Types Of Diodes Research Articles

Diode type unidirectional conduction in Hall measurement of magnetic honeycomb lattice

Artificial magnetic honeycomb lattice is emerging as a new platform for spintronics research applications, as evidenced from recent findings of magnetic diode effect and collective magnetic switching phenomena in different lattice geometries. In this report, we present Hall measurements on thermally tunable artificial magnetic honeycomb lattice. Experimental investigation using detailed Hall probe measurements reveals diode-type unidirectional conduction in both longitudinal and Hall resistances. The unidirectional conduction persists to low temperature but remains unaffected to modest application of perpendicular magnetic field. The behavior can be understood in terms of topological magnetic charges that arise on the vertices of honeycomb lattice and affect electrical transport properties. The experimental finding can be utilized for the design of spintronic logic devices.

The Effects of Light Treatments on Growth and Flowering Characteristics of Oncidesa Gower Ramsey ‘Honey Angel’ at Different Growth Stages

In our previous work, we observed that Oncidesa Gower Ramsey ‘Honey Angel’ (HA) plants became stunned on hot summer afternoons, and the seasonal trend in solar radiation affected its production schedule by limiting flower yield and quality. The objective of this work was to study the growth and flowering characteristics of HA pseudobulbs at three stages of growth (G2–G4) in response to three types of light-emitting diode (LED) lighting treatments, including full spectrum (FS), deep red/white-medium blue (DR/W-MB), and deep red/white-low blue (DR/W-LB), for two additional time intervals. The supplementary LED lighting time intervals (S) applied daily were carried out for 1 h (4:00~5:00 a.m., as S-1) or 2 h (4:00~6:00 a.m., as S-2) from March to September, 2022. Natural light without supplemental lighting was the control. The length of pseudobulb (PL), width of pseudobulb (PW), thickness of pseudobulb (PT), length of inflorescence (FL), number of branches (FB), number of florets (FN), and days to flowering (FD) per plant were recorded andcalculated when 80% of florets became mature. Light treatments significantly affected all pseudobulb growth and flower quality traits at different Gs, especially pseudobulb length (PL) and flower number (FN) under different LED types and lighting time intervals. MB-1 treatment promoted PT at both G3 and G4, whereas MB-2 treatment increased PW at both G2 and G4. Both MB-1 and LB-1 treatments had augmented effects on PL, respectively, at G2 and G3. The PW, FL, FB, and FN increased with additional light time and reached maxima under MB-2 treatment at G4 compared to other treatments and controls. Early flowering and an increased number of flowers at G4 were observed in plants grown under MB-2 treatment. Controlling light quality and supplementary light time intervals enables the production of HA plants with the desired growth and flowering quality characteristics of the pseudobulbs.

Injection-limited and space-charge-limited conduction in wide bandgap semiconductors with velocity saturation effect

Carrier conduction in wide bandgap semiconductors (WBS) often exhibits velocity saturation at the high-electric field regime. How such effects influence the transition between contact-limited and space-charge-limited current (SCLC) in a two-terminal device remains largely unexplored thus far. Here, we develop a generalized carrier transport model that includes contact-limited field-induced carrier injection, space charge, carrier scattering, and velocity saturation effect. The model reveals various transitional behaviors in the current–voltage characteristics, encompassing Fowler–Nordheim emission, trap-free Mott–Gurney (MG) SCLC, and velocity-saturated SCLC. Using GaN, 6H–SiC and 4H–SiC WBS as examples, we show that the velocity-saturated SCLC completely dominates the high-voltage (102–104 V) transport for typical sub-μm GaN and SiC diodes, thus unraveling velocity-saturated SCLC as a central transport mechanism in WBG electronics.

