Diode Resistance Research Articles

Research on Schottky diode with high rectification efficiency for relatively weak energy wireless harvesting

Wireless power harvesting technology can convert RF energy into DC energy, but the main RF energy density in the environment is relatively low. Therefore, in order to improve the rectification efficiency of the transmission system under 2.45 GHz relatively weak energy density, this paper studies the influencing factors of rectification efficiency. Based on device optimization, a silicon layer combination contact GeSn Schottky diode structure for 2.45G relatively weak energy harvesting is proposed in this paper, which is simulated and verified using Silvaco and ADS simulation tools. The results show that the current responsivity and the turn-on voltage of GeSn Schottky diode with Si layer is about 21.5 A W −1 and 0.18 V, respectively. Under the condition of 2.45 GHz and −10 dBm relatively weak energy density, its rectification efficiency is about 10%, and when the input energy is 0 dBm, its rectification efficiency can reach 40%, twice that of ordinary Ge Schottky diodes. • Microwave wireless power transmission (MWPT) system is a device that converts RF energy into DC voltage, which can also deliver electrical energy in space without transmission lines. As the core device of rectifier circuit, the performances of Schottky diodes largely determine the rectification efficiency. • The turn-on voltage, series resistance and junction capacitance of Schottky diode are closely related to the rectification efficiency under relatively weak energy density. • 3. The material type and the work function difference between the metal and the semiconductor largely determine the turn-on voltage of the Schottky diode.

Power-Efficient Driver Circuit for Piezo Electric Actuator with Passive Charge Recovery

Piezoelectric actuation is a promising principle for insect-scaled robots. A major concern while utilizing a piezoelectric actuator is energy loss due to its parasitic capacitance. In this paper, we propose a new concept to recover the charge stored in the parasitic capacitance; it requires only three additional lightweight passive components: two diodes and a resistor. The advantages of our concept are its small additional mass and simple operating procedure compared with existing charge recovery circuits. We provided a guideline for selecting a resistor using a simplified theoretical model and found that half of the charge can be recovered by employing a resistor that has a resistance sufficiently larger than the forward resistance of the additional diode. In addition, we experimentally demonstrated the concept. With a capacitive load (as a replacement for the piezoelectric actuator), it was successfully observed that the proposed concept decreased the power consumption to 58% of that in a circuit without charge recovery. Considering micro aerial vehicle (MAV) applications, we measured the lift-to-power efficiency of a flapping wing piezoelectric actuator by applying the proposed concept. The lift force was not affected by charge recovery; however, the power consumption was reduced. As a result, the efficiency was improved to 30.0%. We expect that the proposed circuit will contribute to the advancement of energy-saving microrobotics.

Characteristic Test of Diode Based Multisim Software

In this study, a diode characteristic testing will be conducted, namely the characteristics of forward bias and reverse bias using Multisim software. Diode components are mostly applied to electronic circuits, so a simulation is needed to determine the performance of the diode before it is applied to the circuit. The test to be carried out this time includes making a forward bias circuit and back bias on a diode, describing the characteristics of the diode, determining the diode's working point for a particular condition, and determining dc diode resistance in the forward bias and reverse bias. From the results of testing the forward bias characteristic, it can be seen that the silicon diode IN 4001 in forward bias increases the small current until the diode voltage (Vd) reaches its knee voltage (Vk) around 0.6 V - 0.7 V. After going through knee stress (Vk), then the increase in large currents. The workings of diodes like this can be said as diodes with deviant or biased currents. Whereas the reverse bias current is almost constant (almost close to zero) even though the voltage is increased continuously until it reaches a voltage of 50 V. How it works like this is called a diode with reverse current.

