Current Voltage Research Articles

Optimization Method of SiC MOSFET Switching Trajectory Based on Variable Current Drive

Silicon carbide (SiC) MOSFETs exhibit superior performance compared to traditional silicon (Si) MOSFETs, characterized by faster switching speeds, lower on-resistance, higher breakdown voltage, and greater operational temperature tolerance. These attributes make SiC MOSFETs highly suitable for applications in electric vehicles, charging stations, and mobile devices. However, their rapid switching speed can intensify current and voltage overshoot and oscillations during device switching, leading to increased device losses or potential damage. To address this issue, this paper proposes a current-type active gate drive (AGD) circuit. The circuit first detects the rate of change in the drain current and drain-source voltage. Subsequently, it employs an analog amplifier circuit and adjustable drive resistors to decelerate the rate of change in the drain-source voltage and drain current. As a result, overshoot and oscillation in the drain-source voltage and drain current are mitigated. Experimental results demonstrate that the proposed AGD circuit can reduce drain current overshoot by 60%, drain-source voltage overshoot by 15.38%, and waveform oscillations. Additionally, the AGD circuit decreases conduction and turn-off losses by 24% and effectively mitigates electromagnetic interference (EMI) issues within the frequency range of 0.1 to 3 MHz.

Influence of annealing treatment on performance of 4H–SiC SBD irradiated by heavy ions under room temperature and low temperature

The influence of the annealing treatment on the performance of commercial 4H–SiC Schottky barrier diodes (SBDs) subjected to heavy ion irradiation under room temperature (RT) and low temperature (LT) are presented. Experimental results confirm that annealing treatment effectively eliminates defects and interface states caused by heavy ion irradiation, particularly for 4H–SiC SBD under LT irradiation. Increasing the annealing temperature leads to the slight improvement in forward current, leakage current and breakdown voltage. However, the annealing process may result in the formation of Ti and Si compounds at the interface between the Schottky metal and SiC, as well as a significant number of vacancies. Combined with Technology Computer Aided Design (TCAD) simulations, it is concluded that the interface trap charge concentrations exceeding 1 × 1012 cm−2 significantly impact the breakdown characteristics of 4H–SiC SBDs.

Design of a welding table as a medium for determining elbow points and joints

Welding is a method of joining two or more metals with electrode extension media using current heating and voltage according to the variation in the thickness of the iron material used. Welding is one of the connection media with a patent system, meaning that the results of the process can be changed by damaging the results of the welding process. From looking at several welding workshops, almost all of them to do welding are under or on the ground so many workers complain that they tend to be more tired and the welding results are less than optimal, especially for symmetrical or straightness of the connection results. The method used in this research is to design a welding table that is adjusted to the level of needs, especially for the height of the table and the centric axis to combine so that the results of the connection process are completely straight and reduce the results of welding defects. The purpose of designing this welding table is to use it as a method for working on the welding process so that the welding results are really strong and straight according to the design drawing. From the results of the design process, a welding table is obtained with iron material as a table base to place the workpiece to be cut. using borders of iron with a thickness of approximately 120 x 240 x 40cm using Material: Iron plate about 5-6 mm thick. In addition, the results of the design process also reduce the welding process time for blunt joints from 85 seconds to 48 seconds, overlap joints from 85 seconds to 60 seconds, and T joints from 88 seconds to 81 seconds. The quality of the welding results is visually better, the results of welding defects are smaller and straighter or symmetrical

Compact modeling of short-channel effects in back-gated 2D negative capacitance (NC) FETs

