Electrical Characteristics Research Articles

Fabrication and Electrical Characterization of XCP Electrode With Quasi-Nano Ag/AgCl Materials

Fabrication and Electrical Characterization of XCP Electrode With Quasi-Nano Ag/AgCl Materials

Measuring Electrical Resistivity at the Nanoscale in Phase-Change Materials.

Electrical resistivity is the key parameter in the active regions of many current nanoscale devices, from memristors to resistive random-access memory and phase-change memories. The local resistivity of the materials is engineered on the nanoscale to fit the performance requirements. Phase-change memories, for example, rely on materials whose electrical resistance increases dramatically with a change from a crystalline to an amorphous phase. Electrical characterization methods have been developed to measure the response of individual devices, but they cannot map the local resistance across the active area. Here, we propose a method based on operando electron holography to determine the local resistance within working devices. Upon switching the device, we show that electrical resistance is inhomogeneous on the scale of only a few nanometers.

Investigating the Application and Impact of Laser Etching Technology in the Fabrication of Solar Cells

The most crucial initial step in the metallization process of electroplating is the local contact openings in dielectric layers. In this article, an ultraviolet picosecond laser (UV‐ps), is used to open the front and back dielectric layer of the precursor of n‐TOPCon solar cells. By changing the laser parameters and spot overlap rate, the surface morphology of laser etching under different conditions is obtained and characterized by optical microscope and scanning electron microscope. The results indicate that there are three separate laser shock zones in the dielectric layer under the action of Gaussian light spot, and the corresponding ablation mechanisms are proposed. The longitudinal distribution of B element is characterized by secondary ion mass spectrometry to explore the effect of laser on its pn junction. In addition, the electrical characterization of lifetime photoluminescence is measured and calibrated using WCT120, and this indicates that the majority of the amorphous silicon is recrystallized when applying a fast firing oven process, and this hence improve the minority carrier lifetime and implied open‐circuit voltage. The laser damage to the emitter at the laser‐ablated regions is investigated using the emitter saturation current density, J0laser extracted by WCT120.

Inhibition of mTOR prevents glucotoxicity-mediated increase of SA-beta-gal, p16INK4a, and insulin hypersecretion, without restoring electrical features of mouse pancreatic islets.

An over-activation of the mechanistic target of rapamycin (mTOR) pathway promotes senescence and age-related diseases like type 2 diabetes. Besides, the regenerative potential of pancreatic islets deteriorates with aging. Nevertheless, the role of mTOR on senescence promoted by metabolic stress in islet cells as well as its relevance for electrophysiological aspects is not yet known. Here, we investigated whether parameters suggested to be indicative for senescence are induced in vitro in mouse islet cells by glucotoxicity and if mTOR inhibition plays a protective role against this. Islet cells exhibit a significant increase (~ 76%) in senescence-associated beta-galactosidase (SA-beta-gal) activity after exposure to glucotoxicity for 72h. Glucotoxicity does not markedly influence p16INK4a protein within 72h, but p16INK4a levels increase significantly after a 7-days incubation period. mTOR inhibition with a low rapamycin concentration (1nM) entirely prevents the glucotoxicity-mediated increase of SA-beta-gal and p16INK4a. At the functional level, reactive oxygen species, calcium homeostasis, and electrical activity are disturbed by glucotoxicity, and rapamycin fails to prevent this. In contrast, rapamycin significantly attenuates the insulin hypersecretion promoted by glucotoxicity by modifying the mRNA levels of Vamp2 and Snap25 genes, related to insulin exocytosis. Our data indicate an influence of glucotoxicity on pancreatic islet-cell senescence and a reduction of the senescence markers by mTOR inhibition, which is relevant to preserve the regenerative potential of the islets. Decreasing the influence of mTOR on islet cells exposed to glucotoxicity attenuates insulin hypersecretion, but is not sufficient to prevent electrophysiological disturbances, indicating the involvement of mTOR-independent mechanisms.

