Thickness Of Dielectric Material Research Articles

Enhancement of absorption property of one-dimensional ternary periodic structure containing plasma based hyperbolic material for the application of microwave devices

Abstract This work reports a theoretical analysis of the absorption properties of a one-dimensional ternary periodic structure of dielectric, silicon dioxide and hyperbolic materials using well-known simple transfer matrix method (TMM). The hyperbolic material is a composite material of dielectric and plasma materials in which the optical constants of hyperbolic material have been studied by considering the effective medium theory. The relative permittivity of hyperbolic material has been studied with the variation of filling fraction and the electron collision frequency. The absorption of ternary periodic structure was studied with varying incident angle, in which the maximum absorption is found at incident angle 80°. Therefore, we have studied the absorption spectra of the considered periodic structure with variation of filling fraction, electron collision frequency, and thickness of dielectric material where the incident angle is constant at 80° for the maximum absorption. In this particular case, we have obtained the enhanced absorption spectra for ternary periodic structure in comparison to other angle of incidence at low normalized frequency. However, zero absorption for the same structure is obtained at the high normalized frequency range that exhibits a band gap. Now, the enhanced absorption of the considered structure has been studied with variation of filling fraction, electron collision frequency and thickness of dielectric material. We have obtained that the enhanced high absorption at the low microwave frequency may be used as a sensor, detector, logic gate; and the absorption band gap at the high microwave frequency range may as tunable absorber based microwave devices.

Optical Properties of Planar and Annular Ternary Superconducting Photonic Crystals in Near-Zero-Permittivity Operation Range

Optical properties of ternary superconducting planar/annular photonic crystals composed of a high-temperature superconductor and two dielectrics were theoretically investigated based on transfer matrix methods in Cartesian and cylindrical coordinates. Electrodynamics of superconductor were modelled using two-fluid model. It is of interest to observe that, for a planar structure, there exists an additional high reflectance band termed as superpolariton gap near the superconducting threshold wavelength for the TM wave at oblique incidences and some reflection dips also were found in the TM reflectance. However, the superpolariton gap and reflection dips were seen for an annular geometry at higher order azimuthal number. For an annular structure, the size of superpolariton gap can be controlled by simply adjusting the starting radius. Moreover, the superpolariton gap in both structures strongly depends on the operating temperature, different combinations of dielectric refractive indices, and thicknesses of dielectric materials.

Effects of reactor geometry on dissociating CO2 and electrode degradation in a MHCD plasma reactor

AbstractThis paper reports an experimental study on the effects of reactor geometry for dissociating carbon dioxide using a microhollow cathode discharge (MHCD) reactor, and the associated electrode degradation. A MHCD reactor consists of two hollow metal electrodes that are separated by dielectric material. The geometric reactor parameters studied were the dielectric material thickness and the diameter of the reactor hole. Dielectric thicknesses of 150, 300 and 450 μm and discharge hole diameters of 200, 400 and 515 μm were studied parametrically. The results of each parameter combination were discussed in terms of specific energy input (SEI), CO2 conversion, electrical‐to‐chemical energy conversion efficiency, and degradation rate of the electrodes. Overall, the results showed that, at constant SEI, increasing the dielectric thickness increased CO2 conversion and energy efficiency but decreased the degradation rate. Moreover, at a constant SEI, varying the hole diameter did not affect CO2 conversion or efficiency but the electrode degradation rate decreased with increasing hole diameter. The maximum efficiency observed was about 18.5% for the dielectric thickness of 450 μm, hole diameter of 400 μm, and a SEI of 0.1 eV/mol. With this reactor geometry, the maximum CO2 conversion was 17.3% at a SEI of 3.7 eV/mol. Moreover, the results showed that the rate of electrode degradation increased linearly with time at a rate ranging from 130 to 207 μm2/s, with a reactor lifetime of 13 hours at a SEI of 3.7 eV/mol. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

Realization of forming-free Ag/ZrO2-based threshold selector with high selectivity by optimizing film thickness and scaling down electrode size

The influence of the switching layer thickness and the device size on the threshold switching characteristics has been investigated in Ag/ZrO2/Pt selector device. By optimizing the switching layer thickness, excellent threshold switching characteristics such as forming-free behavior, high selectivity and good endurance was achieved. In addition, we revealed the impact of active metal electrode diffusion on the device performance as the thickness of dielectric material scaled. A two-step set behavior was also observed in the device with 80 nm switching layer under a high compliance current of 1mA. Furthermore, the selectivity was increased highly by decreasing electrode size. In particular, the selectivity was about 2×108 when the electrode size was scaled down to 300 nm.

High-resolution pulsed electro-acoustic (HR PEA) measurement of space charge in outer space dielectric materials

The pulsed electro-acoustic (PEA) method is used for thirty years for measuring space charge distribution in dielectric materials [1]. However, this method was limited to at least 150 μm thick films characterization. For some applications, in spatial industry for example, 50 μm thick outer space dielectric materials must be analyzed. A high resolution optimized measurement system is discussed in this paper in order to expand performances and ranges of this method. To design it, a new pulse generator has been conceived and an optimized acoustic detector, key of the PEA method, has been realized and validated. The optimized High-Resolution PEA apparatus allows to obtain calibration signal with 50 μm thick dielectric materials that can be used to obtain the characteristic transfer function of the PEA system, essential step to use the data processing to find space charge distribution to characterize thinner dielectric materials.

