Effective Loss Tangent Research Articles

Tunable metamaterials with carrier-induced effective permittivity for active control of electromagnetic fields in semiconductor manufacturing device

Precise control of electromagnetic fields is critical in many advanced manufacturing processes, such as those used in the semiconductor industry, where device performance relies on precision and uniformity. Here, we introduce a solution to control electromagnetic fields via permittivity modulation without the limitations of resonance-based approaches, through a patterned semiconductor enabling permittivity tuning via carrier-density modulation. This carrier-responsive metamaterial (CRM) exhibits frequency-independent performance over a broad frequency spectrum and significant permittivity tunability through controlled semiconductor conductivity. Furthermore, the conductivity response and the tuning range can be easily modulated through the variation of semiconductor materials and geometrical parameters. We present an intuitive model that explains the relationship between the CRM’s structure and properties, including its effective permittivity and loss tangent. Supported by comprehensive simulations and experimental validations, our findings show that the effective permittivity can be increased by over 3.5 times with low dielectric loss across a wide frequency range. As an application, we explore the CRM’s potential in plasma control, revealing its ability to influence plasma density nearly 30% by modulating its effective permittivity, exhibiting CRM’s versatile functionality and potential impact across diverse technological domains.

Fringing field correction for spherical–rectangular microstrip antennas

This paper presents the analysis of spherical–rectangular patches using both cavity method and method of moments. A detailed procedure of cavity method is presented, including the field distribution inside the cavity, equivalent magnetic current distributions, radiation fields, effective loss tangent, and input impedance. A new fringing field correction is proposed taking into account the curvature of the patch, resulting in accurate resonance frequency.

Effect of frequencies on the change of electrical impedance in sand dunes of Ouargla region

In this paper, we put the accent on the measurement of real and imaginary parts of electrical impedance and effective loss tangent respectively z′, z″ and tgδ in sand dunes of Ouargla region at a range of frequency intervals between 4,6849×10−2 Hz and 1,8593×10+6 Hz with AC voltage of 1.000 V using the impedance spectroscopy. The experimental results revealed that the real and imaginary parts of electrical impedance and effective loss tangent have strong frequency dependence. In the frequencies range (4,6849×10−2 – 4,9385×10−1) Hz z′ < 0 and z″ change between (4,8118×10+2 × 5,0422×10+1) Ω, in the frequencies range (5,4877×10+1 – 2,3426×10+4) Hz z′change between 146,04 Ω and 4,8193 Ω and z″<0. In high frequencies range (1,2599×10+5 – 1,8593× 10+6) Hz z′ change between 4,5359 Ω and 5,0567 Ω. The effective loss tangent values increase until they reach a peak, in frequencies range between 4,6849×10−2 Hz and 2,5197×10−1 Hz, but then the remaining frequency the values decrease until they become constant. The nature of impedance electric variation indicated a possibility to knowledge the polarization of sand dunes of Ouargla region and acquaintance the frequencies when the material is passive devices or active devices. It is also possible to know the quality of equivalent electrical circuit, whether it is induction or capacitance.

An Implantable Wideband Microstrip Patch Antenna Based on High-Loss Property of Human Tissue

In this paper, an approach was designed to develop an implantable wideband microstrip patch antenna (MPA) by the high-loss property of human tissue. In order to reduce the detuning effect, an extensive investigation was conducted, demonstrating the effects of high-loss human tissue on the total quality factor (Q T ), effective relative permittivity, and effective loss tangent of the deeply implanted MPA. To the best of our knowledge, the exact three parameters for the deeply implanted MPA are firstly studied. From the evolutionary point of view, a deeply implanted MPA can be treated as a resonator with the extremely low and stable Q T . As such, its wide impedance bandwidth can be easily achieved through two inherent radiative modes of the embedded MPA under the high-loss environment. Finally, the proposed MPA will be fabricated and tested, and the final outcomes are consistent with the corresponding simulated results.