Development of a nanosecond high voltage pulser based on Semiconductor Opening Switch

Nanosecond pulser is widely used in beam injection and extraction. Semiconductor Opening Switch (SOS) is a type of high voltage diode with P+-P-N-N+ semiconductor structure, which has a great application prospect in pulse power technology for its notably short switching-off time, high repetition rate and large working current. The cutoff time of the SOS is dependent on the duration and amplitude of the pumping current, which may reach thousands of amperes. A two-stage magnetic compression pumping circuit without external demagnetization cicuits is proposed to meet the operational requirements of SOS. The circuit was simulated by Pspice, which confirmed the principle of the circuit. A prototype of the pulser was constructed based on the simulation analysis. The experiments indicated that the reverse pumping current with amplitude of 460 A and duration of 18 ns, and a 16 kV, duration of 14 ns pulse was generated on the load of 50 Ω. The design, simulation and the test results of the nanosecond high voltage pulser are presented in the paper.

Understanding Transient Ionic Diode Currents and Impedance Responses for Aquivion-Coated Microholes.

Ionic diode based devices or circuits can be applied, for example, in electroosmotic pumps or in desalination processes. Aquivion ionomer coated asymmetrically over a Teflon film (5 μm thickness) with a laser-drilled microhole (approximately 10 μm diameter) gives a cationic diode with a rectification ratio of typically 10-20 (measured in 0.01 M NaCl with ±0.3 V applied bias). Steady state voltammetry, chronoamperometry, and electrochemical impedance spectroscopy data are employed to characterize the ionic diode performance parameters. Next, a COMSOL 6.0 finite element model is employed to quantitatively assess/compare transient phenomena and to extract mechanistic information by comparison with experimental data. The experimental diode time constant and diode switching process associated with a distorted semicircle (with a typical diode switching frequency of 10 Hz) in the Nyquist plot are reproduced by computer simulation and rationalized in terms of microhole diffusion-migration times. Fundamental understanding and modeling of the ionic diode switching process can be exploited in the rational/optimized design of new improved devices.

Carbon Dioxide Concentration Estimation in Nonuniform Temperature Fields Based on Single-Pass Tunable Diode Laser Absorption Spectroscopy.

We propose a novel technique to accurately predict carbon dioxide (CO2) concentrations even in flow fields with temperature gradients based on a single laser path absorption spectrum measurement and machine learning. Concentration measurements in typical tunable diode laser absorption spectroscopy are based on a ratio of two integrated absorbances, each from a spectral line with different temperature dependence. However, the inferred concentrations can deviate significantly from the actual concentrations in the presence of temperature gradients. Furthermore, it is also difficult to find an analytical expression to compensate for the effect of nonuniform temperature profiles on concentration measurements. In this study, the entire absorption feature was considered since its shape and peak intensities vary with temperature and concentration. Specifically, a predictive model is obtained in a data-driven manner that can identify and compensate for the effect of a nonuniform temperature field on the spectrum. Despite a very detailed understanding of the CO2 absorption spectrum, it is nearly impossible to collect sufficient spectra for model acquisition by varying all temperature gradient conditions. Therefore, the model was obtained using only simulated data, much like the concept of a "digital twin". Finally, the predictive performance of the acquired model was verified using experimental data. In all test cases, the predictive performance of the model was superior to that of the two-line method. Additionally, a gradient-weighted regression activation mapping analysis confirmed that the model utilizes both the peak intensities as well as the change in the shape of absorption lines for prediction.

Transient Current Simulations: Benchmark of Numerical Tools for Proton, Electron, and Alpha Irradiation in Solid-State Detectors

The simulation of charge collection in solid state detectors (SSD) can be carried out with TCAD or Shockley-Ramo paradigms. These two paradigms have their limitations when simulating a large variety of cases, spanning from types of radiation, energy ranges, substrate doping concentration and applied bias. The aim of this paper is to explore the limits of these tools for the energy ranges of protons and electrons of the Earth’s radiation belts, as well as establish a benchmark of the different simulation codes that implement these paradigms. Proton, electron and alpha irradiation are carried out using a fast current amplifier and several different diodes. A 1D TCAD code has been developed and is presented here. Comparisons are then made with the other calculation paradigms for different types of irradiation conditions and diodes, showcasing which codes work best for the different configurations.