Novel ionic liquid systems based on three-nitro phenoxide: Spectroscopic and electronic characterization using theoretical and experimental study

After extensive computations, novel trinitro compounds, triethyl ammonium 2,4,6-trinitro phenoxide (TEA-TNP) and tetramethyl guanidinium 2,4,6-trinitro phenoxide (TMG-TNP), are designed, synthesized, and identified. The Geometrical parameters, electronic properties, and spectroscopic analysis have been investigated by comparison of theoretical and experimental methods. Spectrum features that include IR and Raman have been calculated, and 1H and 13C NMR spectra are compared to experimental data. Electronic analysis has been investigated through NLO, FMO, UV-Vis, NBO, and MEP calculations. B3LYP/6-311++G(d,p) is highly successful and dependable for predicting ionic liquid stability, electrical characteristics, and spectroscopy. Both TEA-TNP and TMG-TNP are introduced as suitable candidates for NLO material. TMG-TNP with greater nucleophilicity (N) is a noncorrosive lubricant additive that reduces friction and wear for tribological performance.

An experimental investigation of spin-on doping optimization for enhanced electrical characteristics in silicon homojunction solar cells: Proof of concept

The pursuit of enhancing the performance of silicon-based solar cells is pivotal for the progression of solar photovoltaics as the most potential renewable energy technologies. Despite the existence of sophisticated methods like diffusion and ion implantation for doping phosphorus into p-type silicon wafers in the semiconductor industry, there is a compelling need to research spin-on doping techniques, especially in the context of tandem devices, where fabricating the bottom cell demands meticulous control over conditions. The primary challenge with existing silicon cell fabrication methods lies in their complexity, cost, and environmental concerns. Thus, this research focuses on the optimization of parameters, such as, deposition of the spin on doping layer, emitter thickness (Xj), and dopant concentration (ND) to maximize solar cell efficiency. We utilized both fabrication and simulation techniques to delve into these factors. Employing silicon wafer thickness of 625 μm, the study explored the effects of altering the count of dopant layers through the spin-on dopant (SOD) technique in the device fabrication. Interestingly, the increase of the dopant layers from 1 to 4 enhances efficiency, whereby, further addition of 6 and 8 layers worsens both series and shunt resistances, affecting the solar cell performance. The peak efficiency of 11.75 % achieved in fabrication of 4 layers dopant. By using device simulation with wxAMPS to perform a combinatorial analysis of Xj and ND, we further identified the optimal conditions for an emitter to achieve peak performance. Altering Xj between 0.05 μm and 10 μm and adjusting ND from 1e+15 cm−3 to 9e+15 cm−3, we found that maximum efficiency of 14.18 % was attained for Xj = 1 μm and ND = 9e+15 cm−3. This research addresses a crucial knowledge gap, providing insights for creating more efficient, cost-effective, and flexible silicon solar cells, thereby enhancing their viability as a sustainable energy source.

Low-loss α-tantalum coplanar waveguide resonators on silicon wafers: fabrication, characterization and surface modification

Abstract The performance of state-of-the-art superconducting quantum devices is currently limited by microwave dielectric loss at different interfaces. α-tantalum is a superconductor that has proven effective in reducing dielectric loss and improving device performance due to its thin low-loss oxide. Here, we demonstrate the fabrication of high-quality factor α-tantalum coplanar-waveguide resonators directly on pristine 300 mm silicon wafers over a variety of metal deposition conditions and perform a comprehensive material and electrical characterization study. Additionally, we apply a surface treatment based on hydrofluoric acid that allows us to modify different resonators surfaces, leading to a reduction in two-level system (TLS) loss in the devices by a factor of three. This loss reduction can be entirely attributed to the removal of surface oxides. Our study indicates that large scale manufacturing of low-loss superconducting circuits should indeed be feasible and suggests a viable avenue to materials-driven advancements in superconducting circuit performance.