MIM capacitors as simple test vehicles for the DC/AC characterization of ALD-Al2O3 with auto-correction of parasitic inductance

Metal-insulator-metal capacitors were used for determining the DC and frequency-dependent characteristics of ultra-thin Al2O3 (Thox = 22 nm). For this purpose, a state-of-the-art insulating layer was formed using atomic deposition, which enables enhanced performance of devices and application within the back-end of line stage of a CMOS process. As part of the analysis, DC and low frequency CV measurements are used to determine the electric field to breakdown, the dominant conduction mechanisms, and the dielectric constant, whereas small-signal modelling allows for characterizing the frequency-dependent behaviour of the Al2O3 layer using LCR measurements from 100 Hz to 1 MHz. This avoids using dedicated RF test structures as for measuring S-parameters. Moreover, since it is demonstrated here that the parasitic effect of the series impedance associated with the metal electrodes is significant within this frequency range, an RLGC equivalent circuit is used to determine the intrinsic properties of the layer. In this way, the effective loss tangent and dielectric constant were straightforwardly extracted from AC data.

Electric Noise Spectra of a Near-Surface Nitrogen-Vacancy Center in Diamond with a Protective Layer

Surface noise is a detrimental issue for sensing devices based on shallow nitrogen vacancy (NV) color center diamonds. A recent experiment indicates that electric field noise is significant compared to magnetic field noise. They also found that the electric field noise can be reduced with a protective surface layer, though the mechanism of noise reduction is not well understood. We examine the effect of a protective surface layer on the noise spectrum, which is caused by surface charge fluctuations. We use the fluctuation-dissipation theorem to calculate and analyze the noise spectrum for six different surface layer materials typically used for NV center diamond devices. We find that four parameters largely affect the noise spectrum: effective relaxation time, effective loss tangent, power law exponent of the noise spectrum, and layer thickness. Our results suggest that a surface covering layer is indeed useful for decreasing surface noise, but which material is most suitable depends on the device operational frequency range.

An Implantable Circularly Polarized Patch Antenna Design for Pacemaker Monitoring Based on Quality Factor Analysis

A design approach is presented in this paper to develop an implantable circularly polarized (CP) microstrip patch antenna (MPA) embedded in a lossy material by addressing its total quality factor ( $Q_{T}$ ). To achieve it, the effect of high-loss tissue on effective relative permittivity and loss tangent of MPA has been thoroughly investigated. To the authors’ best knowledge, it is the first time that the exact values of $Q_{T}$ with respect to the high-loss tissue and embedded depth are studied and applied to design an implantable MPA. As the calculated $Q_{T}$ is confirmed in simulation, one can understand that an implantable MPA is actually a lossy resonator with extremely low $Q_{T}$ . As such, CP radiation can be achieved by enlarging its truncated area to appropriately separate two degenerate modes in such high-loss environment. The designed implantable MPA is then exhibited to achieve a broad impedance bandwidth, wide 3 dB axial ratio bandwidth and beamwidth, and high realized gain at 2.4 GHz industrial, scientific, and medical band. After the studies of sensitivity, biocompatible materials, and model integrity are carried out, the designed implantable MPA is fabricated and tested. Simulations are accompanied by measurements with good agreement, thus underlying the importance of our approach.

Substrate-Independent Microwave Components in Substrate Integrated Waveguide Technology for High-Performance Smart Surfaces

Although all existing air-filled substrate integrated waveguide (AFSIW) topologies yield a substrate-independent electrical performance, they rely on dedicated, expensive, laminates to form air-filled regions that contain the electromagnetic fields. This paper proposes a novel substrate-independent AFSIW manufacturing technology, enabling straightforward integration of high-performance microwave components into a wide range of general-purpose commercially available surface materials by means of standard additive (3-D printing) or subtractive (computer numerically controlled milling/laser cutting) manufacturing processes. First, an analytical formula is derived for the effective permittivity and loss tangent of the AFSIW waveguide. This allows the designer to reduce substrate losses to levels typically encountered in high-frequency laminates. Then, several microwave components are designed and fabricated. Measurements of multiple AFSIW waveguides and a four-way power divider/combiner, both relying on a new coaxial-to-air-filled SIW transition, prove that this novel approach yields microwave components suitable for direct integration into everyday surfaces, with low insertion loss, and excellent matching and isolation over the entire [5.15–5.85] GHz band. Hence, this innovative approach paves the way for a new generation of cost-effective, high-performance, and invisibly integrated smart surface systems that efficiently exploit the area and the materials available in everyday objects.