The negative capacitance field-effect transistor with 2D channel material (2D NC-FET) holds significant promise for low-power applications owing to its remarkable resilience against short-channel effects (SCEs) and favorable noise characteristics. In this study, we establish a compact current–voltage (I–V) model for short-channel back-gated 2D NC-FETs with metal-ferroelectric-metal–insulator–semiconductor structure by self-consistently solving the two-dimensional Poisson, drift–diffusion and Landau–Khalatnikov equations. The proposed model is valid and continuous throughout the entire operating regime, including the fully-depleted region, partly-depleted region, and accumulation region. Furthermore, we derive analytical equations for the threshold voltage ( VTH ) and subthreshold swing ( SS ) of back-gated 2D NC-FETs based on the developed I–V model. Lastly, we elucidate the influence mechanisms of various device parameters and voltage bias on the subthreshold characteristics of short-channel back-gated 2D NC-FETs using the proposed I–V model in conjunction with analytical expressions of VTH and SS . Our findings reveal that back-gated 2D NC-FETs shows unconventional degradation behavior in VTH and SS, resulting from the competition between traditional SCEs and novel negative capacitance effects.

Artificial optoelectronic synapses based on flexible and transparent oxide transistors

The development of artificial optoelectronic synapses utilizing flexible, and transparent oxide transistors is crucial for advancing neuromorphic computing and wearable electronics. Here, we propose artificial optoelectronic synapses on flexible and transparent devices based on an ion-gel gated oxide transistor. The device consists of indium-tin-oxide/ion-gel thin film conformity fabricated on a polyethylene terephthalate substrate. The device exhibited a loop opening in current–voltage properties, and its operating mechanism was ascribed to charge trapping and de-trapping. The neuromorphic behaviors can also be simulated by this device for instance, namely ultraviolet (UV) induced short-term memory, long-term memory, paired-pulse facilitation, and learning/forgetting behaviors. Additionally, electrical habituation and UV potentiation were executed. This work paves the way for the realization of low-cost flexible and transparent synaptic wearable electronics.

Self‐Selective Crossbar Synapse Array with n‐ZnO/p‐NiOx/n‐ZnO Structure for Neuromorphic Computing

AbstractArtificial synapse devices are essential elements for highly energy‐efficient neuromorphic computing. They are implemented as crossbar array architecture, where highly selective synaptic weight updates for training and sneak leakage‐free inference operations are required. In this study, self‐selective bipolar artificial synapse device is proposed with n‐ZnO/p‐NiOx/n‐ZnO heterojunction, and its analog synapse operation with high selectivity is demonstrated in 32 × 32 crossbar array architecture without the aid of selector devices. The built‐in potential barrier at p‐NiOx/n‐ZnO junction and the Zener tunneling effect provided nonlinear current–voltage characteristics at both voltage polarities for self‐selecting function for synaptic potentiation and depression operations. Voltage‐driven redistribution of oxygen ions inside n–p–n oxide structure, evidenced by x‐ray photoelectron spectroscopy, modulated the distribution of oxygen vacancies in the layers and consequent conductance in an analog manner for the synaptic weight update operation. It demonstrates that the proposed n–p–n oxide device is a promising artificial synapse device implementing self‐selectivity and analog synaptic weight update in a crossbar array architecture for neuromorphic computing.

Deformation theory and nonlinear dynamic behavior of PVC gel actuators

Polyvinyl chloride (PVC) gel generates complex nonlinear vibration behavior under an alternating current voltage excitation, which has potential application as a dynamic electromechanical actuator. However, there are few studies on the deformation theory of PVC gel actuators, especially the dynamic nonlinear response theory. In this paper, a complex dynamic model is established according to the electrodeformation mechanism of PVC film, and the nonlinear dynamic behavior of the actuator is numerically studied by a differential equation. The effects of applied voltage amplitude, voltage frequency, dibutyl adipate content, mechanical tension, and bias voltage on the dynamic properties of PVC film were analyzed under the condition of equal biaxial tension. The variation of amplitude and the generation and disappearance of the beat frequency during vibration are analyzed by using time-domain characteristics. The degree of PVC actuator nonlinearity as well as vibration stability and periodicity is also reflected based on the phase path and Poincare map. Finally, the law of influence of external condition parameters on the dynamic response of the PVC actuator is obtained.