Enhancing photoelectrochemical properties of α-Fe2O3 using Zr-doped HfO2 ferroelectric nanoparticles

Hematite (α-Fe2O3) as a semiconductor photoanode for photoelectrochemical (PEC) water splitting is a promising candidate material. However, its PEC performance is limited by the slow charge transfer kinetics at the α-Fe2O3/electrolyte interface. Ferroelectric materials can be used as a tool for carrier separation in photoelectrochemical water splitting due to their spontaneous polarization electric field characteristics. Here, we deposited Hf0.5Zr0.5O2 (HZO) ferroelectric nanoparticles on the surface of α-Fe2O3 and use the spontaneous polarization field of ferroelectric HZO to promote the separation of photogenerated carriers, promote the charge transfer from α-Fe2O3 to the electrolyte, and enhance the PEC of hematite. After depositing the HZO nanoparticles, the photogenerated holes are efficiently extracted from α-Fe2O3 and then directed into the electrolyte to participate in water oxidation reaction at α-Fe2O3/HZO interfaces, which enhanced the charge separation efficiency by 58 % compared to that of pure α-Fe2O3. Consequently, the α-Fe2O3/HZO photoanode exhibits a 65 % boost in photocurrent density, reaching up to 0.28 mA cm−2 at 1.23 V versus the reversible hydrogen electrode (VRHE) compared to that of pure α-Fe2O3. This study introduces a method to engineer the photoanode/ferroelectric interface, enhancing carrier separation and thereby optimizing PEC water splitting performance.

Experimental and Simulation Studies on Stable Polarity Reversal in Aged HVDC Mass-Impregnated Cables

Mass-impregnated (MI) cables have been used for many years as cables in high-voltage direct current (HVDC) systems. In line commutated converter (LCC) HVDC systems, polarity reversal for power flow control can induce significant electrical stress on MI cables. Furthermore, the mass oil and kraft paper comprising the impregnated insulation have significantly different coefficients of thermal expansion. Load fluctuations in the cable lead to expansion and contraction of the mass, creating pressure within the insulation and causing redistribution of the impregnant. During this process, shrinkage cavities can form within the butt gaps. Since the dielectric strength of the cavities is lower than that of the surrounding impregnation, cavitation phenomena in impregnated paper insulation are considered a factor in degrading insulation performance. Consequently, this study analyzes the electrical conductivity of thermally aged materials and investigates the transient electric field characteristics within the cable. Additionally, it closely analyzes the formation and dissolution of cavities in MI cables during polarity reversal based on a numerical model of pressure behavior in porous media. The conductivity of the impregnated paper indicates that it has excellent resistance to thermal degradation. Simulation results for various load conditions highlight that the interval of load-off time and the magnitude of internal pressure significantly influence the cavitation phenomenon. Lastly, the study proposes stable system operation methods to prevent cavitation in MI cables.

Metal Nanogap Memory: Performances and Switching Mechanism.

The nanogap memory (NGM) device, emerging as a promising nonvolatile memory candidate, has attracted increasing attention for its simple structure, nano/atomic scale size, elevated operating speed, and robustness to high temperatures. In this study, nanogap memories based on Pd, Au, and Pt were fabricated by combining nanofabrication with electromigration technology. Subsequent evaluations of the electrical characteristics were conducted under ambient air or vacuum conditions at room temperature. The investigation unveiled persistent challenges associated with metal NGM devices, including (1) prolonged SET operation time in comparison to RESET, (2) the potential generation of error bits when enhancing switching speeds, and (3) susceptibility to degradation during program/erase cycles. While these issues have been encountered by predecessors in NGM device development, the underlying causes have remained elusive. Employing molecular dynamics (MD) simulation, we have, for the first time, unveiled the dynamic processes of NGM devices during both SET and RESET operations. The MD simulation highlights that the adjustment of the tunneling gap spacing in nanogap memory primarily occurs through atomic migration or field evaporation. This dynamic process enables the device to transition between the high-resistance state (HRS) and the low-resistance state (LRS). The identified mechanism provides insight into the origins of the aforementioned challenges. Furthermore, the study proposes an effective method to enhance the endurance of NGM devices based on the elucidated mechanism.

