Thickness Of Dielectric Material Research Articles

Secondary electron emission yield in thick dielectric materials: a comparison between Kelvin probe and capacitive methods

The recent high demand of secondary electron emission yield (SEY) measurements in dielectric materials from space industry has driven SEY laboratories to improve their facilities and measurement techniques. SEY determination by the common capacitive method, also known as pulsed method, is well accepted and has given satisfactory results in most cases. Nevertheless, the samples under study must be prepared according to the experimental limitations of the technique, i.e. they should be manufactured separated from the devices representing faithfully the surface state of the own device and be as thin as possible. A method based on the Kelvin probe (KP) is proposed here to obtain the SEY characteristics of electrically floating Platinum, Kapton and Teflon placed over dielectric spacers with thicknesses ranging from 1.6 to 12.1 mm. The results are compared with those of the capacitive method and indicate that KP SEY curves are less sensitive to spacer thickness. An explanation based on the literature is also given. In all, we have established that KP is better suited for the analysis of dielectric samples thicker than 3 mm.

Dielectric response characteristics and moisture exposure evaluation of oil-paper insulation based on microstrip ring resonator

Moisture ingress significantly accelerates the aging of oil-paper insulated equipment, making accurate assessment of moisture content critical for the operation and maintenance of oil-immersed insulated power equipment. In this paper, a novel method for rapid moisture content evaluation is proposed based on a microstrip ring resonator (MRR) designed with a fundamental frequency of 1.16 GHz. A calculation model for the dielectric response analysis using MRR is established to characterize dielectric properties of the material layered on the substrate. ANSYS HFSS electromagnetic simulation software was used to study the impact of dielectric material thickness and the substrate on the MRR test results. Experimental measurement demonstrated that the maximum deviation in resonance frequency was merely 0.542 %. The dielectric properties of uniformly and non-uniformly damp insulating pressboard were analyzed across the frequency band from 1 to 6 GHz. The MRR test results were compared with those of the standard resonant cavity method and frequency domain dielectric spectroscopy (FDS) test. Using the regression algorithm and curve analysis, moisture assessment models for both uniformly and non-uniformly damp oil-paper insulation were established. The experimental results show that the MRR test can clearly distinguish between the pressboard samples with varying moisture levels under uniform conditions, with a maximum moisture evaluation error of 8.19 %. The results demonstrate that the MRR test method, requiring only 56 s, can quickly and effectively evaluate the moisture content of insulating pressboard.

Influence of Dielectric Material Thickness on the Formation of Atmospheric Plasma

This research examines the effects of dielectric material thickness and geometry on the formation of surface dielectric barrier discharge (DBD) in air. To initiate the discharge process, electrodes are connected to a high voltage source, ionizing the surrounding air and forming a thin layer of plasma near the dielectric material. The electrohydrodynamic (EHD) forces generated during this process are measured and analyzed to determine the influence of dielectric thickness and geometry on plasma formation. This study provides a more comprehensive understanding of the roles that dielectric material properties play in atmospheric plasma generation, contributing to potential optimization in the application of plasma-based technologies.

Angular surface plasmon resonance-based sensor with a silver nanocomposite layer for effective water pollution detection

For sensing various samples of polluted water and various sodium chloride concentrations using an angular surface plasmon resonance (ASPR), we have introduced a conventional structure and a hybrid heterostructure in the current research. The suggested structures are composed of silver metal, dielectric layers, silver nanocomposite, and a sensing medium. The reflectance spectra of all structures in the visible region were obtained through the utilization of the transfer matrix method by using the angular interrogation method depending on the Kretschmann configuration. Through our findings, five substrate parameters have been optimized to attain the utmost level of sensitivity across all structures: the thickness of Ag-metal, the type and thickness of dielectric materials, the host material type and the volume fraction of nanoparticles for the nanocomposite layer. In this regard, the suggested sensor provides excellent performance with a sensitivity of 448.1°/RIU\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$/\ ext{RIU}$$\\end{document}, signal-to-noise ratio of 0.787, sensor resolution of 0.284°, and figure of merit of 78.766 RIU−1. Therefore, we believe that the introduced design of our ASPR sensor presents a good candidate for an accurate and efficient detection of low concentrations of contaminated water and sodium chloride as well.

