Measurements Of Electrical Properties Research Articles

Investigation of Nondestructive and Noncontact Electrical Characterization of GaN Thin Film on ScAlMgO4 Substrate Using Terahertz Time‐Domain Spectroscopic Ellipsometry with Characteristic Impedance Analytical Model

Semiconductor evaluation methods frequently require sample processing and carry the risk of defects and property changes. Therefore, nondestructive and noncontact electrical property measurement techniques are necessary. Terahertz time‐domain spectroscopic ellipsometry (THz‐TDSE) can simultaneously estimate the electrical properties and film thickness of a sample. However, whether this method can simultaneously determine electrical properties and film thickness for semiconductor thin films of 1 μm or less remains unclear. This study uses THz‐TDSE to evaluate the electrical properties and film thickness of a GaN thin film (≈0.8 μm thick) on a ScAlMgO4 substrate. Using the conventional analysis based on Fresnel's formula (FR model), which is used in the field of optics, uniquely determining the electrical properties and film thickness is not possible owing to multiple optimal solutions. Therefore, a model combining the characteristic impedance model used in the radio‐wave region with the FR model is employed in the analysis. The obtained values of electrical properties of the GaN thin film evaluated using THz‐TDSE are consistent with those using Hall effect measurement. Moreover, the film thickness is consistent with that measured from the cross‐sectional transmission electron microscopy observation.

The ferroelectric and piezoelectric properties of (Hf1-x Ce x )O2 films on indium tin oxide/Pt/TiO x /SiO2/(100)Si substrates obtained using a no-heating radio-frequency magnetron sputtering deposition method

Abstract The effect of composition and film thickness on the ferroelectric and piezoelectric properties of (Hf1-x Ce x )O2 films deposited without substrate heating was investigated. (Hf1-x Ce x )O2 films with various x values (x=0.07–0.27) and thickness (150–880 nm) were deposited via radio-frequency (RF) magnetron sputtering on indium tin oxide (ITO)/Pt/TiO x /SiO2/(100)Si substrates. The crystalline phases of the films were observed by X-ray diffraction. The measurements of electrical properties revealed ferroelectric phases in the x range of 0.11–0.21. The film with x=0.16 exhibited the maximum remanent polarization (P r) of 15 µC/cm2, as well as the highest effective piezoelectric coefficient. In addition, the ferroelectric and structural properties remained almost unchanged with increasing film thickness. Therefore, the no-heating deposition of ferroelectric (Hf1-x Ce x )O2 films and their phase stability with respect to thickness were demonstrated for the first time. This work provides a pathway for the deposition of ferroelectric (Hf1-x Ce x )O2 films on flexible, wearable sensors.

Influence of design and annealing parameters on measurements of AC properties of NiFe-SiO2 multilayer structures

In this article, due to the exceptionally interesting electrical and magnetic properties of nanocomposites, which include ferromagnetic materials in a dielectric matrix, multilayer NiFe-SiO2 nanocomposites were obtained. The entire sequence of technological processes using magnetron sputtering equipment in the presence of argon was presented, the aim of which was to create structures with different numbers and thicknesses of layers, as well as in two measurement configurations. Measurements of AC electrical properties were carried out in a variable temperature range, i.e. from room temperature to 373 K, using the 4-point method. The obtained measurement results were compared in terms of design parameters, such as thickness and number of layers, as well as technological parameters, such as heating duration. Structural analysis was performed using scanning electron microscopy (SEM) to investigate the effect of oxidation on the multilayer structures and to confirm the granular structure of the nanocomposite. Additionally, the chemical composition of the obtained multilayers was examined using Energy-dispersive X-ray spectroscopy (EDX). Resistive parameters were tested in the range of magnetic field induction from 0 T to 0.3 T. Based on the conductivity relationships, it was proven that a hopping mechanism of current conduction occurs in the tested samples. Using the frequency dependencies of the phase shift angle, it is possible to adjust the equivalent RC electronic circuit, thereby determining the potential application of the tested materials.