Optical and electrical evaluation methods of plasma-induced damage in InP substrates

Abstract Indium phosphide (InP) has been focused on as one of emerging materials that can be implemented in advanced semiconductor devices. We proposed optical and electrical characterization methods to evaluate plasma-induced physical damage (PPD)—ion bombardment damage—to InP substrates. By introducing a native oxide phase in an interfacial layer, we proposed an optical model of the damaged structure applicable for an in-line monitoring by spectroscopic ellipsometry. Gas species dependence was obtained, which suggested that the H2 plasma exposure formed a thicker damaged layer than Ar. An impedance spectroscopy (IS) under various biases (V b) was implemented to reveal the nature of damaged structures. Capacitive and conductive components assigned by the IS were confirmed to depend on incident species from plasma, indicating the difference of the energy profile of created defects. The presented methods are useful to characterize and control PPD in designing future high-performance InP-based devices.

Tuning the Electronic Characteristics of Monolayer MoS2‐Based Transistors by Ion Irradiation: The Role of the Substrate

AbstractThis study explores defect engineering in 2D materials using ion beam irradiation to modify the electrical and optical properties with potential in advancing quantum electronics and photonics. Helium and neon ions ranging from 5 to 7.5 keV are employed to manipulate charge transport in monolayer molybdenum disulfide (MoS2). In situ electrical characterization occurs without vacuum breakage post‐irradiation. Raman and photoluminescence spectroscopy quantify ion irradiation's impact on MoS2. Small doses of helium ion irradiation enhance monolayer MoS2 conductivity in field‐effect transistor geometry by inducing doping and substrate charging. Findings reveal a strong correlation between the electrical properties of MoS2 and the primary ion used, as well as the substrate on which the irradiation occurred. Using hexagonal boron nitride (h‐BN) as a buffer layer between MoS2 flake and SiO2 substrate yields distinct alterations in electrical behavior subsequent to ion irradiation compared to the MoS2 layer directly interfacing with SiO2. Molecular dynamics simulations and density functional theory provide insight into experimental results, emphasizing substrate influence on measured electrical properties post‐ion irradiation.

Extraordinary Electrical Conductance through Amorphous Nonconducting Polymers under Vibrational Strong Coupling.

Enhancing the electrical conductance through amorphous nondoped polymers is challenging. Here, we show that vibrational strong coupling (VSC) of intrinsically nonconducting and amorphous polymers such as polystyrene, deuterated polystyrene, and poly(benzyl methacrylate) to the vacuum electromagnetic field of the cavity enhances the electrical conductivity by at least 6 orders of magnitude compared to the uncoupled polymers. Remarkably, the observed extraordinary conductance is vibrational mode selective and occurs only under the VSC of the aromatic C-H(D) out-of-plane bending modes of the polymers. The conductance is thermally activated at the onset of strong coupling and becomes temperature-independent as the collective strong coupling strength increases. The electrical characterizations are performed without external light excitation, demonstrating the role of vacuum electromagnetic field-matter strong coupling in enhancing long-range transport even in amorphous nonconducting polymers.

МЕТОДИКА РОЗРАХУНКУ ЗОН ПОКРИТТЯ ЦИФРОВОГО ТЕЛЕВІЗІЙНОГО МОВЛЕННЯ

The introduction of DVB-T2 digital television broadcasting in the VHF waveband is currently underway, and test trials have already been conducted in some regions of Ukraine. To assess the effectiveness of the projects, it is of particular interest to compare the radio coverage areas of digital TV transmitters operating in the VHF and UHF wave bands. This requires extensive calculations for specific locations. For comparison, the city of Kyiv was chosen, where there is one multiplex MX-7 (8 TV channels) in the VHF band, and the following four multiplexes are represented in the UHF band: MX 1 (26 TV channels) and MX 3 (49 TV channels), which operate at the lowest and highest frequencies of the band. In this article, to predict the coverage areas of digital television broadcasting transmitters, the justification of the selected Longley-Rice radio wave propagation model is provided, which allows calculating the radio signal attenuation compared to free space propagation using terrain profiles (digital elevation maps) and the electrical characteristics of the Earth's surface, Taking into account the main mechanisms of radio wave propagation (interference on the line of sight, diffraction on irregular terrain, tropospheric scattering), it is more accurate and its results are closer to actual measurements. The calculations will be carried out using Radio Mobile software based on the Longley-Rice Irregular Terrain Model (ITM) and using Terrain Mission SRTM satellite maps with the possibility of further adding map data and roads from various sources. Based on the ITU R Recommendations on the design of DVB-T2 digital television broadcasting networks, the minimum required field strength to ensure reception with a given quality was calculated and the initial data for predicting the coverage areas of DVB-T2 digital television transmitters were prepared using the example of Kyiv. The proposed methodology and the data obtained will allow to calculate the boundaries of the coverage areas of DVB-T2 digital standard television transmitters in the VHF and UHF wave bands for selected television channels