Frequency reconfigurable slot antenna utilizing solid-state plasma S-PIN diodes: simulation and experimental analysis

This article examines the feasibility of integrating solid-state plasma surface p-i-n (S-PIN) diodes into on-chip slots using silicon-on-insulator technology. Two categories of solid-state plasma S-PIN diodes are characterized. Simulations analyze the current–voltage (I–V) characteristics, carrier concentrations, potential distribution, and thermal considerations of both single and dual S-PIN diodes, with optimization of their structural parameters and sizes. Experimental tests on fabricated S-PIN diodes of varying sizes with bias lines embedded in the on-chip slots show favorable I–V characteristics for both types of diodes. The measured results closely align with simulation predictions for the diodes’ conduction onset voltages. Additionally, a cavity-backed slot antenna is proposed to evaluate and compare radiation characteristics resulting from integrating different types of S-PIN diodes.

Effect of hydrogen treatment on 4H-SiC Schottky barrier diodes

In this letter, 4H-SiC Schottky barrier diodes (SBDs) with Ti Schottky metal have been subjected to hydrogen treatment in a confined environment of 4% H2 and 96% N2 at 150 °C. The effect of hydrogen treatment on the SBDs electrical characteristics has been investigated by technical computer-aided design simulation (TCAD) and power device analyzer curve tracer. The change of electrical parameters of SBDs measured after hydrogen treatment is studied in detail, and the related degradation mechanism is discussed. It was found that hydrogen treatment affected both the interface region and bulk region of SiC SBDs. After hydrogen treatment, the Schottky barrier increases slightly, the ideal factor (n) decreases slightly, and the interfacial state density (D it) decreases. Hydrogen treatment resulted in a slight reduction in specific on-resistance (R on-sp), which was attributed to the diffusion of H in SBDs. Through TCAD simulation, it is determined that the diffusion of H in the body diode of SBDs is the main reason for the degradation of high forward current and high reverse voltage characteristics.

Enhanced performance of quasi-solid-state silicon-air batteries through light-assisted anodic reactions

Silicon-air batteries (SABs) offer a promising energy storage solution due to their high theoretical energy density, cost-effectiveness, and environmental friendliness. However, practical applications are hindered by limitations in maximum discharge current density and discharge voltage, stemming from intrinsic electrochemical properties of the silicon (Si) anode and surface oxidation kinetics. This study addressed the low maximum discharge current density of SABs by leveraging the Si semiconductor properties and employing a light-assisted strategy. Introducing light to the silicon anode generates photogenerated electron-hole pairs. Furthermore, introducing light to the Si anode allowed for the generation of photogenerated electron-hole pairs. The resulting holes reacted with OH- ions to form hydroxyl radical (OH), which efficiently oxidized the Si surface, thereby facilitating electrochemical reactions. This enhancement increased the anodic reaction kinetics, thereby enhancing the maximum discharge current density of SABs. Furthermore, through this strategy, light-assisted SABs exhibited significant performance improvements: under 1 sun illumination, maximum discharge current density increased by 50.0 %, discharge voltage by 10.0 %, and power density by 45.0 %. Under 3 suns illuminations, these metrics improved further, with maximum discharge current density increasing by 87.5 %, discharge voltage by 20 %, and power density by 200 %. Additionally, quasi-solid-state SABs (QSSSABs) according to this strategy exhibited versatility across various application scenarios, thereby significantly expanding the practical potential of SABs technology.

Studies on suppressed surface recombination of InGaN-based red light-emitting diodes with V-pits

InGaN-based red light-emitting diodes (LEDs) are a promising candidate to achieve high efficiency, which is highly desired by the display market. Understanding their size-dependent properties is crucial for further performance improvement. In this work, different sized InGaN red LEDs (from 500 × 500 to 15 × 15 µm2) based on V-pits were characterized systematically. The current–voltage characteristics show that the leakage current density, revealed either in forward or reverse bias, is independent of the chip size. Further light output power measurements and current dependent electroluminescence also reveal very weak dependence of the power density on chip size showing insensitivity the chip perimeter. The suppressed surface recombination effect may be due to effective carrier trapping effect by the V-pits, which prevents the carriers from flowing to the sidewalls. By detailed analysis of the spatially resolved electroluminescence, an anti-correlation between the emission wavelengths and the intensities was observed, with the longer wavelength emitting regions exhibit weaker intensity, which can be explained by the reduced carrier density in the V-pit-rich regions as carriers are partially captured by quantum wells associated with the V-pits and the associated dislocations. This study will pave the way for further understanding and improving the efficiency of InGaN red LEDs including micro-LEDs.