Fabrication of Gadolinium Oxide-doped Fe2O3-LaFeO3-La2O3 Thick Films by Screen Printing Technique and Their Electrical Properties for Ethanol Gas Sensors

Recently, there have been many researchers who discussed screen printing techniques (SPT) as a good approach to fabricate the thick films for gas sensor applications. In this work, the SPTs were conducted to fabricate the thick films based on gadolinium oxide-doped Fe2O3-LaFeO3-La2O3 that were applied as ethanol gas sensors. The crystal and morphological structures were investigated using x-ray diffraction and scanning electron microscopy, respectively. It shows that there are three phases of the crystal structure of gadolinium oxide-doped Fe2O3-LaFeO3-La2O3 i.e., rhombohedral, orthorhombic, and hexagonal. The morphological structure shows an average particle size of about 0.61 μm. Furthermore, the electrical properties measurements were explored to ensure the performance of thick films in detecting the ethanol gases. Th measurements were conducted in the range of temperature of about 310 ∘C to 325 ∘C and in the various ethanol gas containing, it is 0 ppm, 100 ppm, 200 ppm, and 300 ppm. This result showed that the highest response of thick films in the existence of ethanol gases (300 ppm) is 427 with an optimum temperature of 319 ∘C. It is also confirmed that SPT has an excellent approach in thick film fabrication to produce gas sensor devices with good performance.
 Keywords: fabrication, gadolinium oxide, doped, thick films, screen printing, electrical properties, ethanol, sensors

Design of Electrical Sheet Resistance of Thin Film Measurement System Based on GM Cryocooler in Cryogenic Temperature

The determination of the dependencies of the electrical resistivity of the thin film to temperature is of great importance both for understanding the conduction mechanism and for numerous technical applications of these films. In this work, to characterize, the electrical properties of thin films, a GM cryocooler-based automatic board temperature range electrical properties measurement system has been constructed. The system can measure multiple samples simultaneously. The cooling process was simulated using the time-discrete differencing to validate the optimized device design parameters and minimize heat losses. Furthermore, the temperature-dependent sheet resistance results were compared with the results from the physical property measurement system.

An Inductive Method for Comprehensive Estimation of Temperature-Dependent Electrical and Thermal Properties of Conductive Ferromagnetic Materials

Reliable information about the properties of the processed materials has a significant impact on the effects of their processing. In induction heating processes, this also applies to information about the influence of temperature T on these properties. These are both thermal and electro-magnetic properties. Based on previous studies, a comprehensive experimental method is presented for estimating the temperature characteristics of thermal diffusivity, volumetric heat capacity and resistivity on one measurement station, with particular attention to ferromagnetic materials. The estimation process is carried out on an induction heating stand using forcing signals from an inverter generator. In a computer-controlled cycle that changes the base temperature level, basic measurements of thermal and electrical properties are carried out on a material sample in the form of a cylindrical disk. They are the results of the analysis of the temperature and electromagnetic responses of a material sample to short- and long-term step pulses of a sinusoidal excitation signal with a frequency of approximately 40 kHz. The presented estimation method can be treated as a final method or a preliminary procedure for radically narrowing the variability in decision variables inthe optimization process of simultaneous determination of the sought material characteristics.

Effect of co‐substitution on complex thermoelectric compounds: The Zintl phase Ba1‐xSrxZn2‐yCuySb2 system

AbstractThree co‐substituted quaternary and quinary Zintl phases belonging to the Ba1‐xSrxZn2‐yCuySb2 (x = 0, 0.09; 0.24 ≤ y ≤ 0.42) system were prepared by the molten Pb metal‐flux method. Co‐substitution using the cationic Sr and anionic Cu for Ba and Zn was initially applied to lower the thermal conductivities and to improve the electric conductivities of these title compounds simultaneously. The homogeneities of single‐phase products were verified by powder x‐ray diffraction analysis, and the BaCu2S2‐type orthorhombic crystal structures with the Ba/Sr and the Zn/Cu mixed‐sites were refined by single crystal x‐ray diffraction analysis. Structural selectivity for the observed BaCu2S2‐type phase was rationalized by the radius ratio of cationic and anionic elements, where r+/r− > 1. DFT calculations using the three structural models revealed that the Sr and Cu substitutions can increase the structural stability and the hole carrier concentration. A series of temperature‐dependent electrical transport property measurements for BaZn1.76Cu0.24Sb2 and Ba0.91Sr0.09Zn1.70Cu0.30Sb2 successfully proved that the co‐substitution using Sr and Cu enhanced electrical conductivities, but reduced the Seebeck coefficients resulting in the slight change in power factor.