Prediction of electromagnetic transmission properties using dielectric property modeling of foamed concrete containing BFS

In this paper, we propose a formula for modeling dielectric properties for evaluating the electromagnetic transmission of foamed concrete (FC) widely used as building materials. This includes the effective permittivity and loss tangent according to the foam content of FC mixes containing blast furnace slag (BFS), as well as the content of the BFS, by modifying the dielectric modeling formula for porous foam materials. The difference between the permittivity calculated using the proposed modeling formula and the actual measured permittivity ranges from 0.2% to 2.6%. The calculated result and the measured value are approximately the same. The transmission properties of FC were calculated using the calculated dielectric property values. FC samples containing BFS were fabricated using different foam and BFS content, and their transmission properties were measured, the results of which coincided well with the simulation results. Therefore, the accuracy of the proposed dielectric property modeling of FC containing BFS was verified.

High Q Ba(Zn1/3Ta2/3)O3 microwave resonator in a closed cavity for sensor applications

Microwave dielectric resonator having a high Q-factor results in high sensitivity and it can be used as a sensing element in wireless passive sensor systems. In the present work, we demonstrated high Q resonator enclosed in a metallic cavity which is highly sensitive to resonance frequency and quality factor change arising from small test samples kept on the surface of the resonator. The measurements are made at the resonance frequency of TE10δ mode. The Ba(Zn1/3Ta2/3)O3 resonators prepared by solid state reaction method exhibits high Q value of >12,500. The experimental studies have been conducted on different type of rice grains cut to uniform size and shape to explore the response of resonance frequency and Quality factor. The change in effective dielectric constant and loss tangent of resonator with test samples were measured. Our work should provide a general guidance in development of high Q dielectric resonators for sensor applications.

Broadband Microwave Characterization of Nanostructured Thin Film With Giant Dielectric Response

This paper describes the extraction of the dielectric properties of a nanostructured thin film from two-port $S$ -parameter measurements on coplanar waveguide (CPW) lines. The CPW line is on top of a bilayer structure formed by a supporting glass substrate and a dielectric thin film made by dispersing silver nanoparticles inside a polymer host. A dispersion mechanism due to internal inductance of the CPW line when calculating the effective dielectric constant is investigated. The extraction involves conformal-mapping approximation that uses closed-form equations to calculate the dielectric constant and the loss tangent of each layer based on the effective dielectric constant and loss tangent of the entire structure. Additionally, computer-aided-design model with a direct fitting technique are deployed for further investigation of potential multimode propagation for a CPW line with a substrate that has a very large dielectric constant. The results of the two techniques are compared and discussed. The measured dielectric constant ranges from ${\hbox{3}}\times {\hbox{10}}^{4}$ to ${\hbox{4.6}}\times {\hbox{10}}^{3}$ from 1 to 20 GHz with a loss tangent of 0.55 to 1.75 from 1 to 20 GHz.

Analysis of elliptical-disk microstrip patch printed on isotropic or anisotropic substrate materials

This paper presents a simple approach for accurate determination of the resonant frequency of an elliptical microstrip patch printed on isotropic or anisotropic substrate materials. In this approach, some modifications are made to account for fringe fields, dispersion effects, and losses by calculating effective dimensions, effective permittivity of anisotropy in the layer, and effective loss tangent, respectively. The theoretical resonant frequency results are in very good agreement with the experimental results reported elsewhere. Numerical results show that the change in the resonant frequency of the antenna is due primarily to a small disturbance of the substrate's nature. Then the effect of the uniaxial anisotropic materials is a significant parameter and most essential on the microstrip antenna characterization.