An Ultra-Low-Voltage Approach to Accurately Set the Quiescent Current of Digital Standard Cells Used for Analog Design and Its Application on an Inverter-Based Operational Transconductance Amplifier

An approach to design analog building blocks based on digital standard cells is presented in this work. By ensuring that every CMOS inverter from a standard-cell library operates with a well-defined quiescent current and output voltage, the suggested method makes it possible to construct analog circuits that are resistant against PVT variations. The method uses the local supply voltages connected to the source terminals of the p-channel and n-channel MOS transistors of the standard-cell inverters as control inputs. It is based on adaptive supply voltage generator (ASVG) reusable blocks, which are comparable to those used in digital applications to handle process variations. All of the standard-cell inverters used for analog functions receive the local supply voltages produced by the ASVGs, which enable setting each cell’s quiescent current to a multiple of a reference current and each cell’s static output voltage to an appropriate reference voltage. Both the complete custom design of the ASVG blocks and a theoretical study of the feedback loop of the ASVG are presented. An application example through the design of a fully synthesizable two-stage operational transconductance amplifier (OTA) is also provided. The TSMC 180 nm CMOS technology has been used to implement both the OTA and the ASV generators. Simulation results have demonstrated that the proposed approach allows to accurately set the quiescent current of standard-cell inverters, dramatically reducing the effect of PVT variations on the pmain performance parameters of the standard-cell-based two-stage OTA.

Three-Coil Wireless Charging System Based on S-PS Topology

To protect the battery, radio energy transmission charging typically uses constant current (CC) charging before switching to constant voltage (CV) charging to enhance battery durability. This paper proposes adding an auxiliary clamp coil to the original circuit topology. The IPT battery charger designed with the auxiliary clamp coil can achieve both constant current (CC) and constant voltage (CV) outputs. The mutual inductance between the auxiliary clamp coil and the primary side coil greatly influences the output performance of the entire IPT system, so the auxiliary clamp coil should not be too large. To solve this problem, an S-S-PS circuit with secondary compensation topology in the secondary coil is proposed. This circuit topology reduces the size of the auxiliary clamp coil, allowing it to be placed in an optimal position. When the constant voltage output critical position is reached, the IPT system can still automatically, continuously, and smoothly switch between CC and CV modes. Consequently, this approach avoids increased cost consumption associated with detecting CC-CV switching thresholds, adding wireless transmission communication modules, real-time control of the power transmitter, and active protection of the circuit during constant current charging. Finally, a 48 V/2.5 A prototype was built to verify that the IPT system has CC-CV conversion functionality.

Optimum Solar Cell Power Conversion Efficiency-Based Patterned Planar Solar Surface Morphology with Various Solar Cell Absorber Structures

This paper simulated the optimum solar cell power conversion efficiency-based planar solar surface morphology with various solar cell absorber structures. The spectral light intensity, reflected, absorbed, and transmission coefficients versus wavelength band spectrum varied from 300[Formula: see text]nm to 1300[Formula: see text]nm through the visible to near-infrared regions. The optimum solar cell performance parameters or key parameters are studied with different solar cell structure designs based on different surface contact and back contact layers. Cumulative generation current, cumulative electron–hole pair generation rate and electron–hole pair generation rate are clarified versus substrate depth for various solar cell structure designs. The absorbed current in substrate is optimized for various solar cell structure designs. Maximum power voltage and current are also optimized for the proposed solar cell structure design. The effective solar cell power efficiency is also demonstrated based on the optimized maximum power current and maximum power voltage.