Numerical and experimental investigation of temperature dependence vs. mobility degradation on I–V characteristics in N-LDMOS structure

The thermal behavior analysis is undoubtedly the main concern when studying semiconductor devices' and structures' physical mechanics. To the best of our knowledge, simulations studies with an experimental validation of the temperature effect vs. mobility on electrical characteristics in semiconductor devices, specifically in LDMOSFET devices are not well explored in the research literature. Considering this, this paper investigates the thermal influence vs. mobility degradation in the N-LDMOS structure and its impact on electrical performance. It also addresses the temperature impact on channel current Ids and these effects on component performance. The zero-temperature coefficient (ZTC) is evaluated in a N-LDMOS structure using numerical simulations and experimental tests. A study of the drain current behavior at ZTC (IZTC) is proposed in the linear and saturation regions. The influence of temperature mobility degradation on IZTC is analyzed. The consequences of mobility degradation show that the temperature increase gives rise to two contradictory phenomena: firstly, the channel current Ids increases when its value is lower than the current level (IZTC) and secondly, decreases when is higher. These two phenomena are studied by using simulated and experimental approaches, in order to extract and prove the physical aspects near the gate-drain access region (hot spot, electric field, electron concentration, surface carrier density, electron mobility), at the parameter evaluation origin, using SILVACO-TCAD based numerical simulation. Mobility degradation due to the temperature effect is compared to the critical value in N-LDMOS based on I–V behavior obtained with experimentation and simulations. This is explained by the role of negative thermal coefficient in LDMOS transistors. This coefficient proves to be particularly beneficial in terms of mobility gain at low inversion densities.

Managing Interfacial Defects and Charge-Carriers Dynamics by a Cesium-Doped SnO2 for Air Stable Perovskite Solar Cells.

A high-quality nanostructured tin oxide (SnO2) has garnered massive attention as an electron transport layer (ETL) for efficient perovskite solar cells (PSCs). SnO2 is considered the most effective alternative to titanium oxide (TiO2) as ETL because of its low-temperature processing and promising optical and electrical characteristics. However, some essential modifications are still required to further improve the intrinsic characteristics of SnO2, such as mismatch band alignments, charge extraction, transportation, conductivity, and interfacial recombination losses. Herein, an inorganic-based cesium (Cs) dopant is used to modify the SnO2 ETL and to investigate the impact of Cs-dopant in curing interfacial defects, charge-carrier dynamics, and improving the optoelectronic characteristics of PSCs. The incorporation of Cs contents efficiently improves the perovskite film quality by enhancing the transparency, crystallinity, grain size, and light absorption and reduces the defect states and trap densities, resulting in an improved power conversion efficiency (PCE) of ≈22.1% with Cs:SnO2 ETL, in-contrast to pristine SnO2-based PSCs (20.23%). Moreover, the Cs-modified SnO2-based PSCs exhibit remarkable environmental stability in a relatively higher relative humidity environment (>65%) and without encapsulation. Therefore, this work suggests that Cs-doped SnO2 is a highly favorable electron extraction material for preparing highly efficient and air-stable planar PSCs.

Achieving optimal balance: tuning electrical and optical characteristics of carbon electrodes for emerging photovoltaics.