Impact of Parametric Variation on the Characteristics and Performance of CNTFET Inverter

In this paper, a simple carbon nanotube field effect transistor (CNTFET)-based inverter has been simulated and the impacts of changing various design and process parameters on its characteristics and performance have been analysed using HSPICE. The 32 nm CNTFET model of Stanford University has been used here for the simulation of the inverter. The simulation results and the voltage transfer characteristics (VTC) curve of the inverter have been extracted for (i) different channel lengths, (ii) top gate di-electric material thickness (tox), (iii) pitch value (iv) the number of tubes in CNTFET channel region and (v) chirality of the CNT. It has been observed that the VTC curve changes significantly with different values of these parameters. Some important output parameters like maximum dc current, power, rise time, fall time, average propagation delay, etc. have been measured in each case. Changes in maximum power consumption value due to the change in different parameter values are observed through plotted graphs. Output dc current vs. input voltage graphs have been plotted for different chirality of the tubes, the number of the tubes, and pitch values between n-type CNTFET and p-type CNTFET of the inverter.

Study of Non-linear Optical Properties of an ENZ Composite Metamaterial

We designed a non-linear composite metamaterial made up of sandwiched fused silica glass with silver in an alternate manner with the magnitude of thickness is adjusted so that ε'=0 in the near infrared range., and the structure’s optical behaviour is theoretically studied. It shows a shift from negative to positive in the real component of dielectric permittivity as a function of wavelength. we also have studied the variation of ENZ wavelength with thickness of dielectric layer and plasma frequency. By using the Maxwell Garnett theory, we have calculated non-linear optical properties, and we find that as we increase the thickness of dielectric material the ENZ wavelength increases along with the increases in real part of non-linear susceptibility. A significant enhancement in nonlinear parameters has been also observed at ENZ wavelength due to the ENZ nature of the composite material.

Droplet-Dispensed Graphene Oxide as Capacitive Sensing Elements for Flexible Pressure-Pulse Sensing Array

We report a novel flexible capacitive pressure-pulse sensor array developed by integrating droplet-dispensed graphene oxide (GO) sensing elements and flexible electronics. The utilization of droplet-dispensing technology enables the fabrication multiple capacitive sensing elements rapidly while producing sensitive pressure sensors with excellent repeatability. The dispensed droplet volume (GO aqueous dispersion) ranged from around 33.5 to 65.4 pL with diameter ranging from 40 to 50 μm. The size (i.e., footprint and dielectric material thickness) of a sensing element can be controlled by the total GO dispersed per droplet. The fabrication process and preliminary characterization of these GO capacitive sensors are discussed in this paper. Thus far, we have shown that these sensors have a sensitivity of ∼10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> kPa <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> , with the relative permittivity of the dispensed GO being ∼6 (measured at a frequency of 600 kHz). We have also demonstrated that the printed sensing elements can be used for human wrist pulse sensing. Hence the technology described in this paper could potentially be used in wearable electronics for healthcare applications.

The Development of Broadband Microstrip Patch Antenna for Wireless Applications

The small volume of microstrip antennas has low production costs and easy production, which has accelerated the work in this area. The disadvantages are narrow bandwidth and low gain. In wireless communication, antennas with low return loss and high bandwidth are required. The bandwidth and power gain of the microstrip patch antennas should be increased optimally. This article presents the design of the broadband microstrip patch antenna operating in the ISM 2.4 GHz band (2400-2485 MHz). The study includes three-dimensional antenna model, simulation phase and fabrication / measurement phase. For the low cost of the antenna, FR-4 with the relative dielectric constant 4.3 and the loss tangent tan 0.02 is preferred as the substrate material. Dielectric material thickness is determined as 1.6 mm. The length of the feed line and the dimensions of the rectangular patch were found by mathematical calculations with the transmission line model. There are slots on the antenna, which is a very simple method in order to improve the bandwidth, gain and directivity parameters of the antenna. In the article, four different designs are presented, the results are compared and the proposed antenna has 979 MHz bandwidth and 2.68 dBi directivity gain at -10 dB at the resonance frequency of 2.316 GHz. The changes made in the antenna design have improved the results such as gain and bandwidth compared to the conventional microstrip patch antenna. The proposed antenna is suitable for use in mobile communication.

