Changes In Electrical Characteristics Research Articles

Electrical properties of epoxy/graphite flakes microcomposite at the percolation threshold concentration

The electrical properties and activation energy of epoxy/graphite flakes (GFs) micro-composite with different content of GFs (0.0625–1 wt%) were studied for electrical properties using Novocontrol Alpha Analyser (10−2 Hz—107 Hz). GFs sizes ranged from (100 nm to 10 μm). The analysis was performed by scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), visible spectrum reflectance spectra (VIS) spectra, and Fourier Transform Infrared spectra (FTIR) spectroscopy. Increasing GFs content caused multiple changes in electrical characteristics. At 0.0625 wt%, all electrical properties noticeably increased. But at 0.125 to 0.25 wt%, immobilized nanolayers were formed leading to decreased permittivity, dielectric loss (tan(δ)), quality factor (Q-factor), capacitance, conductivity, and figure of merit (F-factor). At 0.25 wt%, the epoxy microcomposite had lower permittivity, tan(δ), conductivity, and capacitance compared with unfilled epoxy. With 0.5 wt% of GFs, signified the percolation threshold, initiating a rise in permittivity, conductivity, capacitance, and tan(δ), accompanied by the closer proximity of grain boundaries, facilitating the formation of conductive channels. At a concentration of 1 wt% of GFs, the establishment of continuous interfacial conductive pathways resulted in a remarkable augmentation of all dielectric properties. The Cole-Cole analysis has been employed to investigate variations in epoxy/GFs microcomposites based on concentration levels.

MEMS sensitive structure sand and dust friction contamination test and electrical variation characteristics

The impact of dust pollution on the sensitive components of Micro-Electro-Mechanical Systems (MEMS) has been a hot topic in current reliability research. However, previous studies have rarely focused on the fundamental analysis of the influence of dust pollutants on the sensitive components of MEMS, and these research results lack universality. This paper aims to present experimental results on the electrical characteristic changes of MEMS thermal sensitive resistors based on dust friction, providing a more detailed description and explanation. Through dust friction experiments, we investigated the effects of dust particle size and relative humidity on the electrical characteristics of MEMS devices. We chose the resistance value output as the electrical characteristic parameter, based on the performance exhibited during the dust friction experiments. We conducted a detailed analysis of the reasons for the changes in the electrical characteristic parameters. The research results showed that when dust particles settle on the device, the failure mode of the device manifests as resistance drift. The inducing factor is the electrostatic current generated by the friction between dust particles, which enters the sensitive components through the principle of electrostatic dissipation. The measurement principle leads to changes in the resistance value measurement, although the actual resistance value does not change. The magnitude of this electrostatic current is directly proportional to the size of the particles and inversely proportional to the relative humidity. This finding provides theoretical guidance for identifying failure-inducing factors in MEMS failure modes.

Analysis of the Electrical Characteristic Changes of ITO Nanoparticle HNS Sensors Using a Catalyst

Analysis of the Electrical Characteristic Changes of ITO Nanoparticle HNS Sensors Using a Catalyst

Rapid and Accurate Antimicrobial Susceptibility Testing Using Label-Free Electrical Impedance-Based Microfluidic Platform.

Antimicrobial resistance has become a serious threat to the global public health. Accurate and rapid antimicrobial susceptibility testing (AST) allows evidence-based prescribing of antibiotics to improve patient care and clinical outcomes. Current culture-based AST assays are inherently limited by the doubling time of bacterial reproduction, which require at least 24 h to have a decisive result. Herein, a label-free electrical impedance-based microfluidic platform designed to expedite and streamline AST procedure for clinical practice is presented. Following a 30-min exposure of bacterial samples to antibiotics, the presented high-throughput, single-bacterium level impedance characterization platform enables a rapid 2-min AST assay. The platform facilitates accurate analysis of individual bacterial viability, as indicated by changes in electrical characteristics, thereby enabling the determination of antimicrobial resistance. Moreover, the potential clinical applicability of this platform is demonstrated by testing different E. coli strains against five antibiotics, yielding 100% categorical agreements compared to standard culture methods.

Simulation study on total ionizing dose effect of IGBT gamma irradiation

The insulated gate bipolar transistor (IGBT) has emerged as a prominent high-power semiconductor device due to its excellent overall performance. It is widely utilized in various fields, including aerospace. Due to prolonged operation in complex irradiation environments, the performance of IGBTs is susceptible to degradation and damage. Therefore, conducting research on the variation of IGBT characteristics under irradiation environments is crucial to ensuring their long-term functionality in extended space missions. To evaluate and analyze the total ionizing dose (TID) effect of IGBTs during operation, this study adopts a trench IGBT as the device model. Utilizing the finite element method, technology computer-aided design (TCAD) is employed to simulate and analyze the electrical characteristic changes of IGBTs under different total radiation doses. The simulation results are subsequently validated through theoretical analysis. The simulation results indicate that gamma radiation significantly affects the overall electrical characteristics of IGBTs.