ZnSb Films on Flexible Substrates: Stability, Optical Bandgap, Electrical Properties, and Indium Doping

AbstractUndoped and In‐doped ZnSb thin films are deposited on rigid glass and flexible polyimide (Kapton) by physical vapor deposition. Detailed structural and chemical characterization is performed along with measurement of electrical and optical properties. These properties are very similar for films on glass and Kapton. Flexible ZnSb films show remarkable stability of electrical and optical properties, which are unchanged after 104 cycles of linear bending with surface strain 0.18%. Only severe flexing after this treatment (torsional bending with surface strain 1.7%) causes progressive degradation of conductivity over tens to hundreds of cycles. The ZnSb optical direct gap is determined to be 0.89 ± 0.05 eV. The optical direct gap of β Zn4Sb3 was 1.07 ± 0.05 eV. Other absorption features in the films, including smaller indirect gaps, are discussed.

Infrared Signatures for Phase Identification in Hafnium Oxide Thin Films.

Phase identification in HfO2-based thin films is a prerequisite to understanding the mechanisms stabilizing the ferroelectric phase in these materials, which hold great promise in next-generation nonvolatile memory and computing technology. While grazing-incidence X-ray diffraction is commonly employed for this purpose, it has difficulty unambiguously differentiating between the ferroelectric phase and other metastable phases that may exist due to similarities in the d-spacings, their low intensities, and the overlapping of reflections. Infrared signatures provide an alternative route. However, their use in phase identification remains limited because phase control has overwhelmingly been accomplished via substituents, thereby convoluting infrared signatures between the substituents and the phase changes that they induce. Herein, we report the infrared optical responses of three undoped hafnium oxide films where annealing conditions have been used to create films consisting primarily of the ferroelectric polar orthorhombic Pca21, antipolar orthorhombic Pbca, and monoclinic P21/c phases, as was confirmed via transmission electron microscopy (TEM), UV-visible optical properties, and electrical property measurements. Vibrational signatures acquired from synchrotron nano-Fourier transform infrared spectroscopy (nano-FTIR) are shown to be capable of differentiating between the phases in a nondestructive, rapid, and nanoscale manner. The utility of nano-FTIR is illustrated for a film exhibiting an antiferroelectric polarization response. In this sample, it is proven that this behavior results from the Pbca phase rather than the often-cited tetragonal phase. By demonstrating that IR spectroscopy can unambiguously distinguish phases in this material, this work establishes a tool needed to isolate the factors dictating the ferroelectric phase stability in HfO2-based materials.

Unveiling the effect of Gd3+ doping on enriching the structural, magnetic, optical, and dielectric properties of biocompatible hematite nanoparticles

This work is an attempt to obtain gadolinium-doped hematite GdxFe2−xO3 (x = 0, 0.05, and 0.1) using the hydrothermal method followed by heat treatment. The work also studies the impact of gadolinium doping on the magnetic, electrical, and optical properties of hematite. X-ray diffraction (XRD) analysis, energy-dispersive X-ray spectroscopy (EDAX) and photoelectron spectroscopy (XPS) showed that the obtained phase for all samples was pure hematite with no evidence of secondary phases, indicating a high solubility limit of gadolinium ions in hematite lattice. The morphology and size distribution of the particles were investigated using high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). It was found that the lattice parameters increased with increasing gadolinium concentration. Magnetization was not enhanced whereas, the coercivity decreased considerably. From UV–Vis diffuse reflection spectroscopy (DRS) measurements, the band gap energies of pure and doped α-Fe2O3 decreased from 2.01 to 1.94 eV respectively. Moreover, measurements of electrical properties showed that the dielectric permittivity decreased while the resistivity increased with increasing the gadolinium content. In addition, sulforhodamine B (SRB) test against oral epithelial cell lines showed low cytotoxicity of the particles. Finally, gadolinium doped hematite is introduced as a novel, environmentally benign material for potential applications in various fields including photocatalysis for water treatment, biosensor and as an antibacterial agent.