Investigation of numerical transport models in protein-based molecular junctions with cofactors of diverse chemical natures

The cofactors of proteins dictate the charge transport mechanism across molecular junctions when self-assembled protein monolayers are sandwiched between two metal electrodes. Here, we summarized how the chemical coordination nature of cofactors in various proteins modulates electrical conductance by investigating electronic transport studies across different protein-based molecular junctions under various forces applied under the AFM tip. We have utilized several numerical techniques of electronic transport to analyse the experimentally obtained current–voltage measurements across various protein-based molecular junctions and depicted the origin of electronic modulation in the electrical conductance under different external stimuli. We could also find the origin of electronic conductance modulation under external stimuli at various applied forces by obtaining several analytical transport parameters such as energy barrier, coupling strength, and electrical conductance values. Utilizing density-functional-theory calculations, we further validate that the electronic density of states present in the cofactors within the proteins dominates the electronic transport behaviours across protein-based molecular junctions. Our findings reveal the limiting factor for applying various external stimuli on different proteins, which could be further valuable in bioelectronic applications. We have also found that the organic cofactor containing protein follows all the tunneling mechanism-related numerical transport models and the electronic transport across proteins with pure inorganic cofactors follows Landauer transport formalism.

Lead Complexes of 3‐(2‐pyridyl)‐5‐(4‐methoxyphenyl)‐1,2,4‐Triazine: Synthesis, Characterization and Application in Organic Light‐Emitting Diodes (OLEDs)

AbstractThree new Pb(II) complexes of 3‐(2‐pyridyl)‐5‐(4‐methoxyphenyl)‐1,2,4‐triazine (PMPT) ligand with different anionic co‐ligands (1: nitrate, 2: perchlorate and 3: isothiocyanate) in 2 : 1 molar ratios of PMPT ligands and lead(II) salts, [Pb(PMPT)2(NO3)2] (1), [Pb(PMPT)2(ClO4)2] (2) and [Pb(PMPT)2(NCS)2] (3) were synthesized and characterized by physicochemical (CHN, FT‐IR and 1H NMR) and single‐crystal X‐ray diffraction methods. By considering the obtained structural parameters, the lead atoms in 1, 2 and 3 have PbN4O4, PbN4O2 and PbN6 environments, respectively, with holodirected (for 1) and hemidirected (for 2 and 3) coordination spheres. We used electro‐optical Pb(II) complexes family as emitting layer to investigate in fabrication of OLEDs. The current–voltage, luminescence‐voltage characteristics and the absorption (Abs) and electroluminescence (EL) properties of the complex have been investigated. The forester radius, quantum yield, and electroluminescence have been studied.

Synthesis of ZnO/CZTS Hetero-Structure Junction by Sol–Gel Spin Coating Technique

Pertaining to the optimal band alignment of ZnO and CZTS, the heterostructure was fabricated with CZTS as the absorber layer and ZnO being the buffer layer coated on the FTO glass for photovoltaic application. Both the layers were deposited by using sol–gel spin coating technique. The results revealed the polycrystalline nature of both ZnO and CZTS films with distinct phase formations, with ZnO exhibiting prominent diffraction peaks at 31.77, 34.31, 36.20, 47.47, and 56.59° corresponding to (100), (002), (101), (102), and (110) planes, while CZTS showed diffraction peaks at (112), (220), and (312) planes. ZnO thin films demonstrated high optical transmittance (∼90%) and exhibited a wide band gap of 3.24 eV, while CZTS demonstrated a band gap of 1.44 eV. AFM images showed smooth surfaces with favorable topography for both films. Hall effect measurements indicated differences in electrical properties of the two films. Raman spectroscopy revealed vibrational energy patterns in both films. Additionally, current–voltage (I-V) characteristics revealed the electrical behavior of the ZnO/CZTS heterojunction, shedding light on its diode characteristics under both dark and illuminated conditions. With CZTS’s ideal band gap of 1.44 eV, sunlight is easily absorbed, and ZnO’s high electron mobility makes it an effective layer for electron transport. As a result, power conversion efficiency can be improved.

