Diode Research Articles

A Novel Three-Phase Switched-Capacitor Five-Level Multilevel Inverter with Reduced Components and Self-Balancing Ability

This paper proposes a step-up 3-Ф switched-capacitor multilevel inverter topology with minimal switch count and voltage stresses. The proposed topology is designed to provide five distinct output voltage levels from a single isolated dc source, making it suitable for medium and low-voltage applications. Each leg of the proposed topology contains four switches, one power diode, and a capacitor. The switching signals are also generated using a staircase universal modulation method. As a result, the proposed topology will operate at both low and high switching frequencies. To highlight the proposed topology’s advantages, a comparison of three-phase topologies wasperformed in terms of the switching components, voltage stress, component count per level factor, and cost function withthe recent literature. The topology achieved an efficiency of about 96.7% with dynamic loading, and 75% of the switches experienced half of the peak output voltage (VDC), whereas the remaining switches experienced peak output voltage (2VDC) as voltage stress. The MATLAB/Simulink environment was used to simulate the proposed topology, and a laboratory prototype was also built to verify the inverter’s theoretical justifications and real-time performance.

Investigation of the structural and morphological features of TiO2:8OBA composites for MIS semiconductor diodes

In this study, a liquid crystal 8OBA-doped TiO2 composite was formed on a p-Si substrate using the ultrasonic spray coating method. The characterization of the un-doped and doped films produced was carried out by SEM-EDS, XRD and UV–vis measurements. SEM/EDS analysis showed that the TiO2:8OBA composite completed the formation of a layer on the glass surface and exhibited a homogeneous distribution throughout the surface. XRD analysis of TiO2:8OBA composites showed that anatase and rutile crystal phases are belonging to TiO2 and CH based phase indicating 8OBA. In addition, as a result of UV–vis analysis, the optical band gap of 8OBA:TiO2 composite was calculated as 2.82 eV. Besides, the diode application of 8OBA doped and un-doped TiO2 thin film was performed. Charge transport processes of the diode were studied in detail by taking current–voltage measurements. The ideality factor, barrier height, series resistance and parallel resistance values were extracted using different methods.

Electric field induced migration of native point defects in Ga2O3 devices

While the properties of β-Ga2O3 continue to be extensively studied for high-power applications, the effects of strong electric fields on the Ga2O3 microstructure and, in particular, the impact of electrically active native point defects have been relatively unexplored. We used cathodoluminescence point spectra and hyperspectral imaging to explore possible nanoscale movements of electrically charged defects in Ga2O3 vertical trench power diodes and observed the spatial rearrangement of optically active defects under strong reverse bias. These observations suggest an unequal migration of donor-related defects in β-Ga2O3 due to the applied electric field. The atomic rearrangement and possible local doping changes under extreme electric fields in β-Ga2O3 demonstrate the potential impact of nanoscale device geometry in other high-power semiconductor devices.

Deep Level Transient Fourier Spectroscopy Investigation of Electron Traps on AlGaN/GaN-on-Si Power Diodes

Many kinds of defects are present in AlGaN/GaN-on-Si based power electronics devices. Their identification is the first step to understand and improve device performance. Electron traps are investigated in AlGaN/GaN-on-Si power diodes using deep level transient Fourier spectroscopy (DLTFS) at different bias conditions for two Schottky contact’s etching recipes. This study reveals seven different traps corresponding to point defects. Their energy level ET ranged from 0.4 eV to 0.57 eV below the conduction band. Among them, two new traps are reported and are etching-related: D3 (ET = 0.47–0.48 eV; σ ≈ 10−15 cm2) and D7 (ET = 0.57 eV; σ = 4.45 × 10−12 cm2). The possible origin of the other traps are discussed with respect to the GaN literature. They are proposed to be related to carbon and nitrogen vacancies or to carbon, such as CN-CGa. Some others are likely due to crystal surface recombination, native defects or a related complex, or to the nitrogen antisite: NGa.