Stress and electric field gradient contributions to dielectric loss in ferroelectrics with interdigitated electrodes

Interdigitated electrode configurations produce nonuniform electric field and stress in the vicinity of the electrodes, creating a volume where the material is not uniformly polarized. This results in enhanced hysteresis in interdigitated electrode configurations relative to the hysteresis in the bulk material. The dielectric loss in a macro-fiber composite with interdigitated electrodes was characterized and is compared to the dielectric loss of the same material under a uniform field. The dielectric loss in the interdigitated electrode arrangement was found to be significantly larger and had a strong dependence on electric field amplitude. The dielectric loss is expressed in terms of an effective loss tangent (tan δ) and a more general damping model. A mechanism that contributes to the hysteresis is that the local stress in the ferroelectric material beneath the interdigitated electrodes induces ferroelastic polarization reorientation during each electric field cycle. The interactions between polarization gradients and residual stress are assessed using a finite element model with a micromechanical-based constitutive law.

Large-field dielectric loss in relaxor ferroelectric PLZT

Lead zirconate titanate ceramics are often used at unipolar drive field levels approaching or exceeding the coercive field, yet dielectric losses are characterized by a loss tangent measured at a significantly lower drive field. As the magnitude of the drive field is increased the energy dissipation can increase significantly over that predicted by the low-field loss tangent. This experimental study addresses the effects of temperature and bias stress on large-field dielectric loss in lanthanum-doped lead zirconate titanate, Pb0.92La0.08(Zr0.65Ti0.35)0.98O3 (PLZT 8/65/35). Large-field dielectric loss was experimentally determined by measuring the area within a unipolar electric displacement–electric field hysteresis loop. The results show the effects of saturation on the effective loss tangent.

Loss Performance of Planar Interconnects on FR-4 Up to 67 GHz

This paper shows the performance of planar transmission lines (TLs) on a multilayer stack-up with a flame resistant-4 (FR-4)-based core up to 67 GHz. These lines will be used as interconnects to integrate a CMOS circuit with an antenna fabricated on FR-4 for a low-cost system-in-package solution. The attenuation characteristics of coplanar waveguide (CPW), grounded coplanar waveguide (GCPW), and microstrip lines with different configurations are investigated. The peak attenuation varies from 0.15 to 0.45 dB/mm at 60 GHz, depending on the line type and geometry. In addition, the effective permittivity and loss tangent of the multilayer stack-up are determined using CPW TLs. The overall results show that FR-4-based materials are viable candidates for packaging at the millimeter-wave frequency range if suitable line lengths are utilized.

Magnetoelectricity in CoFe2O4 nanocrystal-P(VDF-HFP) thin films

Transition metal ferrites such as CoFe2O4, possessing a large magnetostriction coefficient and high Curie temperature (Tc > 600 K), are excellent candidates for creating magnetic order at the nanoscale and provide a pathway to the fabrication of uniform particle-matrix films with optimized potential for magnetoelectric coupling. Here, a series of 0–3 type nanocomposite thin films composed of ferrimagnetic cobalt ferrite nanocrystals (8 to 18 nm) and a ferroelectric/piezoelectric polymer poly(vinylidene fluoride-co-hexafluoropropene), P(VDF-HFP), were prepared by multiple spin coating and cast coating over a thickness range of 200 nm to 1.6 μm. We describe the synthesis and structural characterization of the nanocrystals and composite films by XRD, TEM, HRTEM, STEM, and SEM, as well as dielectric and magnetic properties, in order to identify evidence of cooperative interactions between the two phases. The CoFe2O4 polymer nanocomposite thin films exhibit composition-dependent effective permittivity, loss tangent, and specific saturation magnetization (Ms). An enhancement of the effective permittivity and saturation magnetization of the CoFe2O4-P(VDF-HFP) films was observed and directly compared with CoFe2O4-polyvinylpyrrolidone, a non-ferroelectric polymer-based nanocomposite prepared by the same method. The comparison provided evidence for the observation of a magnetoelectric effect in the case of CoFe2O4-P(VDF-HFP), attributed to a magnetostrictive/piezoelectric interaction. An enhancement of Ms up to +20.7% was observed at room temperature in the case of the 10 wt.% CoFe2O4-P(VDF-HFP) sample.