Performance Degradation of Cavity Backed Patch Antenna Due to Dielectric Coating and Its Improvement

The cavity backed patch antenna embedded in dielectric coated structure is presented. The patch antenna is backed by a substrate integrated cavity. The aperture of antenna is surrounded by a thick dielectric material which acts as dielectric coating and significantly deteriorates impedance matching and radiation pattern of antenna. The radiation pattern of antenna is severely degraded due to excitation of surface waves in the surrounding dielectric coating. The proposed electromagnetic bandgap (EBG) structure in the form of via less metallic patches is placed on the surrounding dielectric coating. The EBG structure reduces the propagation of surface waves in the dielectric coating causing improvement in the radiation pattern of antenna. The input impedance matching of antenna is also improved. The simulated results are in good agreement with experimental results.

Radome-covered substrate-integrated cavity-backed patch antenna surrounded by dielectric material

The substrate-integrated cavity-backed patch antenna embedded in dielectric-coated structure is presented. The aperture of antenna is covered with composite radome. The close proximity of radome to antenna severely degrades input impedance matching. The dielectric coating, a thick dielectric material, significantly deteriorates radiation pattern of antenna due to propagation of surface waves in the surrounding dielectric coating. The proposed planar electromagnetic bandgap structure reduces the propagation of surface waves in the dielectric coating recovering deterioration in the radiation pattern of the antenna. The problem of input impedance mismatching of antenna is resolved by placing a metallic strip on the top of the radome. The simulated results are in good agreement with measured results.

Photonic band gap in a one-dimensional periodic structure with semiconductor metamaterial in the near infrared

We construct a one-dimensional photonic crystal (1DPC) by use of semiconductor metamaterial in the near infrared which is composed of Al-doped ZnO (AZO) and ZnO and dielectric material. The expressions of transmittance and field distribution are deduced by transfer matrix method, and the dispersion curves of anisotropic permittivity of semiconductor metamaterial are analyzed at different ratio of AZO and ZnO. At last simulation results are given to analyze the influence of thickness of dielectric material and incident angle on the transmittance of the proposed PC.

Silicon Nanowire Based MOSFET Parameter Analysis

Abstract: As the conventional silicon metal-oxide-semiconductor field-effect transistor (MOSFET) approaches its scaling limits many novel device structures are being extensively explored. Among them, the silicon nanowire transistor (SNWT) has attracted broad attention from both the semiconductor industry and academia. To understand device physics in depth and to assess the performance limits of SNWTs, simulation is becoming increasingly important. The objectives of this paper are to assess the performance of SNWTs. A nano device simulator called fettoy was utilized for this purpose. The various output parameters analyzed were Quantum capacitance vs. gate voltage, Drain current vs. gate voltage, drain current vs. drain voltage, Drain induced barrier lowering, Threshold swing, Carrier injection velocity, on current, off current, Output conductance, Transconductance and Voltage gain for variation in input parameters like Dielectric materials, Thickness of dielectric material, Diameter of silicon nanowire and Gate Control Parameter. Also the effect of temperature was also studied.

Optimization of Dielectric Barrier Discharge Plasma Actuators for Active Aerodynamic Flow Control

This paper presents the results of a parametric experimental investigation aimed at optimizing the body force produced by single dielectric barrier discharge plasma actuators used for aerodynamic flow control. A primary goal of the study is the improvement of actuator authority for flow control applications at higher Reynolds number than previously possible. The study examines the effects of dielectric material and thickness, applied voltage amplitude and frequency, voltage waveform, exposed electrode geometry, covered electrode width, and multiple actuator arrays. The metric used to evaluate the performance of the actuator in each case is the measured actuator-induced thrust which is proportional to the total body force. It is demonstrated that actuators constructed with thick dielectric material of low dielectric constant produce a body force that is an order of magnitude larger than that obtained by the Kapton-based actuators used in many previous plasma flow control studies. These actuators allow operation at much higher applied voltages without the formation of discrete streamers which lead to body force saturation.

단일갭 반투과 FFS 액정 디스플레이를 위한 최적 화소 디자인

When a dielectric layer, in-cell retarder (ICR) is formed between electrode and LC layer to get a single gap transflective fringe-field switching (FFS) display, the operating voltage (<TEX>$V_{op}$</TEX>) is highly increased due to the thickness of dielectric material. But, we also knew the phenomenon that the increasing rate of Vop is different whether the 1st common electrode was composed of plate type or slit type. In this paper, the common electrode in transmissive part was composed of slit type which had less steepness effect of the Vop and in reflective part was composed of plate type. The rubbing angle of reflective part can be adjusted properly to match the voltage dependent transmittance and reflectance.