Liquid metal gallium-based printing of Cu-doped p-type Ga2O3 semiconductor and Ga2O3 homojunction diodes

As a promising third-generation semiconductor, gallium oxide (Ga2O3) is currently facing bottleneck for its p-type doping. The doping process of conventional semiconductors usually introduces trace impurities, which is a major technical problem in the electronics industry. In this article, we conceived that the process complexity could be significantly alleviated, and a high degree of control over the results could be attained using the selective enrichment of liquid metal interfaces and harvesting the doped metal oxide semiconductor layers. An appropriate mechanism is thus proposed to prepare the doped semiconducting based on multicomponent liquid metal alloys. Liquid metal alloys with the certain Cu weight ratios in bulk are utilized to harvest Cu-doped Ga2O3 films, which result in p-type conductivity. Then, field-effect transistors were integrated using the printed p and n-type Ga2O3 films and demonstrated to own excellent electrical properties and stability. Au electrodes fabricated on the printed Ga2O3 and Cu-doped Ga2O3 layers showed good Ohmic behavior. Furthermore, high-power diodes are realized using printed p and n-type Ga2O3 homojunction through combining van der Waals stacking with transfer printing. The fabricated Ga2O3 homojunction diode exhibited good efficiency at room temperature, involving a rectification ratio of 103 and forward current density at 10 V (J@10 V) of 1.3 mA. This opens the opportunity for the cost-effective creation of semiconductor films with controlled metal dopants. The process disclosed here suggests important strategies for further synthesis and manufacturing routes in electronics industries.

Physics of semiconductor materials in high school: possibilities and challenges

The teaching of Science in High School prioritizes the substantive formation of subjects capable of understanding natural phenomena from laws, concepts and precise theoretical formulations. This appropriation of knowledge depends, in addition to the didactic aspects of teaching, on a modern curriculum, which prioritizes the technological advances produced by the different fields of science, contributing to the scientific training of students. Given this context, this article aims to discuss the importance and pedagogical possibilities of teaching the Physics of semiconductor materials in high school, considering the technological impact of these materials on modern society. To this end, a qualitative bibliographical study will be carried out, bringing together scientific works published in the last decade that emphasize the need for a curriculum focused on the Physics of the so-called 'active' components, represented mainly by the semiconductor diode and the transistor, completing the exposition of the study of electrodynamics. in high school. From the reflections of this work we prove the need to include the study of these materials to understand the main technologies present in the daily life of the digital society, making their users critical-reflective subjects of these resources, understanding their genesis, functionality, technical applicability, scope and evolution.

A New Seven-Level Transformer-Less Grid-Tied Inverter With Leakage Current Limitation and Voltage Boosting Feature

This article presents a new transformer-less grid inverter. The proposed topology can produce seven-level output voltage waveform using six power electronic switches and two power diodes. In addition, the recommended topology can limit the amplitude of leakage current in the photovoltaic (PV) systems, which is the major problem in grid-connected PV applications. The proposed inverted has some other benefits, such as voltage boosting capability, reactive power supporting, controlling both active and reactive power flows, reduced output filter size and lower total harmonic distortion of the injected current to the grid. Finally, the accurate performance of the recommended grid-tied structure is proved by the 620–1000 W laboratory prototype.

Microcontroller-Based Thermoelectrically Stabilized Laser Diode System

This work aims to describe the development of a prototype laser diode system along with its driver circuit and a stable microcontroller-based thermo-electric cooling system. The laser diode driver circuit was designed and simulated by using NI Multisim. The driver circuit was built using two LM317 ICs to control the voltage across the laser diode and current through the laser diode. The laser diode output power varies by varying the current across the laser diode through the driver circuit. The temperature of the laser diode rises with time, affecting the output power of the laser diode during a long period of operation. A microcontroller-based cooling system was designed and fabricated using thermoelectric coolers. The microcontroller controls the cooling system ON/OFF period to maintain the laser diode at a particular temperature by removing the excess heat produced during the lasing action. The laser diode with a microcontroller-based cooling system shows that the laser diode output power remains stable during a long period of operation.