Glycerol-treated polypropylene/carbon black nanocomposites: Analysis of electrical, rheological, thermal and mechanical properties

Electrically conductive nanocomposites based on polypropylene (PP) were prepared using carbon black (CB) nanoparticles via melt blending in the presence of glycerol and castor oil as hydroxyl functional dispersing aids and maleic anhydride–grafted polypropylene (MAgPP) as a compatibilizer. Initially, electrical conductivity of PP/CB nanocomposites with different dosages of both CB nanoparticles and dispersing aids were investigated through electrical analysis. Results indicated that castor oil had no beneficial effects on electrical conductivity. However, the efficiency of 3 wt% loading of glycerol was verified through measurements of electrical, rheological, thermal and mechanical properties as well as by morphological studies. The volume electrical conductivity value of PP nanocomposites containing 12 wt% CB significantly enhanced to 1.2 × 10−4 S/cm by adding 3 wt% glycerol in compared with nanocomposite without glycerol with the volume conductivity value of 1.8 × 10−6 S/cm. Incorporation of optimum amount of glycerol favoured the dispersion of nanofiller in the matrix which was confirmed by scanning electron microscopy observations, leading to higher conductivity due to better formation of conductive pathways within the matrix. Additionally, at the same concentration of CB nanofiller, samples treated with 3 wt% glycerol showed higher melting temperatures, storage modulus ( Gˊ), complex viscosity, tensile modulus and elongation at break. These findings indicate that adding an optimum amount of an efficient hydroxyl functional component like glycerol into PP/CB nanocomposite can be a promising way to enhance the electrically conductive performance while other properties could be maintained well or even improved.

Photocurrent performance and enhancement of opto-electronic properties of spray pyrolysis deposited ZnO thin films via V-doping

This study reports on the deposition of highly transparent conducting n-type zinc oxide (ZnO) thin films on FTO substrates, via an optimized doping process. Our work is focused on doping zinc oxide with vanadium (V) using spray pyrolysis technique and ensure the synthesis of nanoparticles-shaped ZnO, with an improved optical, microstructural and electrical properties for solar cells applications, as optical window material. Undoped and V-doped ZnO thin films, with careful optimized amounts (2, 4, 6 and 8 at.%), were grown at maintained 550∘C pre-heated substrate during the deposition process, which enables us to obtain nano-sized ZnO particles. We proved that 4 at.% is the optimum V content that enhances the crystallinity of the grown thin film noticeably. With an average transmittance of 80%, the deposited thin films revealed high transparency in the visible domain with a slight decrease in optical transmission which might result from additional scattering. UV-Visible analysis showed that increasing V amounts, a resulting decrease in the energy bandgap ([Formula: see text]) is obtained from 3.26[Formula: see text]eV to 3.17[Formula: see text]eV for 4 at.% of V content. Moreover, deep level defects in zinc oxide can be reduced with vanadium doping and consequently strengthen the UV emission. The UV emission peak intensity rises with increasing V-doping amount then decreases slightly at 8% of V content. The electrical properties measurements showed a decrease in resistivity from 2.8 10[Formula: see text][Formula: see text][Formula: see text][Formula: see text]⋅[Formula: see text]cm to 0.9 10[Formula: see text][Formula: see text][Formula: see text][Formula: see text]⋅[Formula: see text]cm when doping with 4 at.% of V. The crucial effect of the V-doping of ZnO was also demonstrated via the enhancement of carrier mobility that attains 38.5[Formula: see text]cm2/V[Formula: see text]⋅[Formula: see text]s at the optimum vanadium content. The photocurrent analysis revealed much higher visible light absorption in the V-doped zinc oxide thin films than that of undoped film. The photocatalytic activity enhancements are attributed to the lower recombination rate of the photogenerated electron-hole pairs, the narrowed bandgap, yielding a higher photocatalytic performance.

