Diode Series Research Articles

A Scalable, Wide-Angle Metasurface Array for Electromagnetic Energy Harvesting.

A metasurface array for electromagnetic (EM) energy harvesting for Wi-Fi bands is presented in this paper; the metasurface array consists of a metasurface unit, a rectifier, and a load resistor. Each row of unit cells in the array is interconnected to form an energy transfer channel, which enables the transfer and concentration of incident power. Furthermore, at the terminal of the channel, a single series diode rectifier circuit and a load resistor are integrated in a coplanar manner. It is used to rectify the energy in Wi-Fi bands and enables DC energy harvesting across the load. Finally, a 5 × 7 prototype of the metasurface array is fabricated and measured for the verification of the rationality of the design. Testing in an anechoic chamber shows that the prototype achieves a 72% RF-DC efficiency at 5.9 GHz when the available incident power is about 7 dBm.

Enhanced Method for Estimating Unknown Parameters in Single Diode Model for Solar Photovoltaic Cells

Three models of equivalent circuit are frequently applied for modelling solar cells/modules: single, double and three diode models. Among these, the single diode (SD) model is currently the most widely applied for solar cell modelling. This model is characterized by five parameters, which can be estimated using various methods. In the present work, the unknown parameters of this model are determined using an improved hybrid method. Our research introduces an innovative approach for this purpose. Our method formulates and resolves the equations defining these critical parameters. Particularly, our main objective revolves around estimating the diode's saturation current (I0), series resistance, photocurrent (Iph) and parallel resistance (Rsh), ideality factor ( through these equations. We confirmed our method reliability by thoroughly simulating the I-V curves of six PV cells, showing the credibility and the precision of our approach. This research significantly advances solar cell modelling by offering an improved technique for estimating crucial parameters within the SD model, enhancing the accuracy and reliability of solar cell performance predictions.

Functional performance of low-cost electronic yarn for E-textiles

The current work presents and discusses the design and performance qualities of braided electronic yarns for woven textiles to produce red light-intensity effects. The design process involves a simple encapsulation process with adhesive tape and a heat-shrinkable tube to secure stainless-steel conductive threads (SS-CTs) to the solder pads of light-emitting diodes. These are arranged in a series against two SS-CTs to provide single positive and negative terminals at both ends. Findings from the infrared images show that the heat distribution and dissipation of the stainless-steel conductive threads are insignificant in affecting the wear comfort of the electronic textiles on the human body. The washing test shows the robust nature of the braided electronic yarns even after 20 cycles of being subjected to high agitation and mechanical stress. A proof of concept illustrates the effectiveness of the study results, which calls on further research work to enhance the durability and flexibility of the braided electronic yarns and electronic textiles to ensure a higher level of wear comfort. These braided electronic yarns would find end applications for nighttime visibility of pedestrians, a situation that would improve the recognition of drivers for reduced collision.Graphical abstractA simple low-cost process to manufacture electronic yarns (e-yarns) starts by embedding light-emitting diodes (LEDs) in series on two stainless-steel conductive threads (SS-CTs) through encapsulation in a heat-shrinkable tube (HST), and insulating one side of the SS-CT, then braided by using 8-core retroreflective threads that are then woven to form an electronic textile (e-textile). The braided e-yarns and e-textiles when washed exhibit good performance properties for clothing that would be interactive to enhance the nighttime visibility of pedestrians.Impact statementElectronic textiles otherwise known as e-textiles have been the subject of scholarly attention in recent years due to their performance properties and wide areas of application for entertainment, monitoring, and safety purposes. The use of appropriate electronic yarns (e-yarns) plays a key role in connectivity and provides the necessary feedback when applied to a textile material. E-yarns are now replacing a few modern electronic textiles (e-textiles) that use rigid copper wires commonly applied in electronic circuits for e-textiles and improve the wear comfort of the garment. The integration of light-emitting diodes (LEDs) into conductive threads to form electronic yarns for textile material can be applied not only for entertainment purposes but also as a safety feature for pedestrians. The use of appropriate components is necessary to ensure and maintain the textile quality and properties for effective wearability. Herein, an e-yarn fabricated with stainless-steel conductive threads and LEDs for e-textiles is presented. As part of ongoing research work to develop smart interactive clothing to increase the nighttime visibility of pedestrians, this work discusses the design and performance qualities of braided e-yarns for woven textiles. The success of these low-cost, flexible, and strong (high wash durability) braided e-yarns facilitates their integration into woven fabrics for smart clothing to enhance the visibility and therefore safety of pedestrians.