GEOMETRIC MEASUREMENTS USING MICROWAVES

The article presents an overview of methods for measuring geometric parameters – the thickness of dielectric materials and products using ultrahigh frequency radio waves. The main methods of thickness measurement are considered: geometric, amplitude-phase, frequency-phase, ellipsometric, with examples and characteristics of their practical application. The schemes of implemented microwave thickness gauges and converters are given.

Dual-band electromagnetically induced transparent metamaterial with slow light effect and energy storage

The realization of electromagnetically induced transparency (EIT) on metamaterials has special properties, such as strong slow-light, frequency-selection and so on, which have allowed EIT to be widely used in the fields of slow-light, optical storages and filters. In this paper, a metamaterial with two pairs of split ring resonators and one cut-wire is designed to achieve dual-band EIT effect at 0.5–2.14 GHz and 0.4–2.10 GHz with independently tunable bandwidths of 1.64 GHz and 2.7 GHz, respectively. The coupled Lorentz model is adopted to principally study the coupling characteristics between dark and bright modes. It is shown that the coupling strength between the dark and bright modes could be modulated by the coupling distance, which make the dual-band transparent window could be independently modulated by only changing the coupling distance between the bright and dark mode. The group delay and energy storage are also simulated by setting the Gaussian pulse signal passing through the EIT structure. The results show that the group delay of the designed EIT structure is 16.9 times that of the same thickness of dielectric material. The manufactured metamaterial is tested in a microwave anechoic chamber. The experimental and theoretical results are well consistent. These results could be beneficial for the development of EIT research toward some up-and-coming novel slow-light, optical storage, sensor and optical filter applications.

Effect of dielectric thickness on MgZnO Thin Film Transistor characteristics

From past ten years, low-k dielectric was used as dielectric material in Thin Film Transistors Technology.Reduction of dimension of device can be done with the reduction the thickness of dielectric material and active layer. Due to reduction in thickness of dielectric material capacitances increases therefore drain current increases. But further more reduction in dielectric material leads to leakage current which effect other parameter like threshold voltage. To enhance performance of transistors without reduction in thickness of dielectric material use high-k dielectric material so overall capacitances increases and decrease leakage current. In this paper the parameters of the MgxZn1−x thin film transistors are compared. Composition of Mg in ZnO used because high direct bandgap (7.7 eV). Due to composition of Mg into ZnO that affects the electrical parameter of a transistor. MgxZn1−x (x = 20% and 1-x = 80%) Thin film transistor’s electrical performance with high-k (Al2O3(K ∼ 9)) dielectric materials thickness is measured. Variation in thickness of high-k dielectric is taken as 150 nm, 100 nm, 50 nm, 20 nm. Electrical characteristics are good for 20 nm thickness of Al2O3 dielectric material. Optimized electrical parameter of transistor like threshold voltage, mobility, and on/off ratio are 0.59 V, 9.62 cm2/V.s, and 1010 observed after simulation on TCAD. Results shows that this type of results for Thin film Transistors are used in photodetector application.

Investigating the effective radiative cooling performance of random dielectric microsphere coatings

Dielectric microsphere coatings are gaining increasing interest for passive daytime radiative cooling (PDRC) owing to their potential in mass production and low cost. Understanding the relationship between sphere parameters and their mechanisms of infrared thermal emission and solar reflection may greatly widen the design of microsphere coatings suitable for PDRC applications. In this work, the relationship between microsphere parameters (radius r, fill rate f, thickness t and environment) and PDRC performance is studied. Dielectric sphere in air can scatter more light in the solar spectrum. Maximum solar reflectance (R¯solar) can be obtained when r = 0.5 μm and thermal emittance (ε¯LWIR) in the atmosphere's long-wave infrared (LWIR) transmission window is mainly determined by the effective thickness of dielectric material due to the small sphere compared with infrared wavelengths. The optimal cooling performance based on the single-size sphere can be obtained as R¯solar = 0.949 and ε¯LWIR = 0.919 when r = 0.5 μm, t = 300 μm and f = 0.6. Furtherly by controlling the two-size sphere distribution, the cooling performance at t = 300 μm can be enhanced as R¯solar = 0.961 when r1 - r2 = 0.5 μm - 0.2 μm, and ε¯LWIR is almost the same. In addition, R¯solar can be further enhanced as large as 0.986 on the Al substrate at t = 300 μm, resulting in a net cooling power of 80 W/m2.