Investigation of the Boron removal effect induced by 5.5 MeV electrons on highly doped EPI- and Cz-silicon

This study focuses on the properties of the BiOi (interstitial Boron–interstitial Oxygen) and CiOi (interstitial Carbon–interstitial Oxygen) defect complexes by 5.5MeV electrons in low resistivity silicon. Two different types of diodes manufactured on p-type epitaxial and Czochralski silicon with a resistivity of about 10 Ω⋅cm were irradiated with fluence values between 1 × 1015cm-2 and 6 × 1015cm-2. Such diodes cannot be fully depleted and thus the accurate evaluation of defect concentrations and properties (activation energy, capture cross-section, concentration) from Thermally Stimulated Currents (TSC) experiments alone is not possible. In this study we demonstrate that by performing Thermally Stimulated Capacitance (TS-Cap) experiments in similar conditions to TSC measurements and developing theoretical models for simulating both types of BiOi signals generated in TSC and TS-Cap measurements, accurate evaluations can be performed. The changes of the position-dependent electric field, the effective space charge density Neff profile as well as the occupation of the BiOi defect during the electric field dependent electron emission, are simulated as a function of temperature. The macroscopic properties (leakage current and Neff) extracted from current–voltage and capacitance–voltage measurements at 20°C are also presented and discussed.

Overcoming voltage fluctuation in electric vehicles by considering Al electrolytic capacitor-based voltage stabilizer

Battery pack used in electrical vehicles (EVs) have developed fastly nowadays and are important due to its capability to stores electric charge. However, it is still found that there is an electrical voltage fluctuations due to sudden load changes or faults in the power system. To overcome this problem, the conventional strategy focuses on using voltage stabilizer with inductor-capacitor resonant circuits, leaving the problem of using capacitors at cryogenic temperatures. Herewith, we design a vehicle automatic voltage stabilizer (VAVS) operating at room temperature. The VAVS consists of nine main components, including resistors, capacitors, transistors, and diodes arranged with a specific composition to stabilize the voltage. By considering Al electrolytic capacitor, type of diode, resistor, and transistor, the VAVS device stabilizes the input voltage from 10-15V to obtain an output voltage of 12V. Then, by varying the engine rotation speed of vehicle, VAVS applied in vehicle battery supplies a constant voltage of about 12.1 V. The lowest line regulation analysis reveals a regulated voltage fluctuation of 0.17%/V. Our result shows that VAVS design works at room temperature, overcomes the voltage fluctuation and complies with the standard regulation of voltage stabilizers.

Reverse compositional strategy of multiple quantum wells for the AlGaN-based deep-ultraviolet laser diodes

Due to the high activation energy/ionization energy as Mg increases, Al-rich AlGaN-based deep-ultraviolet (DUV) laser diodes have a structure that is difficult to perform Mg p-doping. The performance of this type of laser diode is affected by the content of Al in the quantum barriers of multiple quantum wells, and reducing the Al content in the laser diodes may simplify its structure and make Mg p-doping less difficult. The proposed device can be improved by adopting the reverse compositional strategy of multiple quantum wells with the Al content of quantum barriers 10% lower than that of quantum wells as opposed to the reference device where the Al content of the quantum barriers is 10% higher than that of the quantum wells. The simulation results have been observed theoretically in terms of the performance parameters such as band diagrams, optical confinement factor, peak gain, emitted power, stimulated recombination rate, and carrier concentration. Two deep ultraviolet laser diode devices have been analyzed in this study within the wavelength range of 267 nm. The proposed device has superior performance with a larger optical confinement factor and increased output power with reduced injection current.