Reversible Total Ionizing Dose Effects in NiO/Ga2O3 Heterojunction Rectifiers

NiO/Ga2O3 heterojunction rectifiers were exposed to 1Mrad fluences of Co-60 g-rays either with or without reverse biases. While there is small component of Compton electrons (600 keV), generated via the interaction of 1.17 and 1.33 MeV gamma-photons with the semiconductor, which in turn can lead to displacement damage, most of the energy is lost to ionization. The effect of the exposure to radiation is a 1000x reduction in forward current and 100x increase in reverse current in the rectifiers, which is independent of whether the devices were biased during this step. The on-off ratio is also reduced by almost 5 orders of magnitude. There is a slight reduction in carrier concentration in the Ga2O3 drift region, with an effective carrier removal rate of < 4 cm-1. The changes in electrical characteristics are reversible by application of short forward current pulses during repeated measurement of the current-voltage characteristics at room temperature. There are no permanent total ionizing dose effects present in the rectifiers to 1 Mad fluences, which along with their resistance to displacement damage effects indicate these devices may be well-suited to harsh terrestrial and space radiation applications if appropriate bias sequences are implemented to reverse the radiation-induced changes. Figure 1

Argon and Oxygen Gas Flow Rate Dependency of Sputtering-Based Indium-Gallium-Zinc Oxide Thin-Film Transistors.

Oxygen vacancies are a major factor that controls the electrical characteristics of the amorphous indium-gallium-zinc oxide transistor (a-IGZO TFT). Oxygen vacancies are affected by the composition ratio of the a-IGZO target and the injected oxygen flow rate. In this study, we fabricated three types of a-IGZO TFTs with different oxygen flow rates and then investigated changes in electrical characteristics. Atomic force microscopy (AFM) was performed to analyze the surface morphology of the a-IGZO films according to the oxygen gas rate. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis was performed to confirm changes in oxygen vacancies of a-IGZO films. The optimized a-IGZO TFT has enhanced electrical characteristics such as carrier mobility (μ) of 12.3 cm2/V·s, on/off ratio of 1.25 × 1010 A/A, subthreshold swing (S.S.) of 3.7 V/dec, and turn-on voltage (Vto) of -3 V. As a result, the optimized a-IGZO TFT has improved electrical characteristics with oxygen vacancies having the highest conductivity.

Reversible Total Ionizing Dose Effects in NiO/Ga2O3 Heterojunction Rectifiers

NiO/Ga2O3 heterojunction rectifiers were exposed to 1Mrad fluences of Co-60 g-rays either with or without reverse biases. While there is small component of Compton electrons (600 keV), generated via the interaction of 1.17 and 1.33 MeV gamma-photons with the semiconductor, which in turn can lead to displacement damage, most of the energy is lost to ionization. The effect of the exposure to radiation is a 1000x reduction in forward current and 100x increase in reverse current in the rectifiers, which is independent of whether the devices were biased during this step. The on-off ratio is also reduced by almost 5 orders of magnitude. There is a slight reduction in carrier concentration in the Ga2O3 drift region, with an effective carrier removal rate of < 4 cm-1. The changes in electrical characteristics are reversible by application of short forward current pulses during repeated measurement of the current-voltage characteristics at room temperature. There are no permanent total ionizing dose effects present in the rectifiers to 1 Mad fluences, which along with their resistance to displacement damage effects indicate these devices may be well-suited to harsh terrestrial and space radiation applications if appropriate bias sequences are implemented to reverse the radiation-induced changes.

Solid-State Surface Patterning on Polymer Using the Microcellular Foaming Process

This study proposes a novel process that integrates the molding and patterning of solid-state polymers with the force generated from the volume expansion of the microcellular-foaming process (MCP) and the softening of solid-state polymers due to gas adsorption. The batch-foaming process, which is one of the MCPs, is a useful process that can cause thermal, acoustic, and electrical characteristic changes in polymer materials. However, its development is limited due to low productivity. A pattern was imprinted on the surface using a polymer gas mixture with a 3D-printed polymer mold. The process was controlled with changing weight gain by controlling saturation time. A scanning electron microscope (SEM) and confocal laser scanning microscopy were used to obtain the results. The maximum depth could be formed in the same manner as the mold geometry (sample depth: 208.7 μm; mold depth: 200 μm). Furthermore, the same pattern could be imprinted as a layer thickness of 3D printing (sample pattern gap and mold layer gap: 0.4 mm), and surface roughness was increased according to increase in the foaming ratio. This process can be used as a novel method to expand the limited applications of the batch-foaming process considering that MCPs can impart various high-value-added characteristics to polymers.