Coding DGS resonator sensor for ultra-high Q-factor dielectric thickness detection

In this paper, a high Q-factor-based defective ground structure (DGS) etched microwave resonator is demonstrated to identify the unknown thickness of non-destructive monolayer dielectric material. The proposed structure consists of coupled sharp-edged split-square resonator (CS-SSR), a high-impedance microstrip line, and symmetrically coded DGS optimized by adaptive genetic algorithm (AGA), which is evaluated through simulation and experiment assessment. AGA is applied to obtain ultra-high quality factor (Q-factor) using a robust calculation model with rapid convergence speed. The high Q-factor leads to high sensitivity, better accuracy, and enhanced resolution of the microwave sensor. Furthermore, the comparison of the results between the codeless, asymmetrical, and symmetrical DGS resonator illustrates that the symmetrical coding DGS resonator with higher sensitivity and better performance for dielectric material thickness detection sensors.

An investigation into the performance of structural composite capacitor by Taguchi method

Structural capacitors are multifunctional structural materials that provide structural strength and energy storage together and aim to reduce greatly the weight of a system. In this paper, the effect of dielectric separator materials such as poly(vinyl chloride) (PVC) and biaxially oriented polypropylene, the weave structure of carbon (C) fabric and the thickness of dielectric material on the multifunctional performance of structural capacitors was investigated. In order to plan experiments, analyze and interpret results and optimize factors (dielectric separator material, carbon fabric weave type, dielectric material thickness) that affect the multifunctional performance, design of experiments (DOE) was used. DOE was carried out using the Taguchi method. Structural capacitor materials were manufactured according to an experimental layout based on Taguchi’s L6 orthogonal array and were mechanically and electrically tested to evaluate their multifunctional efficiency. In addition, optimal combinations of factor levels were determined, and the optimum performance that can be obtained with these combinations was calculated by applying the Taguchi method. The results show that higher electrical and mechanical performance is obtained in the structural capacitor using twill-woven fabric. Also, in particular, PVC film, which is a widely available and low-cost polymer film, can be used as dielectric material in structural capacitors.

Characterization of silane based ultra-thin barrier deposited at elevated temperature

In this work, we describe a quick turn-around characterization approach of ultra-thin layers on low dielectric constant (Low-K) interlevel dielectric using Electrochemical Impedance Spectroscopy (EIS). It is demonstrated on an organo-silane based ultra-thin Cu barrier layer, deposited from liquid phase at elevated temperatures, 90 °C - 150 °C, using high flash temperature solvents: N-methyl-2-pyrrolydone (NMP, Tflash-point = 91 °C) or Ethylene glycol (EG, Tflash-point = 116 °C). Three Silane (Head group) based monomers; with three different tail groups (e.g. amine, aniline and methacrylate) were investigated; The elevated temperature deposition process allowed shorter deposition times (less than 15 min), compared to previous publications. Additionally, the high flash point solvents reduce the risk of spontaneous explosion or ignition. All three monomers yielded satisfactory barrier against copper transport, being tested for more than 10 h at temperature higher than 400 °C, on all substrates. The need for a quick turn-around and a simple way to determine the barrier presence, its thickness and its coverage, lead to explore the application of Electrochemical Impedance Spectroscopy (EIS). We demonstrate the capability of that method estimating thickness and coverage of such ultra-thin barriers deposited on relatively thick (~200 nm) Low-K dielectric materials. It was found that EIS below 10 Hz at negative wafer bias vs. the electrolyte reference, the impedance real part was affected by the ultra-thin layer on thick dielectric materials allowing to define an Effective Electrical Coverage (EEC) of the films on Low-K dielectric similar to what has already been defined on bare silicon. The EEC is a figure of merit and its relation to the actual surface coverage, and barrier properties, is briefly discussed.

A modified capacitance model of shunt micro switch based on MEMS technology in actuation mode: simulation and analytical study

In this paper, a modified mathematical model for capacitance analysis of micro-electro-mechanical switch based on Agarwal’s Model has been presented. This model is applicable in the condition when the micro-switch is supplied with electrostatic voltages. Effects of perforated structure and fringe field are accounted for accurate capacitance analysis of the micro-switch. The switch parameters such as thickness of dielectric material and actuation voltage for micro switch have also been considered in the present study. The switch is designed and simulated using COMSOL Multiphysics tool and results obtained through simulations have been validated using MATLAB software. It is found that the results obtained by simulation and mathematical model are in agreement closely for the presented study. This model could be used for evaluation of capacitance in downstate of the micro-switch for symmetric structures.