VWM-DCRNN: A Method of Combining Signal Processing With Deep Learning for Fault Diagnosis in Single-Phase PWM Rectifier

Based on variational mode decomposition and dual model of convolutional recurrent neural network (VMD-DCRNN), a novel diagnosis method is proposed to discover the faults of IGBTs, diodes and series resonant circuit in single-phase pulse width modulation (PWM) AC-DC rectifier, an important part of traction power supply system of high-speed railway. By virtue of the combination of signal processing and deep learning schemes, the multi-scale feature information for fault diagnosis is extracted by regarding the input current of the rectifier and the voltage of dc side as the original signal. More clearly, VMD is adopted to decompose the original signal to a series of intrinsic mode function components (IMFs). Then, the submodel of current is designed to detect the fault types of IGBTs and diodes. Meanwhile, the submodel of voltage is established to identify the fault types of series resonant circuit. These IMFs are fed into DCRNN consisting of the two submodels for training and testing. Finally, the features extracted from the two submodels are integrated and converted to label space to complete fault diagnosis. Experimental results show that the proposed VMD-DCRNN algorithm is superior to the single-channel models, reaching 96.27%.

Study on collection and retention efficiencies of a new integrated collector storage solar water heating system using a planar thermal diode: an experimental study.

Thermal diodes are a novel method to rectify the heat transfer mechanism and help reduce heat losses in solar thermal collectors during non-collection periods. The current study introduces and analyzes a new planar thermal diode integrated collector storage (ICS) solar water heating system using an experimental approach. This thermal diode ICS system has a simple, affordable structure composed of two parallel plates. Water serves as a phase change material to transfer heat through evaporation and condensation inside the diode. Three scenarios were considered to assess the dynamics of the thermal diode ICS: atmospheric pressure, depressurized thermal diodes, and Ppartial = 0, - 0.2, and - 0.4bar. The water temperature reached 40°C, 46°C, and 42°C in Ppartial = 0, - 0.2, and - 0.4bar, respectively. The heat gain coefficients are 38.61, 40.65, and 39.26 W/K, while the heat loss coefficients are 9.56, 5.16, and 7.03 W/K in Ppartial = 0, - 0.2, and - 0.4bar, respectively. The optimum heat collection and retention efficiencies are 45.3% and 33.5% in Ppartial = - 0.2bar. Hence, there is an optimum partial pressure to achieve the best performance, equal to - 0.2bar. The acquired results illustrate the robustness of the planar thermal diode in reducing heat losses and rectifying the heat transfer mechanism. Furthermore, despite the simple structure of the planar thermal diode, its efficiency is as high as that of other types of thermal diodes analyzed in recent studies.

Carrier density non-pinning at stripe edges and widened lateral far field due to longitudinal temperature variation in broad-area high power diode lasers

Broad area lasers operating at high power with improved beam quality are needed in many applications. In typical high-power diode lasers with asymmetric facet coating, it is observed that the carrier density fails to completely pin above threshold with significant levels of lateral carrier accumulation (LCA) at the front facet stripe edges. Systematic experimental data are presented to quantify such non-pinning and its effect on lateral far field in multiple diode lasers with varying longitudinal temperature variation (LTV) using spontaneous emission imaging. LTV is quantified and correlated with the carrier accumulation and its dependence on facet reflectivity and cavity length. Results of measurements under continuous wave (CW) and quasi-CW conditions are used to regulate the level of heating and, hence, to isolate the contribution of LTV and optical field profile. Conventional long resonator asymmetric-coated devices show a twofold increase in LCA from threshold to 10 A current at the front stripe edge, but LCA varies less than 20% for lower facet asymmetry or short resonators. Similarly, strong temperature driven far field broadening is observed for conventional long-resonator asymmetric-coated devices (3°–4° variation with temperature at 10 A), which is strongly reduced for lower facet asymmetry or short resonators (<1° at 10 A).

High Breakdown Voltage GaN Schottky Diodes for THz Frequency Multipliers

Quasi-vertical gallium nitride (GaN) Schottky diodes on silicon carbide (SiC) substrates were fabricated for frequency multiplier applications. The epitaxial structure employed had an n− layer of 590 nm with doping 6.6 × 1016 cm−3, while the n+ layer was 950 nm thick, with doping 2 × 1019 cm−3. Potassium hydroxide (KOH) chemical surface treatment before Schottky contact metallization was employed to study its effect in improving the diode parameters. The KOH-treated diode demonstrated a breakdown voltage of − 27.5 V, which is the highest reported for this type of diode. Cut-off frequencies around 500 GHz were obtained at high reverse bias (− 25 V) in spite of high series resistance. The result obtained in breakdown voltage value warrants further research in surface treatment and post-annealing of the Schottky contact optimization in order to decrease the series resistance.