Study of GaN/AlGaN air structure gate HEMTs with high linearity for RF applications

The effect of a novel float gate HEMT with Gan cap under the gate is studied, its DC and RF characteristics have been shown by using SILVACO TCAD tool, as contrast, the simulation of the conventional T shape gate hemt, which fitting well with the experimental result, is also demonstrated. The proposed structure offers approximately 5 times improvement in power gain cutoff frequency (fmax) and current gain Cut-off frequency(fT) (from 5.68 and 3.7 GHz to 30.1 and 20.1 GHz, respectively.) and it greatly enhances the linearity of the Gan based HEMT, a much flatter curve for fT/fmax versus gate voltage are also shown, and 1 V positive threshold voltage shift is gained, meanwhile the off-state drain leakage current is also improved to a certain extend, therefor the hemt obtains a much higher Ion/Ioff ratio, without sacrificing the saturate current. Besides, the degradation of drain current due to the self-heating effect is also ameliorated by applying the novel structure. Finally, the corresponding electrical characteristic changes are systematically analyzed according to the energy band and other schematic diagrams, the physical insight is given in explaining the mechanism inside.

Reversible total ionizing dose effects in NiO/Ga2O3 heterojunction rectifiers

NiO/Ga2O3 heterojunction rectifiers were exposed to 1 Mrad fluences of Co-60 γ-rays either with or without reverse biases. While there is a small component of Compton electrons (600 keV), generated via the interaction of 1.17 and 1.33 MeV gamma photons with the semiconductor, which in turn can lead to displacement damage, most of the energy is lost to ionization. The effect of the exposure to radiation is a 1000× reduction in forward current and a 100× increase in reverse current in the rectifiers, which is independent of whether the devices were biased during this step. The on–off ratio is also reduced by almost five orders of magnitude. There is a slight reduction in carrier concentration in the Ga2O3 drift region, with an effective carrier removal rate of &amp;lt;4 cm−1. The changes in electrical characteristics are reversible by application of short forward current pulses during repeated measurement of the current–voltage characteristics at room temperature. There are no permanent total ionizing dose effects present in the rectifiers to 1 Mad fluences, which along with their resistance to displacement damage effects indicate that these devices may be well-suited to harsh terrestrial and space radiation applications if appropriate bias sequences are implemented to reverse the radiation-induced changes.

Analysis of Repetitive Bending on Flexible Wireless Power Transfer (WPT) PCB Coils for Flexible Wearable Devices

In this article, we first designed, measured, and analyzed flexible wireless power transfer (WPT) coils with repetitive bending cycles. To analyze any changes in electrical characteristics through repetitive bending cycles, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times3$ </tex-math></inline-formula> cm flexible printed circuit board (PCB) coils were fabricated using polyimide substrates. Different coil configurations are designed to find a mechanically robust, flexible PCB coil design. First, we analyzed single-layer and double-layer coils. Generally, via is the mechanically weakest part of the PCB, hence the diameter of the via varies to observe the effect of repetitive bending cycle. Ten thousand bending cycles with a bending radius of 3 mm and a bending cycle frequency of 1 Hz were used to analyze the electrical changes. Moreover, the bending position of the coil is varied to observe the bending effect. The flexible coil’s direct current (dc) resistance is measured during the bending cycle. After the repetitive bending test is completed, the coil impedance is analyzed in a frequency domain. As a result, we conclude that the flexible WPT coil is robust from mechanical stress when the layer of the coil is single a layer, the bending line is applied vertically, and the diameter of the via is small.