Electroconductive and photoelectric properties of Pt/(100) β-Ga2O3 Schottky barrier diode based on Czochralski grown crystal

Pt/(100) β-Ga2O3 Schottky barrier diodes were fabricated using a plate cleaved from the crystal grown by Czochralski method. Their electroconductive and photoelectric characteristics were studied. The following values were obtained: the Schottky barrier height (1.69/1.62/1.74 eV), ideality coefficient (1.09/1.14), saturation current density (9.91 × 10–15 A/cm2), diode series resistance (7.98 kΩ), and net donor concentration [(1.8–2.4) × 1018 cm–3]. The diodes demonstrate a high rectification ratio of 1010 at an applied voltage of ± 1 V and a relatively low experimental value of the leakage current density ∼10–11 A/cm2. These structures are solar-blind and also capable of operating in self-powered mode. The diodes are highly sensitive to short-wave ultraviolet radiation with a wavelength λ ≤ 265 nm. The maximum values of responsivity (20.4 A/W), external quantum efficiency (1.2 × 104%), and detectivity (9.6 × 1015 Hz0.5 × cm × W–1) of diodes were registered under exposure to irradiation at λ = 210 nm and at applied voltage of −1 V. The responsivity and external quantum efficiency values in the self-powered operation mode were 12.3 A/W and 7.2 × 103%, respectively. The diodes showed low rise and decay times in self-powered operation mode for photodiode based on Ga2O3: 14 and 30 ms, respectively.

Effects of Adding the Antiparallel Diodes in a Model of Solar Photovoltaic Cell: Theory and Pspice Simulations

Background: The photovoltaic (PV) array consisting of modules is considered as the fundamental electrical power conversion unit of the PV generator system. The PV array has nonlinear characteristics with the current-voltage (I-V) characteristic in the exponential form introduced by diodes. In this context, the key objective of the research carried out in the present study is to propose a novel PV cell, with anti-parallel diodes introduced in the circuit model in place of the single diode. Objective: The objective of this research is to compare the effects, magnitudes of current and power generated by the PV cell, with antiparallel diodes to those with single diodes. Methods: The model circuit containing two antiparallel diodes is first designed, and then analyzed through the circuit Equationuations found using the Kirchhoff’s laws. The I-V characteristics are modified in the hyperbolic sine form, and the model Equationuation is solved analytically and numerically using the MATLAB software. The analytical and numerical investigations are then confirmed by Pspice simulation, which is made possible with the introduction of additional bloc necessary to make the output signal voltage tunable in the opened circuit. Results: The I-V characteristic is plotted showing that when the voltage is lower than a particular, the model containing the antiparallel diode has the increasing of current, while that with single diode has constant current. Additionally the current generated by the PV cell oscillates increasingly when the supplied signal voltage is negative. We also found that the maximum power increases with the temperature. The expression of the cutoff signal voltage leading to zero current was also found and plotted, the increasing function of the number Ns of series diodes. As application, the PV circuit designed is used in the charging of the battery of electrical vehicle. Conclusion: The PV cell with antiparallel diodes generates currents for large band of signal voltage, and the power generated increases with temperature.