Superior piezoelectricity in lead-free barium titanate piezoceramics

Since the 21st century, increasing environmental protection and human health concern have been the driving force to develop lead-free piezoelectric materials with enhanced performances, and phase engineering strategy has been validated to be a viable method in numerous methodologies. Here, we gained a superb d33∼(637 ± 30) pC/N in lead-free (1–x)(Ba0.93Ca0.07)(Sn0.08Ti0.92)O3-x(Sb0.5Li0.5)TiO3 [abbreviated as (1–x)BCST-xSLT, 0 ≤ x ≤ 0.4% (in mole)] piezoelectrics utilizing chemical doping. To illustrate the relationship among composition-structure-performance, microstructure characterization, electrical properties measurement, first-principles calculation, and phase-field simulations were performed. Atomic-resolved polarization mapping of z-contrast imaging manifests the ferroelectric three phases (RO–T) coexist at the nanoscale with nanoscale polarization switching among them. Theoretical calculations and simulations confirm that the high-density nano-domain boundary bridges the polyphase coexisting nano-domains, which makes the polarization reversal easy, thus significantly reducing the energy barrier and polarization anisotropy among different phases.

Dielectric and electrical properties measurement of BCTO and Co & V-doped BCTO synthesized via semi-wet route method

Dielectric and electrical properties measurement of BCTO and Co & V-doped BCTO synthesized via semi-wet route method

Enhanced gas sensing capabilities of diamond layers using Au nanoparticles

The nanocrystalline diamond (NCD) film reveals a unique combination of physical, chemical, and optoelectronic properties, which makes it a promising material for various sensing applications. To improve a gas sensor's response, selectivity, or reproducibility, its surface is often modified with specific terminations, functional groups or (bio)molecules, thin films, etc. In this work, the NCD surface modification was achieved by a) layer morphology variation using two different types of chemical vapor deposition (CVD) systems, b) top surface termination (H-NCD and O-NCD), and c) Au nanoparticles (Au NPs). The properties of each structure are measured, compared and subsequently evaluated. The electrical properties (resistance changes) are measured for two types of active gas (oxidizing gas NO2 and reducing gas NH3) in a temperature range from 22 °C to 125 °C. Neutral synthetic air (80 % nitrogen and 20 % oxygen) was applied for flushing and resetting the sensors. Thin film fabrication, surface analysis (scanning electron microscopy and Raman spectroscopy), and measurement of electrical properties are described. Surface morphology greatly influences gas response because a large active surface area (higher roughness or 3D-like surface) enhances interaction with gas molecules. While the termination of the NCD with hydrogen is essential for the functionality of the gas sensor, the Au NPs further enhanced the dynamic response of the sensor and magnitude.

Removing of cationic dyes using self-cleaning membranes-based PVC/nano-cellulose combined with titanium aluminate

This research used the phase inversion approach to construct polyvinyl chloride nanocellulose@titanium aluminate nanocomposite membranes (PVC/NC@TALCM) to adsorb and filter dye from wastewater. FTIR, XRD, and SEM were used to determine the adsorptive nanocomposite membrane that had been synthesized. The thermal and electrical properties measurements were carried out using a static system. The influence of several adsorbent dosages, pH, and dye concentrations on the nanocomposite membrane’s adsorption ability was investigated. Using a dead-end filtration system, the PVC-NC@TALCM was evaluated as a pressure filtration membrane system. It was found that 98.6% of MB dye was removed by PVC-NC@TALCM membrane, which was loaded with 5% titanium aluminate at pH 10. The kinetic adsorption studies indicated that the adsorption of MB onto the PVC-NC@TALCM nanocomposite membrane obeys pseudo-second-order that indicates the chemosorption process. The isotherm data were described using Freundlich and Langmuir models, and the Freundlich isotherms were shown to be more closely match the experimental data than the Langmuir model. Finally, the PVC-NC@TALCM nanocomposite membrane was economical, environmentally friendly, and self-cleaning.

Novel n‐type Zintl phase thermoelectric materials: The Ca5−xRExAl2Sb6 (RE = Pr, Sm) system