Micro LED Display Pixel Circuit Using Amorphous Indium-Gallium-Zinc Oxide Thin-Film Transistor

Micro LED (μ-LED) refers to a micro-light emitting diode with a chip size of 5 to 100 μm. Since micro-LED displays use individual LED chips as a light source of the pixel, they do not need backlight and color filters, which are suitable for implementing flexible displays. In addition, micro-led displays have many advantages over OLED displays, such as excellent color gamut, power consumption, lifetime, and response time. With these advantages, micro-LED displays are attracting attention as next-generation displays, and accordingly, interest in micro-LED driving technology is increasing. While existing OLED displays express grayscale by controlling the amount of current flowing through the light-emitting device, micro-LED can have a problem of color change depending on the grayscale because the light-emitting wavelength shifts when the amount of current changes. Therefore, in order to express a certain color, it is necessary to express the grayscale by adjusting the emission time at the same current density. That is, it is more suitable to use the PWM(pulse width modulation) for each pixel than to use the PAM(pulse amplitude modulation) for the grayscale representation of the OLED display. Therefore, unlike OLED, the micro-LED display requires a new pixel circuit because it must use a PWM driving. In addition, unlike LCDs, micro-led displays are sensitive to changes in electrical characteristics of TFTs depending on the location of each pixel or external stress. Thus, threshold voltage compensation is essential because changes and degradation of the characteristics of the thin film transistor backplane, such as threshold voltage shift, cause non uniform brighteness. Therefore, we propose a PWM compensation pixel circuit based on a-IGZO TFT that can be fabricated on a flexible substrate and has a lower process cost than LTPS and greater mobility than a-Si TFT.The operation of proposed pixel is divided into (1) reset 1, (2) PWM data compensation, (3) reset 2, (4) CCG (constant current generation)compensation, and (5) emission. The circuit is divided into a CCG unit that generates a constant current and a PWM unit that adjusts emission time by a ramping signal. Figure 1 (a) shows the output current simulation result according to PWM data voltage variation. When the PWM data voltages vary from -1 to ~ - 5V, the currents were constant at 70.9 μA, and the smaller the PWM data voltage, the longer the emission time was. In addition, Figure 1 (b) shows the effect of the threshold voltage compensation. The current and emission time are constant for various threshold voltages such as 1, 2, and 3 V. Figure 1

고전계 노화 SiC-MOSFET 소자를 가지는 양방향 DC-DC 컨버터 특성 분석 연구

Recently, the use of Silicon-carbide Metal Oxide Semiconductor (SiC-MOSFET) with high frequency and low loss characteristics is increasing in power conversion systems. SiC-MOSFET is aged due to the kinetic energy of electrons and thermal stress. In this case, the aged SiC-MOSFET may not perform as expected and may cause a failure of the power conversion system. This can lead to personal injury and property damage, so it is very important to increase reliability by identifying and analysing the aging process of SiC-MOSFET. In this paper, changes in electrical characteristics due to SiC-MOSFET aging and changes in loss and efficiency of the power conversion system are verified through experiments and simulations. A high electric field aging methodology are used to accelerate the SiC-MOSFET aging. Thereafter, a change in loss occurring during device aging are measured through a double pulse test, and this is modeled. By applying the loss modeling result to a bidirectional DC-DC converter, loss changes and efficiency changes due to converter aging are analyzed to determine the effect of the SiC-MOSFET aging on the converter.

Red, green and blue InGaN micro-LEDs for display application: temperature and current density effects.

Micro-LED has attracted tremendous attention as next-generation display, but InGaN red-green-blue (RGB) based high-efficiency micro-LEDs, especially red InGaN micro-LED, face significant challenges and the optoelectronic performance is inevitably affected by environmental factors such as varying temperature and operating current density. Here, we demonstrated the RGB InGaN micro-LEDs, and investigated the effects of temperature and current density for the InGaN RGB micro-LED display. We found that temperature increase can lead to the changes of electrical characteristics, the shifts in electroluminescence spectra, the increase of full width at half maximum and the decreases of light output power, external quantum efficiency, power efficiency, and ambient contrast ratios, while current density increase can also give rise to different changing trends of the varieties of parameters mentioned just above for the RGB micro-LED display, creating great challenges for its application in practical scenarios. Despite of the varying electrical and optical charateristics, relatively high and stable colour gamut of the RGB display can be maintained under changing temperature and current density. Based on the results above, mechanisms on the temperature and current density effects were analyzed in detail, which would be helpful to predict the parameters change of micro-LED display caused by temperature and current density, and provided guidance for improving the performance of InGaN micro-LED display in the future.

A highly sensitive Nano Gap Embedded AlGaN/GaN HEMT sensor for Anti-IRIS antibody detection

This study investigates the feasibility of Nano gap embedded AlGaN/GaN HEMT to sense antibody-antigen reaction. The sensor can detect the binding response of a typical antibody Ixodes ricinus immunosuppressor (anti-Iris) protein in Nano cavity. The sensor performance is analyzed by the change in electrical characteristics by the anti-iris antibody and iris antigen interaction. The device performance is optimized independently by varying cavity thickness, cavity length, biomolecule length, and Al composition. The output drain current recorded at VDS = 10V was linearly incremented with the length of the bio layers. The increase in cavity thickness and length will reduce the sensitivity due to a reduction in the cavity fill-in factor. The maximum sensitivity obtained is 169% at a cavity thickness of 10 nm and cavity length of 100 nm with 30% Al content. Silvaco Atlas simulation software has simulated and optimized the proposed device structure.