Температурная зависимость дислокационной электролюминесценции в кремниевых светодиодах с кислородными преципитатами

Electroluminescence has been studied in silicon light-emitting diodes containing oxygen precipitates at temperatures of 40-300 K. Oxygen ion implantation and multistage anneals are used for fabrication of the diodes. Over all temperature range, spectra are well approximated by one Lorentz and four Gaussian curves. Lines of dislocation-related luminescence D1-D4 (the D1 line is described by Lorentz curve) and oxygen precipitates (OPs) are present in the spectra. At temperature variation, peak positions of the D1, OP and D2 lines coincide with temperature dependence of the forbidden gap width reduced by values of 356, 330 and 303 meV respectively. Build and quenching areas are observed on temperature dependences of the electroluminescence intensities of the D1, OP and D2 lines, the activation energies of the processes are determined, and reasons of their appearance are discussed.

A design of Fire Detector

Fires are detected by a simple circuit known as a fire alarm circuit, which then activates buzzers or sirens. The prompt identification of fires and the protection of people and property depend on the usage of fire alarm circuits. Security systems use smoke sensors and fire alarm circuits to help detect or stop danger. In public areas like theatres, malls, and other commercial buildings, smoke detectors and fire alarm systems must be installed. Utilising components that are readily available, such as the thermistor, LM358 germanium diode, LM341, and NE555, we developed five extremely simple fire alarm circuits. As independent devices, there are several high-priced and intricate fire alarm circuits available. The buzzer, the operational amplifier, and the thermostator are the only components in this very simple alarm circuit. A fire alarm system's primary objective is to alert people in advance of a fire so they may evacuate and take prompt action to lessen the fire's consequences as soon as possible. Both manually at a call point (remotely) and with the aid of detectors, alarms can be activated.

Design and Development of a Low-cost Integrated Dosimeter for External Beam Dosimetry in Radiation Oncology.

Radiation dosimeters play a crucial role in radiation oncology by accurately measuring radiation dose, ensuring precise and safe radiation therapy. This study presents the design and development of a low-cost printed circuit board (PCB) dosimeter and an integrated electrometer with sensitivity optimized for dose rates intended for use in megavoltage radiation therapy. The PCB dosimeter was designed in KiCad, and it uses a low-cost S5MC-13F general-purpose 1 kV 5A power diode as a radiation detector. The dosimeter is calibrated against a known dose derived from an ionization chamber and tested for dose linearity, dose rate dependence, field size dependence, and detector orientation dependence. The observed average dose differences between the delivered and measured doses for most measurements were found to be < 1.1%; the dose rate linearity between 100 MU/min and 1400 MU/min was found to be within 1.3%. This low-cost architecture could successfully be adapted further for a scalable, cost-effective dosimetry solution through firmware or circuit design.

Novel Zero-Voltage Zero-Current Transition Buck Converter With Minimal Impact of Active Auxiliary Cell on Overall Dynamics

This paper presents a novel zero-voltage zero-current transition DC/DC buck converter, which uses an active auxiliary resonant network to achieve soft switching operation of semiconductor switches and soft-recovery of power diodes over wide output power range and offers high efficiency. The auxiliary cell in the proposed converter does not cause any additional current stress on the semiconductor switches and has minimal impact on overall dynamics of the converter. Steady-state performance of the converter has been presented with detailed theoretical analysis of all operating modes. The design of auxiliary cell components and development of small signal model of the converter have been carried out from the mathematical equations depicting its dynamic behaviour. A closed loop voltage mode controller with a type III compensator has been developed for the converter to achieve the desired transient response under the influence of external disturbances. Power loss analysis and superiority of the proposed converter over other conventional configurations are also presented here. Finally, soft-switching behaviour and step-input transient response of the converter are verified by hardware experimentation on a 150W, 100 kHz prototype model. The experimental measurements have successfully validated the theoretically predicted behaviour of the converter.

Analysis of 1.2 kV GaN polarisation superjunction diode surge current capability

The surge current capability of power diodes is one of the essential parameters that needs to be considered for high power density operations in power electronic applications. Gallium Nitride (GaN) is emerging as the next generation of power semiconductor devices due to its superior material characteristics. This work presents the device working principle, characteristics, and the surge capability of 1200 V GaN polarisation superjunction (PSJ) hybrid diodes. The experimental results show that the GaN PSJ diode can withstand a surge current of 60 A which is around 8 times its rated current and a surge energy of 5.4 J. Additionally, despite having a merged PiN and Schottky structure, no bipolar current flow due to the activation of p-doped GaN can be observed until breakdown. This can also be confirmed through the device forward characteristic which shows a unique saturation behaviour at about 76 A without any bipolar region.

