate alternative to finite-element method

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iEnergy 2022年第4期1卷 463-470页

作者： Shao-Long Zhong Di-Fan Liu Lei Huang Yong-Xin Zhang Qi Dong Zhi-Min Dang State Key Laboratory of Power System Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

The relative permittivity is one of the essential parameters determines the physical polarization behaviors of the nanocomposite dielectrics in many applications,particularly for capacitive energy *** the relative permittivity of particle/polymer nanocomposites from the microstructure is of great ***,the classical effective medium theory and physics-based numerical calculation represented by finite element method are time-consuming and cumbersome for complex structures and nonlinear *** work explores a novel architecture combining the convolutional neural network(ConvNet)and finite element method(FEM)to predict the relative permittivity of nanocomposite dielectrics with incorporated barium titanite(BT)particles in polyvinylidene fluoride(PVDF)*** ConvNet was trained and evaluated on big datasets with 14266 training data and 3514 testing data generated form a programmatic *** numerical experiments,we demonstrate that the trained network can efficiently provide an accurate agreement between the ConvNet model and FEM by virtue of the significant evaluation metrics R2,which reaches as high as 0.9783 and 0.9375 on training and testing data,*** strong universality of the presented method allows for an extension to fast and accurately predict other properties of the nanocomposite dielectrics.

关键词： relative permittivity nanocomposite dielectrics convolutional neural networks finite element method prediction accuracy

On the uniqueness of virtual substrate for metasurface in a dielectric half-space

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Science China(Information Sciences) 2022年第1期65卷 207-217页

作者： Xiaobo LIU Wei XUE Xiaoming CHEN Anxue ZHANG Qiang CHENG Zongben XU School of Information and Communications Engineering Xi'an Jiaotong University School of Mathematics and Statistics Xi'an Jiaotong University State Key Laboratory of Millimeter Waves and School of Electrical Engineering Southeast University

In this paper, we study the uniqueness of a virtual substrate for periodic metallic elements in a dielectric half-space. When the periodic metallic elements are placed at the interface of different substrates,they can be regarded to be embedded into a virtual substrate whose thickness approaches zero. However,the process of the mathematical limit of the thickness seems to be independent of the choice of the virtual substrate. Thereby, it is necessary to verify whether the arbitrary virtual substrate holds for the case. It is theoretically verified that the permittivity of the virtual substrate should be unique in order to satisfy the physical boundary condition of the periodic metallic elements. The root of the phenomenon is that the mathematical limit gives the alternative means to approach the actual physical situation, but the actual physical situation determines the way how the mathematical limit approaches zero. Finally, for comparison,two different virtual substrates are designed to validate the theory, for alternative substrate, incidence angle,and metallic elements. Besides, the finding can also be used to simplify the analysis and design of the metasurface by converting the periodic metallic elements in a dielectric half-space to the same periodic metallic elements in a uniform substrate.

关键词： virtual substrate periodic metallic elements mathematical limit relative permittivity boundary condition

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Evaluation of internal void related defects in reinforced concrete slab using electromagnetic wave properties

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Earthquake Engineering and Engineering Vibration 2024年第3期23卷 525-535页

作者： Minju Kang Jinyoung Hong Taemin Lee Doyun Kim Hajin Choi School of Architecture Soongsil UniversitySeoul 06978Republic of Korea

This study aims to develop a damage-detection algorithm based on the electromagnetic wave properties inside a reinforced concrete *** proposed method involves employing two algorithms based on data measured using ground-penetrating radar—a common electromagnetic wave method in civil *** possible defect area was identified based on the energy dissipated by the damage in the frequency-wavenumber domain,with the damage localized using the calculated relative permittivity of the *** proposed method was verified through a finite difference time-domain-based numerical analysis and a testing slab with artificial *** a result of verification,the proposed method quickly identified the presence of damage inside the concrete,especially for honeycomb-like defects located at the top of the *** study has practical significance in scanning structures over a large area more quickly than other non-destructive testing methods,such as ultrasonic methods.

关键词： GPR concrete defect electromagnetic wave relative permittivity non-destructive testing(NDT)

Transformation of a metasurface on the substrate interface into the same metasurface in a homogenized substrate based on two kinds of modified Babinet's principles

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Science China(Information Sciences) 2023年第12期66卷 238-250页

作者： Xiaobo LIU Rui LU Anxue ZHANG Qiang CHENG Xiaoming CHEN School of Information and Communications Engineering Xi'an Jiaotong University School of Mathematics and Statistics Xi'an Jiaotong University State Key Laboratory of Millimeter Waves and School of Electrical Engineering Southeast University

Previously, the metasurface was usually manufactured on a dielectric substrate using the printed circuit boards(PCB) technology. However, due to the existence of the substrate interface, the electromagnetic radiation and coupling of the sub-wavelength metasurface becomes more complex for theoretical analysis. To this end, an indirect method is developed to transform the problem of a metasurface in a dielectric half-space into a simpler problem of the same metasurface in a homogenized dielectric space. Specifically, two different theoretical models of complementary metasurfaces in a dielectric half-space are first given. A specific yet unknown relative permittivity is included in one model to realize the above transformation. By comparing these two theoretical models in terms of the surface impedance matrix, the specific yet unknown relative permittivity is analytically derived as (εr,unk)1/2=(εr,1)1/2/2 +(εr,2)1/2/2. Finally, two arbitrary metasurfaces are given to verify the proposed theory for arbitrary incidence wave in dielectric half-space. The theory can greatly simplify the analysis and design of the metasurface in a dielectric halfspace, because only the metasurface in a homogenized dielectric space like vacuum needs to be theoretically solved after completing the above transformation.