Electrically Tunable Phase Shifters With Air-Dielectric Sandwich Structure

AbstractElectrically tunable microwave phase shifter was developed by inserting dielectric slab and piezoelectric actuator inside a waveguide. Air-dielectric sandwich structure of dielectric material and thin air gap was placed inside a waveguide, where the thickness of air gap is controlled by the actuator. Small changes in the ratio between the thickness of dielectric material and air gap induce significant changes in the effective dielectric constant of the air-dielectric sandwich structure. Phase shifts of 20∼200 degrees were realized with the dielectric materials such as (Mg, Ca)TiO3 while the thickness of air gap is changed between 0 to 30 μm by piezoelectric control. Since the dielectric ceramics has very small loss (tand ∼ 10-4) and the air gap has practically no loss, the total structure shows low insertion loss.

Numerical simulation of the fundamental mode of a magnetoplasma rod surrounded by a lossless dielectric layer

The propagation characteristics of magnetoplasma waveguide coated with a finite thickness of dielectric material are presented. Because the boundary conditions at all interfaces can be represented by the matrix equations, the characteristic equation can be obtained by successively using the matrix manipulations. The dependence relations of attenuation and dispersion of the fundamental mode with plasma frequency, collision frequency, and electron cyclotron frequency are shown.

High-resolution PEA charge distribution measurement system

The pulsed electroacoustic (PEA) method is widely known to be an excellent method for measuring the space charge distribution that accumulates in thick dielectric materials (1 to 5 mm). We have refined the PEA measurement system for use on thin dielectric materials. With FFT deconvolution to compensate for the frequency characteristics of the piezoelectric sensor, the resolution in the depth direction is improved to /spl sim/3 /spl mu/m. This improved system is thus expected to be useful for the quantitative and nondestructive measurement of the space charge distribution in dielectric films.

Space charge measurement in thick dielectric materials by pulsed electroacoustic method

The new application of pulsed electroacoustic (PEA) method to measure space charge profiles in several millimeters thick polymers such as power transmission cable was proposed. In this method, space charge profiles are detected as acoustic wave signals that are generated by the space charge profiles existing in the sample under stimulation of an electric pulse. In most polymer samples, such as cross-linked polyethylene (XLPE) widely used in XLPE cable (CV cable), however, the acoustic wave form is obviously distorted as it propagates through the thick polymer. The acoustic wave distortion cannot be negligible when applying this method directly to very thick samples (several millimeters thick). To recover the wave form and obtain the accurate space charge profiles, it is necessary to study the attenuation and dispersion characteristics of the sample and remove their effects to the propagating acoustic wave. So-called ‘‘deconvolution processing’’ using ‘‘Jacobi method’’ was employed in this report to obtain the undistorted wave form. The principle of the data processing method is introduced and some examples for recovering the wave form are given to verify the effectiveness of the data processing method.

Dielectric properties of germanium-lead-oxygen thin films obtained by R.F. sputtering

The properties of amorphous Ge-Pb-O films produced by RF sputtering have been investigated. The sputtering conditions were varied in order to obtain GePb x O 2+x thin films (0 ≤ x ≤ 1.40). The study of local order by EXAFS showed that the deposits were composed of “GeO 4” tetrahedra linked either by oxygen vertices or through a Pb 2+ cation. The dielectric characteristics at 1 kHz for a GePb 1.40O 3.40 material are: relative permittivity 17.0, dissipation factor less than 0.35%, and temperature coefficient of capacitance 85.10 −6K −1 (temperature range 20 to 70°C); the breakdown field is about 100 MV m −1 for a 0.15 μm thick dielectric material.

Millimeter wave twist reflector design aspects

A millimeter-wave twist reflector design procedure is described. An effective dielectric constant for capacitive susceptance correction for a unidirectional planar grating at the interface of free space and dielectric material in the twist reflector environment is introduced. The loss factor of the dielectric material is taken into account for the prediction of twist reflector performance. With the introduction of these corrections experimental results are found to be in close agreement with the theory. Normalized curves for the design of twist reflectors in terms of grating parameters, dielectric substrate relative permittivity, and dielectric material thickness are presented. Experimental results are given.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Dielectric Thickness Measurement Employing Heterodyne Technique

A microwave system for measuring the thickness of dielectric materials employing the heterodyne technique is described. Calibration curves relating the dc output voltage and dielectric thickness are presented for leather, glass, and cartons. The system was operated at 9 GHz. The experimental results illustrate the suitability of the technique for industrial applications.

Sensitivity and error of the thermal fluctuation method of measuring the integral temperature over the thickness of dielectric materials

Sensitivity and error of the thermal fluctuation method of measuring the integral temperature over the thickness of dielectric materials

Dielectric Loaded and Covered Rectangular Waveguide Phased Arrays

This study examines the effects of loading or covering a phased array with dielectric materials. It studies in detail the effect of dielectric geometry, dielectric constant, and sheath thickness on the wide angle array performance of an array of rectangular waveguides in the H and quasi-E plane modes of scan. We obtain numerical solutions of the integral equations describing an array covered with thick dielectric material. The results show that we can obtain a match over a wide scan angle for the array by appropriate use of dielectric geometries, and we discuss the advantages and disadvantages of several geometries.