Anisotropy of hydrogen plasma effects in bulk n-type β-Ga2O3

Bulk n-type β-Ga2O3 samples with orientation (−201) and (010) were exposed to a high density hydrogen plasma at 330 °C for 0.5 h. The effects were radically different for the two orientations. For the (−201) sample, H plasma exposure increased the net surface concentration of shallow donors from 2.7 × 1017 cm−3 to 2.6 × 1018 cm−3, with the shallow donors having an ionization energy close to 20 meV as deduced from the temperature dependence of the series resistance of Ni Schottky diodes. By sharp contrast, H plasma exposure of the (010) sample led to a strong decrease in the net shallow donor density from 3.2 × 1017 cm−3 to below 1015 cm−3 in the top 0.9 μm of the sample and to 3.2 × 1016 cm−3 near the edge of the space charge region at 0 V, with the total width of the region affected by plasma treatment being close to 1.1 μm. For both orientations, we observed a major decrease in the concentration of the dominant E2 traps near Ec-0.82 eV related to Fe acceptors. The deep trap spectra in hydrogenated samples were dominated by the E2* traps commonly ascribed to native defects in β-Ga2O3. The peak of these traps with a level near Ec-0.74 eV was masked in the starting samples by the peak of the E2 Fe acceptors present in high concentration, so that E2* only broadened the Fe peak on the low temperature side, but could be revealed by the modeling of the spectra. The concentration of the E2* center was not strongly affected in the hydrogen-treated samples with orientation (010), but in the (−201) samples, the concentration of the E2* peak was greatly enhanced. The results are discussed in conjunction with previous reports on hydrogen plasma treatment of β-Ga2O3 and on obtaining p-type conductivity in the surface layers of β-Ga2O3 crystals annealed in molecular hydrogen at high temperatures [Islam et al., Sci. Rep. 10, 6134 (2020)].

Čerenkov phonon radiation and phonon structure in electron emission, electroluminescence, and current–voltage characteristics of electroformed Al–Al2O3–Ag diodes

Electroforming of metal–insulator–metal (MIM) diodes is a non-destructive dielectric breakdown that results in a conducting filament in the insulator and changes the high resistance of the as-prepared MIM diode into a low-resistance state. It is a critical step in the development of conducting states between which switching can occur in memristors or resistive switching memories. Electroforming of Al–Al2O3–Ag diodes in vacuum results in the formation of a conducting Al2O3 filament. There are Ohmic contacts at the Al–Al2O3 and Al2O3–Ag interfaces. Electronic processes develop, such as voltage-controlled negative resistance in the current–voltage (I–V) characteristics, electron emission into vacuum (EM), and electroluminescence (EL). I–V curves, EM, and EL of three electroformed Al–Al2O3–Ag diodes with anodic Al2O3 thicknesses between 36 nm and 49 nm have been measured with 20 mV resolution between voltage steps. Periodic voltage structure occurs for the three electronic processes for applied voltages between the voltage threshold for EL, ∼2 V, and the maximum applied voltage, 11 V. The voltage peak period, 60 mV to 70 mV, is the same as the range of LO phonon energies of anodic Al2O3. The proposed mechanism is Čerenkov phonon generation by ballistic electrons whose velocity exceeds the velocity of sound in Al2O3. The phonons, in turn, modify the motion and number of electrons that are emitted into vacuum, that are responsible for EL radiation, and that contribute to conduction through the diode. The occurrence of LO phonons shows that the conducting filament is Al2O3, not Ag or Al. The phenomena may provide a new method of generating terahertz radiation.

Sr-doped yttrium nickel oxide-based photodetectors

In this research, Sr-doped yttrium nickel oxide-based photodetectors have been fabricated. The electrical properties of diodes have been analyzed by using Cheung and Norde methods. The ideality factors, barrier heights, and series resistances of diodes have been calculated under visible light at different irradiation intensities. In addition, the photoresponse behavior of photodetectors was investigated under visible light at different irradiation intensities. The highest responsivity (R) and detectivity (D*) were calculated as 25.34 mA/W and 7 × 84 1011 Jones, respectively. These results suggest that the photodetectors can be used optoelectronic device applications.