A Pulse Width Modulation Based Sliding Mode Controller for Phase-Shifted Full-Bridge Converter with Diodes in Series on the Lagging Leg

A Pulse Width Modulation Based Sliding Mode Controller for Phase-Shifted Full-Bridge Converter with Diodes in Series on the Lagging Leg

Power Injection and Free Resonance Decoupled Wireless Power Transfer System with Double-Switch

This article presents a type of power injection and free resonance decoupled wireless power transfer (WPT) system, the double-switch independent power injection and free resonance wireless power transfer (IPIFR-WPT) system working in CCM. Based on the stroboscopic mapping model, the theoretical results show that the operation point of the proposed WPT system is determined by itself instead of the switching control strategy. Specifically, once the voltage on the primary capacitance does not decrease to the input voltage in the free-resonance process, the diode in series would not turn on and the system would not switch to the power injection process. Therefore, there is a wide soft-switching margin to ensure the system operating in soft-switching states. Another characteristic of the proposed WPT system is the monotonicity between output power and operation cycle, which presents a simple power control method. And since the soft-switching margin may have intersection under dynamic coupling coefficient, the proposed system maintains soft-switching states with a fixed switching strategy and presents advantage to resist the dynamic change of coupling coefficient. All the characteristics of the proposed WPT system mentioned above have been verified in both theory and experiment.

Titania Nanoparticle-Stimulated Ultralow Frequency Detection and High-Pass Filter Behavior of a Flexible Piezoelectric Nanogenerator: A Self-Sustaining Energy Harvester for Active Motion Tracking.

A significant driving force for the fabrication of IoT-compatible smart health gear integrated with multifunctional sensors is the growing trend in fitness and the overall wellness of the human body. In this work, we present an autonomous motion and activity-sensing device based on the efficacious nucleation of the polar β-phase in an electroactive polymer. Representatively, we investigate the nucleating effect of TiO2 nanoparticles on weight-modulated PVDF-HFP films (PT-5, PT-10, and PT-15) and subsequently prototype a sensing device with the film that demonstrates superior β-phase nucleation. The PT-10 film, with an optimal polar β-phase, shows the highest remnant polarization (2Pr) and energy density of 0.36 μC/cm2 and 22.3 mJ/cm3, respectively, at 60 kV/cm. The films mimic a high pass filter at frequencies above 10 KHz with very low impedance and high ac conductivity values. The frequency-dependent impedance studies reveal an effective interfacial polarization between TiO2 nanoparticles and PVDF-HFP, explicitly observed in the low-frequency region. Consequently, the sensor fabricated with PT-10 as the sensing layer exhibits ultralow frequency detection (25 Hz) resulting from the blood flow muscle oxygenation. The device successfully senses voluntary joint movements of the human body and actively tracks a range of motions, from brisk walking to running. Additionally, through repetitive human finger-tapping motion, the nanogenerator lights up multiple light-emitting diodes in series and charges capacitors of varying magnitudes under 50 s. The real-time human motion sensing and movement tracking modalities of the sensor hold promise in the arena of smart wearables, sports biomechanics, and contact-based medical devices.

Solar Power Prediction Modeling Based on Artificial Neural Networks under Partial Shading

Photovoltaic systems are emerging as an important device to address the environmental pollution generated from conventional energy production. The objectives of this study are to accurately predict the power of photovoltaic systems under partial shading conditions and to model high-efficiency photovoltaic systems. First, the power loss under partial shading conditions was addressed using a bypass diode. In previous studies, for the power prediction, one or two parameters were trained through artificial neural networks. In this study, we employ five main parameters to improve the accuracy: the photo-current (Iph), diode saturation current (I0 ), diode idealization factor (n), series resistance (Rs), and shunt resistance (Rsh). Compared to the results of previous studies, the proposed model yielded consistent results. As a result, more accurate power predictions are possible with variations in temperature and irradiation.