Non-contact thermometer behavior of (Y0.5In0.5)2O3:Yb3+,Er3+ solid solution.

Oxides are physically and chemically stable. Non-contact thermometer-Yb3+-Er3+ ions co-doped solid solution (Y0.5In0.5)2O3, is prepared by the regular solid method. The structural results obtained by XRD indicate that a pure phase solid solution (Y0.5In0.5)2O3 has been obtained. The solid solution (Y0.5In0.5)2O3 has a similar crystal structure, especially Y2O3 and In2O3 with the same space group (Ia3̄). Green emission from 500 to 600 nm is due to Er3+ 4f-4f transitions: 4S3/2 → 4I15/2 at 567 nm and 2H11/2 → 4I15/2 at 528 nm. Red emissions from 630 to 720 nm are attributed to Er3+: 4F9/2 → 4I15/2. UC luminescence changes greatly with laser diode power and Er3+ and Yb3+ content. Furthermore, the two-photon process is confirmed to be dominant between Yb3+ and Er3+ in oxide solid solution (Y0.5In0.5)2O3. Optical temperature sensitivity is also investigated systematically in order to explore the application of the oxide solid solution (Y0.5In0.5)2O3. The temperature-dependent green fluorescence at 528 and 567 nm was investigated with the range of 313-573 K. 0.316% K-1 is the maximum absolute sensitivity at 503 K, which is higher than most Yb3+/Er3+ co-doped systems. In addition, the solid solution (Y0.5In0.5)2O3:Yb3+,Er3+ has better thermal stability and stronger UC emission than a simple substance with excellent temperature sensing performance. It indicates that Yb3+-Er3+ ions co-doped (Y0.5In0.5)2O3 solid solution is a good candidate for optical temperature sensing.

Determination of the current-voltage characteristics of the photovoltaic cells using the CoachLabII+ measuring console

The Coach6 software and the CoachLabII+ measuring console coupled with a computer and equipped with appropriate voltage and current sensors were used to determine the current-voltage and power-voltage characteristics of the photovoltaic cells. The current-voltage and power-voltage characteristics for a single cell and cells connected in series and in parallel were tested depending on the light intensity. Using a simplified theoretical model of a photovoltaic cell based on the one-diode equivalent circuit and Shockley diode equation, the ideality factor, diode saturation current and source current were determined, fitting the appropriate theoretical relationship to the measurement results. Based on the current-voltage and power-voltage characteristics, the short-circuit current, open circuit voltage, maximum power, fill factor, conversion efficiency and load resistance were determined. The dependence of the determined parameters on the light intensity was discussed.

Modelling and Performance Analysis of CuPc and C60 Based Bilayer Organic Photodetector

An optoelectronic device model for organic photodetector based on bilayer structure has been presented. Drift-diffusion and optical-generation model from Synopsys tool have been incorporated and its optoelectronics behavior has been discussed. The model shows an outstanding rectifying behavior under dark condition due to the different work function of the electrodes. Photocurrent density of 6.64 mA/cm2 is found under the illumination of 3 W/cm2. To analyze rectifying behavior of current density-voltage characteristics of the organic photodetector, the curve has been fitted with the Shockley equation. The enhancement of ideality factor of diode current under illumination from that of dark current at forward bias is attributed to enhancement of recombination loss due to generation of photo-carrier and injection of carriers from electrodes. Almost equal probability of photocurrent spectra in the entire spectral region indicates equal probability of exciton generated and dissociated at the interface between CuPc and C60 layers. The detectivity of the proposed photodetector is calculated and it is in order of 1010 Jones at 650 nm due to high dark current density and recombination loss. The presence of interface trap density and large transport distance give evidence of low response speed in the device.