Влияние температуры протонного облучения на характеристики мощных высоковольтных карбид-кремниевых диодов Шоттки

For the first time, the effect of irradiation at high temperature (“hot irradiation”) by protons on the capacitance – voltage and current – ​​voltage characteristics of silicon carbide based semiconductor devices was studied. We investigated commercial high-voltage (blocking voltage of 1700 V) integrated 4H-SiC Schottky diodes. Irradiation was carried out by protons with an energy of 15 MeV at temperatures of 20-400 ° C. It has been established that the most sensitive to radiation parameter determining the radiation resistance of devices is the ohmic resistance of the base, which increases monotonically with increasing radiation dose D. It is shown that during “hot” irradiation, the radiation resistance of diodes significantly exceeds the resistance of diodes in low-temperature (“cold”) irradiation . It was concluded that, with increasing irradiation temperature, the rate of formation of deep centers in the upper half of the band gap of silicon carbide decreases.

Design and Testing of a Valveless Piezoelectric Pump with Conical Vortex Diodes

The valveless piezoelectric pump delivers fluid based on the difference of flow resistance of internal tube. In this paper, a vortex diode with conical tangential tube is proposed, which possesses the great characteristic of reverse cut-off, and the analysis of the forward and reverse flow resistance of the conical vortex diode is verified by finite element analysis. Then, a valveless piezoelectric pump with conical vortex diodes as the internal channel is designed, and the prototype is manufactured. The results of the output performance experiment show that the maximum output flow rate of the valveless piezoelectric pump is 10.44 g/min at the drive frequency of 45Hz, and the maximum output pressure is 560 Pa at the drive frequency of 35Hz. The proposal of the valveless piezoelectric pump provides a good reference for more new types of valveless piezoelectric pumps.

A model for predicting photovoltaic module performances

The present paper deals with the development of a simulation model for predicting the performances of a solar photovoltaic (PV) system operating under current meteorological conditions at the site location. The proposed model is based on the cell equivalent circuit including a photocurrent source, a diode, a series and shunt resistances. Mathematical expressions developed for modeling the PV generator performances are based on current-voltage characteristic of the considered modules. The developed model allows the prediction of PV cell (module) behavior under different physical and environmental parameters. The model can be extended to extract physical parameters for a given solar PV module as a function of temperature and solar irradiation. A typical 260 W solar panel developed by LG Company was used for model evaluation using Newton-Raphson approach under MATLAB environment in order to analyze its behavior under actual operating conditions. Comparison of our results with data taken from the manufacturer’s datasheet shows good agreement and confirms the validity of our model. Hence, the proposed approach can be an alternative to extract different parameters of any PV module to study and predict its performances.

I–V characteristic curve analysis of organic light emitting diode and the impact of equivalent circuit parameters on it

In this paper, by using an equivalent circuit, we examined V–I characteristic curve of an organic light-emitting diode. In this equivalent circuit, according to the multilayer structure of the organic light-emitting diode, intrinsic capacitance and ohmic resistance of layers’ junction are considered as the equivalent circuit elements. We investigated the impacts of temperature and equivalent circuit elements on the V–I characteristic curve. Furthermore, in this equivalent circuit, we have investigated voltage and current curve in term of frequency. Simulation has been done with the help of HSPICE and MATLAB software. The results can be used to improve the efficiency of the structure of organic light-emitting diode.