Metal-insulator-semiconductor type diode based on implanted β-Ga2O3 epilayers grown on sapphire substrate by metalorganic chemical vapor deposition

Conductive β-Ga2O3 epilayers grown on the sapphire substrate using metalorganic chemical vapor deposition (MOCVD) were studied by Si-ion implanted. A metal-insulator-semiconductor diode (MISD) was fabricated using undoped and Si implanted β-Ga2O3 epitaxial layer. The electrical and carrier transport properties of the different MISD with different distance between cathode and anode contact ranging from 10 to 200 μm is studied. The various parameters such as forward current density, reverse breakdown voltage and ideality factor of the diodes has been calculated from the current-voltage curve. A reverse breakdown voltage of about 1.1 kV was observed in case of anode-cathode distance of 200 μm.

Control of Carrier Polarity and Schottky Barriers in Layered PdSe2 Field-Effect Transistors

Palladium diselenide (PdSe2) has been discovered as an intriguing two-dimensional (2D) semiconductor for its unique pentagonal crystalline structure, electrical and optical anisotropy, thickness-modulated band gap, robust air stability, and high carrier mobility, demonstrating great potential in field-effect transistors (FETs), photodetectors, and thermoelectric devices. Controlling the carrier polarity and electrical contact Schottky barriers is of great significance for realizing high-performance PdSe2 optoelectronic devices. Here, by combining work-function measurement and electrical transport, we observe a thickness-modulated carrier polarity transition in layered PdSe2 FETs from n-type unipolar to intrinsic ambipolar and p-type unipolar behavior by simply varying the number of layers of PdSe2. Due to the weak Fermi-level pinning in few-layer PdSe2, n-type and ambipolar FETs are achieved by contacting PdSe2 to Sc, Ti, and Pd electrodes, respectively. The Schottky barrier heights are determined by temperature-dependent transport, showing a 15 meV barrier for the Sc contact at the electron side and 62 and 93 meV barriers for Ti and Pd contacts, both at the hole side, respectively. We further demonstrate ozone-treatment-induced hole doping in PdSe2, which effectively converts the PdSe2 FETs from n-type to p-type. The doping is robust in the ambient environment over 3 months. In-plane homojunction on a PdSe2 flake is realized by selective ozone doping, demonstrating typical diode rectifying behavior. The ability to control the carrier polarity and Schottky barriers in layered PdSe2 makes this 2D semiconductor highly feasible for complementary metal-oxide semiconductor device integration and high-performance photodetectors based on atomically thin p–n junctions.

Organic and Hybrid Diode Features of an n-Type 1,8-Naphthalimide Derivative

Organic–inorganic hybrid photodiodes have garnered research interest to achieve high-performance optoelectronic devices with longer lifetime. In the present study, a fluorescent 1,8-naphthalimide (NI) derivative BHSHNI was synthesized through bromination of 3-hydroxy naphthalic anhydride and subsequent imidation reaction with salicyloyl hydrazide. The IR, NMR and mass spectrometry studies confirmed the molecular structure of the NI derivative. Intramolecular charge transfer was confirmed using theoretical and fluorescence emission studies. Thermal investigations suggested good stability of BHSHNI and cyclic voltammetry indicated an electrochemical band gap of 1.10 eV. Surface uniformity and pit-free morphology was observed in SEM and AFM images of thin films formed by BHSHNI. The organic (PEDOT:PSS) and hybrid (organic–inorganic) p–n type diodes were successfully constructed using BHSHNI. The hybrid diode exhibited better features with ideality factors of 9.3 and 15.2 in dark and visible light, respectively, with a dielectric constant of 7.65 at 30 kHz. The calculated responsivity of the hybrid diode was found to be 66.26 mu mathrm{A}/mathrm{W}. The device incorporating BHSHNI as functional material with NiO can be further explored for photodiode applications.Graphical

Epitaxial SiC Dosimeters and Flux Monitoring Detectors for Proton Therapy Beams.