Fabrication of n-ZnS/p-SnS, n-ZnO/p-SnS, and n-SnO2/p-SnS heterojunctions by 2-step SILAR process for photodetector applications

In this work, we present the fabrication and detailed analysis of three functional heterojunctions based on SnS. Unlike most of the previous reports, all semiconductor layers in the heterojunctions were deposited using the low-cost SILAR technique. The ZnS, ZnO, and SnO2 films, each with a thickness of 400 nm, were grown on a previously deposited 800 nm SnS layer, forming n-ZnS/p-SnS, n-ZnO/p-SnS, and n-SnO2/p-SnS heterojunctions. Current-voltage characteristics confirmed the successful formation of p-n junctions. Various models were used to estimate junction parameters such as diode ideality factor, barrier height, and series resistance. The fabricated diodes exhibited a prominent photo response under illumination. Photodetection figures of merit were estimated for all the devices. n-ZnS/p-SnS showed 0.003μA response current, with 0.27 sensitivity. The responsivity observed was around 0.6 μA /W with LDR of 2.09 dB. The specific detectivity was 106 Jones. Similarly, n-ZnO/p-SnS showed 0.021μA response current, with 0.38 sensitivity. The responsivity observed was around 4.2 μA /W with LDR of 2.80 dB. The specific detectivity was 106 Jones. However, n-SnO2/p-SnS showed remarkable figures of merit such as 2.4 μA response current, with 8.40 sensitivity. The responsivity observed was around 488 μA/W with LDR of 19.47 dB. The specific detectivity was 109 Jones. The rise and decay time of the photocurrent were 5 and 7 s, respectively.

Ultra-low turn-on voltage quasi-vertical GaN Schottky barrier diode with homogeneous barrier height

Quasi-vertical Schottky Barrier Diodes (SBDs) with near to ideal turn-on voltage and ideality factor (n) of 1.02, were fabricated on a GaN on Si substrate. The average turn-on voltage and on-resistance values were found to be 0.23 ± 0.005 V (at 1 A/cm2) and 1.76 ± 0.11 mΩcm2, respectively with diode series resistance of 11 Ω. The analysis of the current–voltage curve revealed a temperature-independent barrier height, however the capacitance–voltage method showed a negative temperature coefficient. This discrepancy is discussed in the paper. Variable range hopping through dislocations is shown to be the dominant reverse current leakage mechanisms identified in the fabricated diode, with a characteristic temperature, T0 of 2 × 1010 K.

An adaptive energy acquisition power supply for power transmission line

Reliable power supply is of great significance to the stable operation of the online monitoring device. This paper studies a kind of electric energy collection power supply based on the principle of current mutual inductance. The iron core is made of nanocrystalline alloy with high permeability, and the relationship between the number of turns and the energy consumption power is analyzed by equivalent circuit. A discharge circuit is formed by connecting multiple diodes in series to avoid oversaturation of the iron core, and the residual voltage on the diode supplies the load electric energy. Combined with simulation and experiment, the number of turns and the number of diodes in series are optimized, so that the power supply has high efficiency and is not easy to be deeply saturated. The rectifier bridge and DC-DC voltage regulator module are used to stabilize the output voltage. The test shows that the power supply can support reliable energy extraction within the range of wire current of 17A at least and 1000A at most, and can be applied to lines of various voltage levels.

Five parameters extraction of single diode PV model by metaheuristic optimization method by identified built-up data

Precision calculation of unknown photovoltaic (PV) modules or single diode models for PV cell specifications under various environmental conditions is needed to build a sunlight-based PV framework. Installing a PV system requires knowledge of all parameters, modeling, and optimization techniques because PV system analysis and configuration help generate renewable energy. This concept requires accurate modeling and calculation of identified and unknown parameters. The single-diode model is simple and accurate for different mathematical equations. Streamlining calculations requires distinguishing this nonlinear model. The current investigation calculated five unknown parameters and compared them with particle swarm optimization (PSO) and wind-driven optimization (WDO) optimization results. The said approach utilizes MATLAB software, analytical as well as optimization methods, and manufacturing data. The suggested method is simple, fast, and accurate for calculating diode ideality factor (A), output currents (Io), series resistance (Rs), Shunt resistance (Rsh), and photocurrent (Iph).