Smart grid data compression and reconstruction by wavelet packet transform

A smart grid is a power network from generation to consumers and provides beneficial, steady, and safe electricity. It utilizes smart meters for billing, phasor measurement units to check the system's health., etc. As a result, it contains enormous volumes of real-time data that may be shared and stored by users, control centers, and services in a smart grid. It weakens the smart grid's communication networks. The size of the data in a smart grid will grow extremely in the future. As a result, it must reduce distortion in data compression and denoise while minimizing the demand on storage and communication networks. The goal of data compression and denoising should be to maximally conserve the useful data while accurately reflecting the state of the system and providing sufficient data regeneration at the receiving end. This paper has used lower-order different wavelets to represent a design to compress and reconstruct data at level three using wavelet Packet Transform. It works on the phasor measurement unit's current magnitude and voltage sag signals.•The proposed design has a better compression ratio.•Low reconstruction error.•This design is easy to access, systematic, profitable, and not time-consuming.

A physics based model for negative capacitance TFET considering variation in ferroelectric parameters

Here, an explicit analytical model of electrical properties like channel potential, electric field, drain current, and threshold voltage for a negative capacitance DGTFET structure is developed. The model properly calculates the channel potential profile by solving the Poisson equation using the Landau-Khalatnikov (LK) model (for incorporating the NC effect). The electric field expression is developed using a channel potential model. The drain current expression is obtained by mathematically integrating the rate of band-to-band tunneling generation over the channel thickness. The threshold voltage has been derived using a method called maximal trans-conductance. Furthermore, by varying the FE parameters like thickness (t fe ), coercive field (E C ), and residual polarization (P R ), we improve capacitance matching and gate control of the device. All of the model results demonstrated a perfect alignment with those discovered by TCAD simulations. Designing devices and circuits for low-power applications can be more effective from these results.

Synthesis of low-k SiONC thin films by plasma-assisted molecular layer deposition with tetraisocyanatesilane and phloroglucinol

Low-k SiONC thin films with excellent thermal stabilities were deposited using plasma-assisted molecular layer deposition (PA-MLD) with a tetraisocyanatesilane (Si(NCO)4) precursor, N2 plasma, and phloroglucinol (C6H3(OH)3). By adjusting the order of the N2 plasma exposure steps within the PA-MLD process, we successfully developed a deposition technique that allows accurate control of thickness at the Ångström level via self-limiting reactions. The thicknesses of the thin films were measured through spectroscopic ellipsometry (SE). By tuning the N2 plasma power, we facilitated the formation of –NH2 sites for phloroglucinol adsorption, achieving a growth per cycle of 0.18 Å cycle−1 with 300 W of N2 plasma power. Consequently, the thickness of the films increased linearly with each additional cycle. Moreover, the organic linkers within the film formed stable bonds through surface reactions, resulting in a negligible decrease in thickness of approximately −11% even upon exposure to a high annealing temperature of 600 °C. This observation was confirmed by SE, distinguishing the as-prepared film from previously reported low-k films that fail to maintain their thickness under similar conditions. X-ray photoelectron spectroscopy (XPS) and current–voltage (I–V) and capacitance–voltage (C–V) measurement were conducted to evaluate the composition, insulating properties, and dielectric constant according to the deposition and annealing conditions. XPS results revealed that as the plasma power increased from 200 to 300 W, the C/Si ratio increased from 0.37 to 0.67, decreasing the dielectric constant from 3.46 to 3.12. Furthermore, there was no significant difference in the composition before and after annealing, and the hysteresis decreased from 0.58 to 0.19 V owing to defect healing, while maintaining the leakage current density, breakdown field, and dielectric constant. The low dielectric constant, accurate thickness control, and excellent thermal stability of this MLD SiONC thin film enable its application as an interlayer dielectric in back-end-of-line process.