Transparent and conductive electrodes (TCEs) are essential for various optoelectronic and photovoltaic applications, but they often require expensive and complex fabrication methods. In this paper, a unique low-cost, eco-friendly, and scalable method of fabricating TCEs using spray-coated carbon ink is investigated. Firstly the carbon particles used for this process underwent a size reduction from 20 microns to 0.96 microns via ball milling. Then ink was prepared by mixing graphite powder (for conductivity), ethyl cellulose (for viscosity), and toluene (for solubility) with different weight-per-volume ratios (w/v) of 5%, 10%, and 15%. The TCEs were fabricated by spray coating the ink onto glass substrates using an airbrush. The sheet resistance (Ω sq-1) and transparency (%) of the TCEs were measured by a digital multimeter (DMM) probe method and a UV-vis spectrophotometer, respectively. The sheet resistance of the TCEs decreased linearly from 60 to 20 Ω sq-1, while the transparency decreased exponentially from 37.18% to 18.88% as the ink concentration increased from 5% to 15% w/v. This paper also reports the reflectance and absorbance values for each ink concentration. The results demonstrate that spray-coated carbon ink TCEs achieve sheet resistance and transparency values of 20 Ω sq-1 and 18.88%, respectively, with low-cost and eco-friendly materials and methods, which are desirable for optoelectronic and photovoltaic applications. These TCEs can play an important role as electrodes in semi-transparent perovskite cells enhancing their stability and overall efficiency.

Wave‐to‐Wire Model and Output Performance Analysis of a Point Absorption Wave Energy Converter Based on Triboelectric Nanogenerator

Herein, a point absorption wave energy converter (WEC) model combined with a contact–separation mode triboelectric nanogenerator (PAW TENG) is proposed. The model considers the interaction between the hydrodynamic forces captured by a point absorption conversion device of wave energy and the electrostatic force of the TENG. According to the established harmonic oscillation model of the buoy, the buoy's hydrodynamic properties and power generation characteristics are studied using finite element simulation and numerical simulation calculations. The best matching resistor circuit for PAW TENG in regular waves is investigated and analyzed. The electrical characteristics of the PAW TENG in the irregular wave spectrum are also solved. This work will provide design ideas for the experimental design of a novel point absorption WEC.

Reliable Lift‐Off Patterning of Graphene Dispersions for Humidity Sensors

AbstractDispersion‐based graphene materials are promising candidates for various sensing applications. They offer the advantage of relatively simple and fast deposition via spin‐coating, Langmuir–Blodgett deposition, or inkjet printing. Film uniformity and reproducibility remain challenging in all of these deposition methods. Here, a scalable structuring method is demonstrated, characterized, and successfully applied for graphene dispersions. The method is based on a standard lift‐off process, is simple to implement, and increases the film uniformity of graphene devices. It is also compatible with standard semiconductor manufacturing methods. Two different graphene dispersions are investigated via Raman spectroscopy and Atomic Force Microscopy and observe no degradation of the material properties by the structuring process. Furthermore, high uniformity of the structured patterns and homogeneous graphene flake distribution is achieved. Electrical characterizations show reproducible sheet resistance values correlating with material quantity and uniformity. Finally, repeatable humidity sensing is demonstrated with van der Pauw devices, with sensing limits of less than 1% relative humidity.

Magnesium-doped zinc oxide film for hydrogen production from wastewater

Recently, developing resources for H2 production has been a supreme priority to maintain the current rate of global warming in waste and drinking water. Metal-doped zinc oixde (ZnO) film-based catalyst materials are better candidates for electrochemical water splitting. Herein, it will be demonstrated that Mg-doped ZnO films can significantly enhance the electrochemical water splitting and H2 production. Therefore, Mg-doped ZnO films were synthesized using the dip coating technique. The undoped and Mg-doped ZnO films' structure, chemical, and morphological properties were characterized using detalied measurements. The electrical and optical characteristics of ZnO and Mg–ZnO samples were investigated. ZnO and Mg–ZnO films coated on the proper reactor were utilized for electrochemical water splitting. The efficiency of the electrochemical water splitting increases from 29 % to 56 % as ZnO is doped with Mg. In addition, the yielding H2 concentration increases from 9.92 × 10−7 mol/L.h to 3.65 × 10−6 mol/L.h when ZnO is doped with Mg. Hence, the work sheds new insight into new ways of fabricating significant photocatalysts for low-cost hydrogen extraction and echo-friendly agents.