Evaluation of Polylactic Acid Polymer as a Substrate in Rectenna for Ambient Radiofrequency Energy Harvesting

This work details the design and experimental characterization of a 2D rectenna for scavenging radio frequency energy at 2.45 GHz (WiFi band), fabricated on polylactic acid polymer (PLA) using a plastronics approach. PLA is the RF substrate of both antenna and rectifier. The two transmission line (TTL) approach is used to characterize the substrate properties to be considered during design. A linearly polarized patch antenna with microstrip transmission feeding is connected to a single series diode rectifier through a T-matching network. The antenna has simulated and measured gain of 7.6 dB and 7.5 dB, respectively. The rectifier has a measured DC output power of 0.96 μW at an optimal load of 2 kΩ under RF input power of −20 dBm at 2.45 GHz. The power conversion efficiency is 9.6% in the latter conditions for a 54 × 36 mm patch antenna of a 1.5 mm thick PLA substrate obtained from additive manufacturing. The power conversion efficiency reaches a value of 28.75% when the input power is −10 dBm at 2.45 GHz. This corresponds to a peak DC power of 28.75 μW when the optimal load is 1.5 kΩ. The results compare significantly with the ones of a similar rectenna circuit manufactured on preferred RF substrate.

Batch Furnace Chemical Vapor Deposition of Pure Boron Layers on Si and GaN Substrates for Low-Leakage-Current Diode Fabrication

Boron deposition on both n-Si and n-GaN in the temperature range 250 - 500 °C, has been shown to form diodes with low saturation currents, i.e., electron injection from the n-substrate into the B-layer was efficiently suppressed. Moreover, down to 3-nm-thick B-layers on Si were shown to form a material barrier to Al, opening the possibility of fabricating Au-free gates for gallium-nitride high-electron-mobility transistors (GaN HEMTs). Several different chemical- and physical-vapor deposition (CVD/PVD) methods for depositing B have been studied for fabricating p+n-like Si diodes, called PureB diodes, all with comparable results. In this paper, the deposition of B-layers from diborane in a CVD batch furnace system is evaluated, particularly for use as a barrier material to enable Al-contacting of GaN diodes. These Al-B diodes could provide an option for fabricating low-leakage diodes that are compatible with complementary metal-oxide-semiconductor (CMOS) processing at industrially attractive high throughput. The bulk B has high resistivity, which, combined with the fact that non-uniformities in the nm range, are typical due to gas depletion along the furnace tube and gives uncontrollable, often high diode series resistance. A simulation study shows that Al-B could, nevertheless, be used as a gate stack in HEMTs for low-frequency power applications.

Active RCD adaptive voltage balancing control strategy for high-voltage uncontrolled rectifier valve

The voltage balance of the series diodes is the premise to ensure the stable and reliable operation of the high voltage uncontrolled rectifier valve. When traditional RC and RCD voltage balancing methods are applied to high voltage uncontrolled rectifier valves in far-reaching offshore wind farms, the complex and changeable operating environment poses a challenge to the anti-interference of the balance effect of the snubber circuit. In this paper, an active RCD adaptive voltage balancing control strategy with strong anti-interference ability is proposed based on the establishment of the active RCD voltage balancing model of the high voltage uncontrolled rectifier valve. The parameter tuning method of the active RCD snubber circuit is given, and the auto-PID control strategy of the active RCD snubber circuit is proposed according to its nonlinear time-varying characteristics. The simulation example verifies that the active RCD adaptive voltage balancing strategy of the high voltage uncontrolled rectifier valve has strong anti-interference performance, which provides a reference for the design of the high voltage uncontrolled rectifier valve voltage sharing system in the far-reaching offshore wind farm.