High rectification efficiency direct bandgap Ge1−xSnx Schottky diode for microwave wireless power transfer

Energy conversion efficiency is one of the core key indicators for evaluating the performance of microwave wireless power transmission (MWPT) system and how to improve the energy conversion efficiency of MWPT is one of the hotspots and focuses in the current research. Reducing the zero-bias resistance of the common core component Ge Schottky diode of the rectifier circuit can effectively improve the rectification efficiency of the rectifier circuit, thereby improving the energy conversion efficiency of the MWPT. In view of this, this paper proposes a direct bandgap Ge1−xSnx alloy (D-Ge1−xSnx) Schottky diode device structure for MWPT through modeling analysis and simulation design. D-Ge1−xSnx materials have twice the electron mobility of Ge materials, so D-Ge1−xSnx Schottky diodes have lower zero-bias resistance and are more suitable for MWPT. Based on the D-Ge1−xSnx Schottky diode spice model parameters, the ADS is used to simulate the rectifier circuit. The results show that the single-tube rectification efficiency can reach 77.5% under the condition of 2.45 GHz and 22 dBm energy density, and it is increased by 8.6% compared with the common HSMS-2820 Ge Schottky diode. The high rectification efficiency D-Ge1−xSnx Schottky diode proposed and designed in this paper can provide valuable reference for the design of the core components of the MWPT system rectifier circuit and the development of the energy conversion efficiency of the MWPT system.

Nanoscale ballistic diodes made of polar materials for amplification and generation of radiation in the 10 THz-range

We investigate ultrahigh frequency electrical properties of nanoscale n+−i−n+ diodes made of polar semiconductors. The calculations show that the coupling between optical vibrations of the lattice and the ballistic electrons strongly modifies and enhances the time-of-flight effects giving rise to narrow resonances of the diode impedance in the reststrahlen frequency range. Particularly, negative dynamic resistance is induced in close proximity to the optical phonon frequency. The resonant effects in the dynamic resistance of nanoscale GaAs and InP diodes are studied in detail. The obtained magnitudes of the negative dynamic resistance effect indicate that the nanoscale diodes are capable of generating electromagnetic radiation in the far-infrared spectral range under electric pumping.

An ON-State Voltage Calculation Scheme of MMC Submodule IGBT

The degradation of submodule (SM) insulated gate bipolar transistors (IGBTs) in a modular multilevel converter (MMC) can be monitored through their on -state voltages. This paper proposes a scheme to calculate the IGBT on -state voltages at rated current and normal junction temperature. The equations of on -state resistances are established based on Kirchhoff voltage laws (KVL) in one MMC arm for positive and negative current directions separately. The arm current, arm voltage, capacitor voltages, gate signals, and junction temperatures are utilized in the equations, and most of the signals are known for the control system. The dimension of the equation set is reduced to make it solvable based on an assumption that all the on -state resistances of diodes remain equal. In addition, the Kalman filter (KF) is used to improve the stability and accuracy of the calculation results. The calculated results are converted to the normal condition based on the current-voltage ( I–V ) and resistance-temperature ( R–T ) characteristics of SM IGBTs and diodes. The scheme is verified by using the simulation of a five-level three-phase MMC model. The errors of the calculated V CE are within 0.3%, and the calculation accuracy is good enough for the estimation of IGBT degradation. Furthermore, the influences of the measurement accuracy and the equal diode voltage assumption on the calculation accuracy are analyzed. The proposed scheme is expected to be applicable in online condition monitoring of SM IGBTs.

An analytical calculation for lowest forward voltage of PiN diodes

This article reports the lowest forward voltage and its condition for PiN diodes by analytical calculation for the first time. We take account of current balance between conductivity modulation in i‐layer and out flowing diffusion current at the both ends of i‐layer for this estimation, whose accuracy is verified by comparisons with the device simulation results. We employ R (total resistance of PiN diode) × Q (stored carrier in i‐layer) to evaluate the carrier distribution for forward voltage (V), and we confirm that V is minimized at flat carrier distribution. Moreover, we found that V of the flat carrier profile is more minimized to the lowest limit at certain physical properties of the p+ layer and n+ layer at the both ends of the i‐layer. We propose silicon bipolar limit that is trade‐off between blocking voltage and resistance with conductivity modulation as contrasted with the silicon limit for single‐carrier devices. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

The protection from the effects of gamma rays of metal-semiconductor diodes by means of ZnO thin interface layer