Multichannel filter application of a magnetized cold plasma defect in periodic structure of ZnS/TiO2 materials

In this article, transmission spectra of multilayer structure of zinc sulfide (ZnS) and titanium dioxide (TiO2) with defect of magnetized cold plasma (MCP) have been calculated theoretically by using characteristics transfer matrix method. The transmission spectra versus frequency have been analyzed for symmetric and asymmetric structure. Due to have a multiple band gaps in the asymmetric structure, we have taken the asymmetric structure for analysis with the parameters of MCP and the thicknesses of the dielectric materials. It is well known that magnetized cold plasma is an abnormal material because the permittivity changes with applied external magnetic field, and shows tunable photonic band gap for permittivity of the MCP. Now, the transmission spectra of the asymmetric structure versus frequency by inserting one or two magnetized cold plasma layer were analyzed with the variation of incident angles, the parameters of MCP, and the thicknesses of ZnS and TiO2 material. The analyzed transmission spectra of asymmetric structure with the variation of electron density, thicknesses of dielectric materials were obtained better results with defect of two plasma layers as compare to the defect of one layer of plasma. These obtained results reveal that the defect of two magnetized cold plasma layers of one dimensional asymmetric structure of ZnS, TiO2 may be used for the tunable multichannel filter at microwave region.

Increase of capacitance of thick dielectrics by fringe effect

For a capacitor with defined geometry, dimensions, and dielectric material, the capacitance normally cannot be changed. In this work, we found the apparent capacitance can be significantly increased by adding one or more electrodes to the lateral surfaces of dielectric materials, especially for the materials with large thickness/width ratio. The increase of capacitance is attributed to the capacitance formed by the small gaps between the lateral and top or bottom electrodes, which can response to the applied field due to the fringe effect. For a capacitor with thick dielectric material, the capacitance of the fringe capacitors, which are in parallel to the capacitor formed between the top and bottom electrodes, can be larger than the capacitance without lateral electrode, and increases the apparent capacitance.

Mathematical model to predict the characteristics of polarization in dielectric materials: The concept of piezoelectrcity and electrostriction

Model was developed for the prediction of polarization characteristics in a dielectric material exhibiting piezoelectricity and electrostriction based on mathematical equations and MATLAB computer simulation software. The model was developed based on equations of polarization and piezoelectric constitutive law and the functional coefficient of Lead Zirconate Titanate (PZT) crystal material used was 2.3×10-6 m (thickness), the model further allows the input of basic material and calculation of parameters of applied voltage levels, applied stress, pressure, dielectric material properties and so on, to generate the polarization curve, strain curve and the expected deformation change in the material length charts. The mathematical model revealed that an application of 5 volts across the terminals of a 2.3×10-6 m thick dielectric material (PZT) predicted a 1.95×10-9 m change in length of the material, which indicates piezoelectric properties. Both polarization and electric field curve as well as strain and voltage curve were also generated and the result revealed a linear proportionality of the compared parameters, indicating a resultant increase in the electric field yields higher polarization of the dielectric materials atmosphere.

Development of High-Efficiency Gyro-TWT With a Nonuniform Dielectric-Loaded Circuit

This paper presents the development of highly efficient gyrotron traveling-wave tube (gyro-TWT) with a nonuniform dielectric-loaded interaction circuit. The high-quality electron beam has been generated by curved-profile magnetron injection gun (MIG). With regard to the profile optimization, simulated annealing algorithm (SAA) and genetic algorithm (GA) are applied. An electron beam with a pitch factor of 1.6 and low-axial velocity spread of 0.9182% have been obtained. The parametric sensitivity is discussed in detail. A nonuniform dielectric-loaded circuit has been employed to suppress both global oscillations and local oscillations. Different thicknesses of dielectric materials have been manufactured and measured, demonstrating the circuit loss of oscillation modes that are enough for stable operation. The interaction circuit is analyzed under the guidance of nonlinear self-consistent theory and particle-in-cell (PIC) codes. The tube achieves a saturated peak output power of 36.24 kW at 93 GHz, corresponding to a saturated gain of 54 dB and a maximum efficiency of 45.3% within a 3-dB saturated bandwidth of 5 GHz.