Extremely high frequency Schottky diodes based on single GaN nanowires

Gallium nitride (GaN) is one of the most promising materials for high-frequency devices owing to its prominent material properties. We report on the fabrication and study of a series of Schottky diodes in the ground-signal-ground topology based on individual GaN nanowires. The electrical characterization of I–V curves demonstrated relatively high ideality factor value (about 6–9) in comparison to the planar Au/GaN diodes that can be attributed to the nanowire geometry. The effective barrier height in the studied structures was defined in the range of 0.25–0.4 eV. The small-signal frequency analysis was employed to study the dependency of the scattering parameters in the broad range from 0.1 to 40 GHz. The approximation fitting of the experimental data indicated the record high cutoff frequency of about 165.8 GHz.

A novel double RESURF SOI-LIGBT with dynamic avalanche immunity and low losses

A novel, trench gates, double reduced surface field, lateral insulated gate bipolar transistor based on silicon-on-insulator (SOI-LIGBT) is proposed and investigated. A p-top layer connected to the emitter via two series diodes and n-rings surrounding the bottom of trench gates are used to reduce the on-state voltage drop (V CE(sat)) and turn-off loss (E off). A deep trench with a p-ring is introduced to form a gate-drain shorted positive channel metal oxide semiconductor, which can automatically raise the potential of the p-ring during turn-off so as to enhance the dynamic avalanche immunity. Besides, the deep trench with a p-ring can shield the high electric field from n-rings at the blocking state, which avoids the breakdown of n-rings. Simulation results indicate that the proposed LIGBT can be safely turned off even under a bus voltage equal to the breakdown voltage (V B), and V CE(sat) under E off = 1 mJ cm−2 can be 24% lower than that of the conventional LIGBT.

A dual-band, polarization-insensitive, wide-angle metasurface array for electromagnetic energy harvesting and wireless power transfer

A dual-band, polarization-insensitive, wide-angle metasurface array is presented in this article for electromagnetic (EM) energy harvesting in the UMTS-2100 band and Wi-Fi band. The metasurface unit cell is composed of two rings (each with four splits) nested in a centrosymmetric manner. The proposed metasurface array energy harvester consists of periodic array unit cells, a single series diode rectifier, and a load. The design of interconnected unit cells to form energy flow channels enhances the power density of the array terminals, thus improving the ability of the metasurface array to capture energy. In addition, the proposed resonant structure is centrosymmetric, so that consistent and effective collection efficiency can be obtained under different polarizations as well as at wide angular incidence. Moreover, the designed rectifier circuit enables the absorber to rectify dual bands simultaneously at low input power density. The prototype of the finite array is fabricated and tested in an anechoic chamber. The results show that the collection efficiency of the proposed metasurface array can reach 64.8% and 41.1% at two frequencies when the available power density reaches 46.4 μW/cm2.

Bias dependent NDR in TiO2/NiO heterojunction diodes

TiO2/NiO thin film heterojunction diodes are fabricated using electron beam evaporation and DC sputtering techniques. Three different thicknesses of NiO (58, 82, and 160 nm) are combined with a TiO2 film of about 80 nm thick. The common device configuration is FTO/TiO2/NiO/Au with a 4 mm sq. device area. The thickness dependent diode I-V characteristics were analyzed; with the increase in thickness, the diode knee voltage, series resistance, and ideality factor have reduced. All the devices exhibit a high diode ideality factor, which means the diode currents are not limited by drift, diffusion, or recombination at the space charge region. The high ideality factor points to the presence of interface states, spatial inhomogeneities, or tunneling in the devices. Further, the bias dependent negative differential resistance (NDR) in I-V characteristics and the presence of an anomalous peak in C-V characteristics were analyzed, which claimed the presence of interfacial trap states, defects, or tunneling in the diodes. The Fowler-Nordheim tunnel model was applied to the devices and the field enhancement factors were calculated as −14.3, −9.3, and −9.2 for the diodes in the increasing order of thickness. The tunneling phenomenon was confirmed as trap-assisted indirect tunneling. Also, the temperature dependence of NDR was studied.