In this study, the protective effects of Zinc oxide (ZnO) interfacial layer in the Zn/n-Si rectifying contacts against gamma radiation were investigated. In the fabrication of the diodes, n-type Si is used as a semiconductor. First, an ohmic contact is made by using Au–Sb alloy on the polished surface of the n-Si. Afterwards, the ZnO thin film is grown on the n-type Si semiconductor substrate by the RF magnetron sputtering technique. The structural properties of ZnO thin films are investigated by x-ray diffraction (XRD) measurements. It is found that ZnO films are polycrystalline. Current-voltage (I–V) measurements of Zn/n-Si/Au–Sb and Zn/ZnO/n-Si/Au–Sb diodes which are fabricated under laboratory conditions are taken at room temperature in the dark. The basic electrical parameters such as ideality factor (n), barrier height (Φb), series resistance (Rs), rectifying ratio (RR) and interface state density (Nss) of diodes are calculated from the forward bias I–V characteristics. To examine the effects of gamma radiation on the electrical parameters, the diodes are exposed to gamma rays using barium-133, americium-241, and cobalt-60 gamma sources. After irradiation, I–V measurements of diodes are taken again, the characteristic parameters are calculated and the results are compared with the previous ones.

Ag–Pd–Cu alloy reflector to improve the opto-electrical performance and electromigration resistance of near ultraviolet GaN-based light-emitting diode

We investigated the opto-electrical and electromigration properties of near ultraviolet light emitting diodes (UV-LEDs) fabricated with Ag–Pd–Cu (APC) and Ag only reflectors. It was shown that unlike Ag only sample, the APC sample revealed a smooth surface with hillocks when annealed at 600 °C. The 600 °C-annealed APC sample gave a reflectance of 84.2% at 400 nm, whereas the Ag sample had 69.0%. Both the samples exhibited ohmic behavior when annealed. The specific contact resistivity of the Ag and APC contacts annealed at 500 °C were estimated to be 2.59 × 10−4 and 1.85 × 10−4 Ωcm2, respectively. The X-ray photoemission spectroscopy Ga 2p core level results showed that for the annealed APC sample, the Ga 2p core level was shifted towards the lower binding-energies by 0.67 eV as compared to that of the as-deposited sample. Both UV-LEDs with the 500 °C-annealed Ag and APC reflectors gave the same forward voltage of 3.23 V at 20 mA. The UV-LED with the annealed APC reflector yielded 9.07% higher output at 100 mA than that with the annealed Ag reflector. The APC sample exhibited a longer median-time-to-failure (MTF) by a factor of 1.4 than the Ag sample. The activation energy for the electromigration of these samples was measured to be 0.58–0.7 eV. Electron back scatter diffraction (EBSD) and inverse pole figure (IPF) images revealed that the Ag sample was more <111>-textured than the APC sample. Based on the scanning electron microscopy, EBSD and IPF results, the better thermal and electromigration properties of the APC sample are described and discussed.

Investigating the optical, photosensitivity and photocatalytic properties of double perovskites A2LuTaO6 (A = Ba, Sr): A combined experimental and density functional theory study

Abstract The photophysical properties of double perovskite oxides A2LuTaO6 (ALT; A = Ba, Sr) are investigated to design new photovoltaic materials by exploring the photosensing and photocatalytic properties. The Raman spectra for Ba2LuTaO6 (BLT) and Sr2LuTaO6 (SLT) agree well with the room temperature crystal structures of the materials. The electronic band structure of BLT and SLT show a direct band gap at the Γ-point with the optical excitations occurring between the O p states and the Ta d states. The calculations reveal a comparable visible light absorption coefficient to other well-known ferroelectric perovskite solar cell candidates. In addition, an anisotropy is also developed in the optical properties as the symmetry gets reduced due to the prevalent octahedral distortions. The electrical charge transport, measured under both dark and illuminated conditions, is analyzed in terms of the thermionic emission theory of metal-semiconductor junction. The observed decrease in the Schottky diode resistance (Rs) for all the materials can be correlated to the decrease in the potential barrier upon light illumination. The observed trends in photosensitivity are correlated to the changing symmetry and bond angles. The degradation of organic pollutant rhodamine-B (Rh-B) using BLT and SLT as photocatalysts are shown to possess relatively high degradation rates. The photodegradation kinetics is analysed in terms of the band gap, particle size, dielectric properties and structural changes. This work serves as a model to design new optoelectronic materials by correlating the theoretical electronic and optical properties to the experimentally observed optoelectronic and photocatalytic properties.