Effect of field driven phase transformations on the loss tangent of relaxor ferroelectric single crystals

The effect of a bias stress induced phase transformation on the large field dielectric loss in [001] cut and poled single crystal stack actuators of (1 − x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT, x = 32) was experimentally characterized. Dielectric loss was observed to increase with compressive preload and electric field amplitude. The dielectric loss was determined by measuring the area within electric displacement vs. electric field hysteresis loops and the measured area was expressed in terms of an effective loss tangent. This approach matches the measured area within the hysteresis loop to an equivalent area ellipse in which the electric displacement lags the electric field by an amount, delta, under sinusoidal loading. The results collapse the measured loss as a function of bias stress and electric field amplitude reasonably close to a single curve. The measured dielectric loss behavior was attributed to the compressive stress preload driving a partial phase transformation from rhombohedral to orthorhombic and the electric field driving the reverse phase transformation from the stress induced orthorhombic phase to the zero stress rhombohedral phase. When the compressive bias stress partially or fully drives this phase transformation, the dielectric loss under unipolar electric field loading increases. This work is focused on quasi-static measurements. The large field dielectric loss is anticipated to be a function of frequency and temperature.

Fabrication and Characterization of CoFe2O4-Polymer Nanocomposite Thin-Films

ABSTRACTMagnetic cobalt ferrite nanoparticles provide a pathway towards nanocomposites, due to the ability to fabricate particle-matrix thin films in the submicron range. In this work flexible particulate 0-3 type thin-films, composed of magnetic CoFe2O4 particles (8-18 nm) and ferroelectric poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-HFP)) polymer, have been fabricated via multiple spin-coating. The thickness of the thin-films was controlled in the range of 500 nm to 1.2 μm, with magnetic particles dispersively embedded in the polymer matrix. Structural information was analyzed by TEM, XRD, HRTEM and SEM. The dielectric and magnetic properties of the cobalt ferrite/copolymer thin films are systematically investigated. The nanocomposite thin films exhibit composition-dependent effective permittivity and loss tangent, as well as temperature and composition-dependent specific saturation magnetization (Ms). The coercivity (Hc) was not affected by the composite’s composition. These films have great potential in smart magnetic devices and biomagnetic applications.

High Tunable ${\rm Ba}_{0.05}{\rm Sr}_{0.95} {\rm TiO} _{3}$ Thin Films for Microwave Applications at Cryogenic Temperature

La0.67Sr0.33MnO3/Ba0.05Sr0.95TiO3 (LSMO/BST) heterostructure thin film was grown on single crystal MgO substrate by pulsed laser deposition. The phase structure and dielectric properties of the film were investigated. The results show that the permittivity of the BST thin film decreased from 1170 to 350 (70% tuning) with the bias voltage increasing from 0 to 80 V at 63 K. The effective loss tangent of the BST thin film is in the range of 0.009-0.017.

Tuneability amplification factor and loss of high-contrast composites

The problem of tuneability of nonlinear ferroelectric–dielectric composite materials is addressed. Attention is concentrated on the analysis of the tuneability amplification factor, K, of a composite material, which is introduced as the ratio of the effective tuneability of a composite material to the tuneability of its ferroelectric (tuneable) component. Previously, ferroelectric–dielectric composite materials have been designed with an effective tuneability amplification factor slightly greater than 1 (i.e. 1.1–1.4) [A.K. Tagantsev et al., J. Electroceramics 11 (2003) p.5; A.G. Kolpakov et al., J. Electroceramics 18 (2007) p.129]. It is demonstrated that the tuneability amplification factor can take values significantly greater than 1. Numerical prototypes (structural designs integrated with finite element method tools) of microstructures are presented with K in the range 3 to 30. The effective tuneability of nonlinear composite materials strongly depends on the microgeometry and microtopology of the material and, in general, cannot be described in terms of volume fraction of components of composite material. In the designs presented, the increased tuneability is due to concentration of the high electric field in narrow regions with carefully selected geometry. The problem of loss in ferroelectric–dielectric composite materials is discussed. In the general case, the loss tangent stays between that of the components of the composite. For high-contrast ferroelectric–dielectric composite materials, the effective loss tangent is practically equal to the loss tangent of the ferroelectric.