AbstractTwo novel n‐type Zintl thermoelectric materials of Ca4.97(1)Pr0.03Al2Sb6 and Ca4.94(2)Sm0.06Al2Sb6 were synthesized with the addition of two types of trivalent rare‐earth metals dopants and characterized by powder and single crystal x‐ray diffraction analyses. Two title compounds adopted the orthorhombic Ca5Ga2As6‐type phase and contained seven crystallographically unique atomic positions including one particular Ca/Pr or Ca/Sm mixed‐site. The crystal structure can be described as a combination of the one‐dimensional (1D) infinite chains and the cationic elements in between the 1D chains. Electrical transport property measurements proved that Ca4.97(1)Pr0.03Al2Sb6 and Ca4.94(2)Sm0.06Al2Sb6 were indeed novel n‐type Zintl phase semiconductors with the maximum electrical conductivities of 69.51 and 75.51 S/cm at 846 K and the Seebeck coefficients of −43.26 and − 29.00 μV/K at 703 K, respectively. Density functional theory calculations proved that the successful n‐type doping should be attributed to a small margin of slight antibonding states near EF on the Sb1Sb1 crystal orbital Hamilton population (COHP) curve.

Enhancing Dielectric and Thermal Performances of Synthetic-Ester Insulating Oil via Blending With Natural Ester

Synthetic ester and blended insulating oils have attracted widespread attention owing to their great potential on performance enhancement because of the high capacity with tailorable molecular structure and mixable components. In this work, natural ester insulating oil (FR3) is blended into the synthetic tetra-ester insulating oil (KA) via mixing and oscillating. The physicochemical and electrical property measurements of the ester blends indicate the flash point, fire point, and AC breakdown voltage of KA are capable to be increased, and the dissipation factor of KA is reduceable by the addition of FR3. As expected, a series of physicochemical properties of the ester blends follow a quasi-linear relationship with the variation (in vol%) of FR3. However, the flash point (closed cup) is verified with high nonlinearity according to the results of thermogravimetric-derivative and thermogravimetric-differential scanning calorimetry (TG-DSC) tests in nitrogen. The optimized ester blend (85 vol% (KA):15 vol% (FR3)) is typically manifested by high flash point (260°C), low pour point (-51°C), low dissipation factor (1.44%), high AC breakdown voltage (76.5 kV), and high onset temperature of DSC either in nitrogen (229.99°C) or in the air (272.05°C). The activation energy is analyzed based on the Arrhenius equation, dissipation factor, and resistivity values in order to recognize the optimum ratio of the ester blends.

Electrical properties of tissues from a microscopic model of confined electrolytes

Objective. In the presence of oscillatory electric fields, the motion of electrolyte ions in biological tissues is often limited by the confinement created by cell and organelle walls. This confinement induces the organization of the ions into dynamic double layers. This work determines the contribution of these double layers to the bulk conductivity and permittivity of tissues. Approach. Tissues are modeled as repeated units of electrolyte regions separated by dielectric walls. Within the electrolyte regions, a coarse-grained model is used to describe the associated ionic charge distribution. The model emphasizes the role of the displacement current in addition to the ionic current and enables the evaluation of macroscopic conductivities and permittivities. Main results. We obtain analytical expressions for the bulk conductivity and permittivity as a function of the frequency of the oscillatory electric field. These expressions explicitly include the geometric information of the repeated structure and the contribution of the dynamic double layers. The low-frequency limit of the conductivity expression yields a result predicted by the Debye permittivity form. The model also provides a microscopic interpretation of the Maxwell–Wagner effect. Significance. The results obtained contribute to the interpretation of the macroscopic measurements of electrical properties of tissues in terms of their microscopic structure. The model enables a critical assessment of the justification for the use of macroscopic models to analyze the transmission of electrical signals through tissues.

A study on Sm2O3-doped Ba(Zr0.02Ti0.98)O3 ceramics for sensor applications

ABSTRACT Ba(Zr0.02Ti0.98)O3 (BZT) samples with various weight percentages of Sm2O3 (0.02–0.06) were synthesized and calcined at 1100°C for 4 h. Circular pellets were prepared using calcined powders and sintered at 1450°C for 2 h. The sintered and poled samples were used for the measurement of various electrical properties. Maximum piezoelectric charge constant (d 33) of 372 pC/N obtained for 0.02 wt.% Sm2O3-doped BZT. Dielectric constant (K = 15,855) at 100 Hz was found maximum for this composition at Curie temperature (T c) of 125°C. Scanning electron microscopy (SEM) study revealed a decrease in grain size with an increase in Sm2O3 content. Largely, a lower concentration of Sm2O3-doped BZT compositions with higher d 33 could be suitable for vibration sensor and accelerometer applications.