关键词： dielectric half-space homogenized dielectric space metasurface relative permittivity surface impedance matrix substrate interface

relative Permittivities for Glucose+Glycine+Water Solution at 278.15 to 313.15 K

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Chemical Research in Chinese Universities 2011年第5期27卷 880-885页

作者： ZHUO Ke-lei LIU Qian-ge LIU Hong-xun LI Na-na CHEN Yu-juan School of Chemistry and Environmental Science Henan Normal University Xinxiang 453007P. R. China

The relative permittivities（ε） for the glucose＋glycine＋water mixtures were measured at temperatures of 278.15 to 313.15 K. The experimental values for a complete data set were critically analyzed. The experimental va- lues were fitted to some empirical equations as the functions of temperature and/or compositions of the solution. At given temperatures and compositions of glycine, the dependences of the relative permittivities on the molar fraction of glucose（Glc） and glycine（Gly） can be described by a linear or quadratic equation, respectively. A comparison of the εGlc values of glucose solution with the εGla values of galactose solution indicates that the relative permittivities of the ternary solutions containing glucose are smaller than those containing galactose under the same conditions. This difference arises from the slight difference in the stereo-structures of the saccharide molecules.

关键词： relative permittivity D-(+)-Glucose Glycine

Dielectric study of three homologous Schiff base ferroelectric liquid crystals with the variations of temperature and frequency

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Journal of Advanced Dielectrics 2020年第5期10卷 11-24页

作者： Vijayshree Patil N. B.N.Veerabhadraswamy Susanta Chakraborty S.M.Khened R.D.Mathad C.V.Yelamaggad Department of Physics Gulbarga University Kalaburagi 585106KarnatakaIndia Centre for Nano and Soft Matter Sciences Prof.U.R.Rao Road Jalahalli Bengaluru 560013KarnatakaIndia Department of Physics Laxmi Venkatesh Desai College Raichur 584101KarnatakaIndia Department of Physics North Bengal UniversitySiliguri Darjeeling 734013West BengalIndia

In this investigation,the dielectric behaviors of three ferroelectric liquid crystals(FLCs)belonging to a homologous series have been revealed in the frequency range of 10 Hz-10 *** used in this study are three-ring calamitic LCs,namely(S)-4-(((4-(octan-2-yloxy)phenyl)imino)methyl)phenyl 4-(n-octyloxy)benzoate,(S)-4-(((4-(octan-2-yloxy)phenyl)imino)methyl)phenyl 4-(n-decyloxy)benzoate and(S)-4-(((4-(octan-2-yloxy)phenyl)imino)methyl)phenyl 4-(n-undecyloxy)*** polarizing optical microscopic and differential scanning calorimetric results confirm that these compounds,synthesized as per the known synthetic steps,show not only a ferroelectrically switchable chiral smectic C(SmC*)phase over a wide thermal range,but also other mesophases such as blue phase-I/II(BP-I/II),chiral nematic(N*)and unknown smectic(SmX)*** essential dielectric parameters of the FLC phase have been measured at different *** relative permittivity has been measured with the variations of temperature and ***,the dielectric loss and tanδhave been *** dielectric relaxations have been calculated and explained at the molecular *** systematic measurements revealed a strong anomaly,and crossover of relative permittivity values for the FLCs has been determined at selective frequencies between 1 kHz and 20 *** dielectric anomaly/fall for the response function infers the involvement of collective response of dipolar assembly confined to ferroelectric Weiss domains.

关键词： Liquid crystal tanδ relative permittivity Maxwell-Wagner mode Goldstone mode smectic C*phase

Prediction of breakdown strength of cellulosic insulating materials using artificial neural networks

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Journal of Advanced Dielectrics 2018年第1期8卷 25-28页

作者： Sakshi Singh M.M.Mohsin Aejaz Masood Department of Electrical Engineering Z.H.College of Engineering&Technology Aligarh Muslim University AligarhUP 202002India

In this research work,a few sets of experiments have been performed in high voltage laboratory on various cellulosic insulating materials like diamond-dotted paper,paper phenolic sheets,cotton phenolic sheets,leatheroid,and presspaper,to measure different electrical parameters like breakdown strength,relative permittivity,loss tangent,*** the dependency of breakdown strength on other physical parameters,different Artificial Neural Network(ANN)models are proposed for the prediction of breakdown *** ANN model results are compared with those obtained experimentally and also with the values already predicted from an empirical relation suggested by Swanson and *** reported results indicated that the breakdown strength predicted from the ANN model is in good agreement with the experimental values.

关键词： Cellulosic materials relative permittivity loss tangent breakdown strength ANN