The exceptional optoelectronic properties and high radiation resistance of epitaxial silicon carbide make this material attractive for high-energy beam dosimetry and radiation monitoring, especially when strict requirements such as high signal-to-noise ratios, high time and spatial resolutions and low detectivity levels are required. A 4H-SiC Schottky diode has been characterized as a proton-flux-monitoring detector and dosimeter under proton beams for proton therapy. The diode was composed of an epitaxial film grown on 4H-SiC n+-type substrate equipped with a gold Schottky contact. The diode was embedded in a tissue-equivalent epoxy resin and then characterized in terms of capacitance vs. voltage (C-V) and current vs. voltage (I-V) characteristics in the dark in the range of 0-40 V. The dark currents at room temperature are in the order of 1 pA, while the doping and active thicknesses extracted from the C-V are 2.5 × 1015 cm-3 and 2-4 μm, respectively. Proton beam tests have been carried out at the Proton Therapy Center of the Trento Institute for Fundamental Physics and Applications (TIFPA-INFN). They have been carried out with energies and extraction currents of 83-220 MeV and 1-10 nA, respectively, as typical for proton therapy applications, corresponding to dose rates in the range of 5 mGy/s to 2.7 Gy/s. The I-V characteristics measured under proton beam irradiation at the lowest dose rate showed a typical diode photocurrent response and a signal-to-noise ratio well above 10. Investigations with null bias evidenced a very good performance in terms of the diode's sensitivity, fast rise and decay times and response stability. The diode's sensitivity was in agreement with the expected theoretical values, and its response was linear throughout the whole investigated dose rate range.

Fabrication and photosensitivity analysis of MIS Schottky barrier diodes with different molar concentrations of MoO3 thin films

We made exceptionally sensitive MIS structured diodes with positive photosensitivity in this case utilizing a single-phase crystalline material. With (0.02, 0.04, 0.06 and 0.08 M) different molar concentration and an ideal substrate temperature of 500 °C, MoO3 layer thin films were effectively produced on a glass substrate using the JNSP approach. The mean crystallite size of the films was found to decrease and their associated lattice parameters improved within molar concentration. Single-phase crystalline MoO3 films with orthorhombic crystal structure were detected in XRD analysis. Through FESEM images small plate-like surface morphology was seen to be randomly distributed. When O atomswere added to the Mo matrix, it improved optical absorption and reduced Eg values, which was investigated using the UV–Vis spectrum. When there is a larger concentration of Mo, the current–voltage (I–V) characteristics show the highest dc with low Ea values. For Cu/MoO3/p-Si type diodes, it was discovered that their corresponding ideality factor (n) decreased as the light intensity of the diodes increased to 120 mW/cm2. Significant photodiodemetrics including PS increased with Mo, and in particular the MIS diode manufacturedwith its 0.08 M exhibited superior results in which a remarkable higher responsivity was measured, also contributed to the improved performance.

CMOS-compatible electro-optical SRAM cavity device based on negative differential resistance

The impending collapse of Moore-like growth of computational power has spurred the development of alternative computing architectures, such as optical or electro-optical computing. However, many of the current demonstrations in literature are not compatible with the dominant complementary metal-oxide semiconductor (CMOS) technology used in large-scale manufacturing today. Here, inspired by the famous Esaki diode demonstrating negative differential resistance (NDR), we show a fully CMOS-compatible electro-optical memory device, based on a new type of NDR diode. This new diode is based on a horizontal PN junction in silicon with a unique layout providing the NDR feature, and we show how it can easily be implemented into a photonic micro-ring resonator to enable a bistable device with a fully optical readout in the telecom regime. Our result is an important stepping stone on the way to new nonlinear electro-optic and neuromorphic computing structures based on this new NDR diode.