Electrophysical Properties of Monocrystalline n-Si+0.4at%Ge:P Alloy irradiated by 60Co Gamma Photons

In the monocrystal n-Si+0.4at.%Ge:P alloy irradiated with 60Co gamma photons non-monotonic changes in electrical resistance, current carrier concentration and mobility were detected by isochronal annealing at a temperature range of 20-400°C. The contribution of current transformations in the structure of radiation defects (PV, VO, VO2, CiCs, CiOi) to the temperature changes of electrical characteristics is analyzed. n-p conversion was detected at the critical temperature (~100°C) of isochronal annealing. Dissociation of PV centers and formation of electrically active VO centers were detected in the 120-150°C range. As a result, the concentration of current carriers increases. At elevated temperatures (&gt; 150°C) non-monotonic changes in electrical characteristics are observed.The paper analyzes the contribution of Ge to the anomalous temperature changes of the electrophysical characteristics of the n-SiGe alloy.

Optimization of Feedback FET with Asymmetric Source Drain Doping Profile.

A feedback field-effect transistor (FBFET) is a novel device that uses a positive feedback mechanism. FBFET has a high on-/off ratio and is expected to realize ideal switching characteristics through steep changes from off-state to on-state. In this paper, we propose and optimize FBFET devices with asymmetric source/drain doping concentrations. Additionally, we discuss the changes in electrical characteristics across various channel length and channel thickness conditions and compare them with those of FBFET with a symmetric source/drain. This shows that FBFET with an asymmetric source/drain has a higher on-/off ratio than FBFET with a symmetric source/drain.

Analysis of Cr/Au contact reliability in embedded poly-Si micro-heater for FET-type gas sensor

Gas sensors with micro-heaters are being widely studied in various fields. However, there are few systematic studies examining the effect of embedded heaters on their reliability and gas detection features. In this work, we investigate the change in electrical characteristics of the heater that occurs when thermal stress and current stress are applied to the embedded micro-heater for the FET-type gas sensor. Four different patterns of micro-heaters exhibited the same resistance change. Also, we investigate the effect of the increase in contact resistance between the poly-silicon heater and the metal (Cr/Au) electrodes on the gas sensing characteristics. As the heater resistance increases by 12%, the power consumption for optimal gas response increases by 58%, and the gas response is reduced by 46% without compensation of the heater voltage. The result indicates that the heating efficiency of the poly-silicon heater also changes during the degradation of the heater. The reason for the increase in the heater resistance and the change in the heating efficiency is explained by the inter-diffusion of Cr atoms to the surface through the Au layer. The diffusion of Cr atoms is confirmed by TEM and EDS analysis in the contacts at both ends of the heater. The results suggest that the temperature at the same voltage applied across the heater should also be considered in the reliability of the sensor platform.

Effects of the Sn4+ Substitution and the Sintering Additives on the Sintering Behavior and Electrical Properties of PLZT

(Pb, La)(Zr, Ti)O3 (PLZT) with antiferroelectric properties can be applied as a capacitor whose capacitance increases in a high electric field. From this, we obtained a high sintering density at 950 °C by adding low-temperature sintering additives, 8.0 wt% of PbO and 2.5 wt% of ZnO, simultaneously to a (Pb0.88, La0.12)(Zr0.86, Ti0.14)O3 composition. The change in electrical characteristics was confirmed in terms of Sn4+ substitution, resulting in no change in the sintering density by Sn4+ substitution. However, as the amount of Sn4+ substitution increases, the dielectric constant gradually decreases from 1300 to 700, and the grain size decreases from about 4 to 1 µm in terms of microstructure. In the crystal structure analysis, the general formation of a single perovskite structure was confirmed. The results of the hysteresis curve measurement revealed that the breakdown electric field increases from 4 to 9 kV·mm−1 as the amount of Sn4+ substitution gradually increases. However, polarization decreases in the same way as the permittivity trend. The composition exhibits excellent electrical properties when the ratio of Sn4+ is 0.4: a high energy storage density of 3.5 J·cm−3, energy efficiency of 80%, and breakdown electric field of about 8.5 kV·mm−1.