Indirect Thermographic Temperature Measurement of a Power-Rectifying Diode Die Based on a Heat Sink Thermogram

This article concerns the indirect thermographic measurement of the junction temperature of a D00-250-10 semiconductor diode. Herein, we show how the temperature of the semiconductor junction was estimated on the basis of the heat sink temperature. We discuss the methodology of selecting the points for thermographic measurement of the heat sink temperature and the diode case. The method of thermographic measurement of the heat sink temperature and the used measurement system are described. The simulation method used to obtain the temperature of the semiconductor diode junction on the basis of the thermographic measurement of the heat sink temperature, as well as the method of determining the emissivity and convection coefficients, is presented. In order to facilitate the understanding of the discussed issues, the construction of the diode and heat sink used, the heat flow equation and the finite element method are described. As a result of the work carried out, the point where the diode casing temperature is closest to the junction temperature was indicated, as well as which fragments of the heat sink should be observed in order to correctly estimate the temperature of the semiconductor junction. The indirect measurement of the semiconductor junction temperature was carried out for different values of the power dissipated in the junction.

Nonlinear Inertial Diode Model Considering the Dependence of Nonequilibrium Charge Carrier Lifetime on Direct Current to Improve Simulation of Radioelectronic Equipment

Introduction. Adequate modeling of semiconductor devices with a p–n-junction in reverse bias represents a relevant research problem. The existing quasistatic and non-quasistatic models fail to provide a satisfactory description for the dependence of nonequilibrium charge carrier lifetime on current density. This leads to significant simulation errors (tens of percent) at pulsed broadband signals. Simulation errors arise, because the existing models regard the lifetime as a constant value.Aim. To propose and investigate an equivalent circuit of a p–n-junction considering the dependence of the lifetime of nonequilibrium charge carriers on direct current, with the possibility of its simple integration into CAD.Materials and methods. The study was carried out on the example of a fast recovery silicon diode BAS16J with a p–n-junction manufactured by Nexperia. A modified diode model is proposed in the form of an equivalent circuit that considers the dependence of the lifetime of nonequilibrium charge carriers on the direct current of the p–njunction at high injection levels.Results. The discrepancy between the experimental and simulated curves did not exceed ±9 % under pulsed diode operation. The extraction of parameters in the proposed model is carried out conventionally, from the current-voltage and capacitance-voltage characteristics of the diode.Conclusion. The proposed non-quasistatic equivalent diode circuit can be used when designing radio electronic devices operated at short-pulse broadband signals. The proposed diode model can be easily implemented in modern CAD systems at the user level.

6LiF Converters for Neutron Detection: Production Procedures and Detector Tests

Several methods to detect thermal neutrons make use of the naturally occurring 6Li isotope, as it has a rather high cross-section for neutron capture followed by a decay into an alpha particle and a triton. Due to the high chemical reactivity of lithium, the use of the stable isotopic salt 6LiF is generally preferred to the pure 6Li. The typical method for depositing thin layers of 6LiF on suitable substrates, therefore creating so-called neutron converters, is evaporation under vacuum. The evaporation technique, as well as a newly developed chemical deposition process, are described along with their benefits and drawbacks, and the results of neutron detection tests performed with the two types of converters coupled to silicon diodes show convenient performances.

A quadratic step‐up dc‐dc converter with high gain, reduced voltage stress, and component counts

SummaryIt is safe to say that the topic of step‐up dc–dc converters is one of the most popular issues in power electronics. Since the demand for high‐gain and high‐efficiency converters with optimal component counts has increased drastically, more new step‐up topologies have been innovated. Continuing past efforts, the paper proposes a new single‐switch non‐isolated step‐up dc–dc converter based on the basic quadratic boost converter (QBC). High boost factor, high efficiency, continuous input current, reduced voltage stresses on the switch and power diodes, and an appropriate required number of elements compared to the obtained boost factor are the most significant achievements of this topology, which satisfy most of the essential design goals. Compared to the basic QBC, the voltage gain has been increased five times further by integrating a new coupled inductor–capacitor‐based impedance network into the basic quadratic circuit. In this article, the theory and operating principle of the topology for both continuous and discontinuous current modes (CCM and DCM) are discussed in detail. To verify the theory, experimental results are also presented. Results show that the converter has reached 12 times gain, about 95% efficiency, and up to one‐third less voltage stresses on semiconductors.