The Effect of Metallic Interconnect Spacing on the Thermal Resistance of Flip-Chip Light-Emitting Diodes With Underfill Encapsulation

While highly thermally conductive underfill material has been proposed as a solution for reducing the thermal resistance of flip-chip light-emitting diode (FCLED) packages, studies up until this point have not taken into account the layout of the underlying metallic interconnects and its impact on thermal resistance. This paper provides a deeper investigation into how interconnect spacing affects thermal resistance in conjunction over a range of underfill thermal conductivities. Test vehicles utilizing FCLEDs and copper–tin interconnects were fabricated, tested for thermal resistance, and simulated with ANSYS finite-element analysis software. A follow-up parametric study was performed, in which the effectiveness of increasing underfill thermal conductivity was demonstrated to be highly dependent on the distance between conductive metal interconnects. It was found that when the gap between interconnects is sufficiently small, the thermal conductivity of the underfill plays a negligible role in the overall thermal resistance of the FCLED package. For instance, when the gap is $200~\mu \text{m}$ , an underfill with a relatively high thermal conductivity of 1.0 $\text{W}\cdot \text{m}^{-1}\cdot \text{K}^{-1}$ underfill only reduces thermal resistance ( $\Theta _{\mathrm {JC}}$ ) versus a no-underfill scenario by 2.6% more than does an underfill with a thermal resistance of 0.25 $\text{W}\cdot \text{m}^{-1}\cdot \text{K}^{-1}$ . This effect can be leveraged during package design to allow for unfilled underfill materials to be used, reducing cost and process time.

Effect of Electron Irradiation with an Energy of 0.9 MeV on the I–V Characteristics and Low-Frequency Noise in 4H–SiC pin Diodes

It is established experimentally that noticeable changes in the I–V characteristics and low-frequency noise in 4H-SiC pin diodes irradiated by electrons with an energy of 0.9 MeV are observed after doses of Φ ≥ 1.4 × 1015 cm–2. The currents in the forward and reverse branches of the I–V characteristics vary nonmonotonically at voltages lower than 2 V with increasing dose, which is explained by the interaction between the excited electronic subsystem and metastable defects. In this case, a steady increase in the ideality factor and the series resistance of diodes in the region of exponential growth of the I–V characteristics at voltages exceeding 2 V is observed. The reliable operation of microwave devices with low-noise 4H-SiC pin diodes under conditions of electron irradiation is possible up to a cumulative dose of Φ ≤ 1015 cm–2. In microwave devices, the level of low-frequency noise in which is irrelevant but the stabile regime of parameters is of importance, the dose can be increased to Φ ≈ 8 × 1015 cm–2.

A Universal Approach toward Light-Responsive Two-Dimensional Electronics: Chemically Tailored Hybrid van der Waals Heterostructures

Stimuli-responsive hybrid van der Waals heterostructures (vdWHs), composed of organic molecular switches superimposed on inorganic 2D materials (2DMs), can combine the outstanding physical properties of the latter components with the virtually infinite variety of tunable functionality of molecules, thereby offering an efficient protocol for the development of high-performance multifunctional materials and devices. The use of light as a remote control to modulate the properties of semiconducting 2DMs when interfaced with photochromic molecules suffers from both the limitation associated with the persistent photoconductivity characterizing the 2DMs and the finite thermal stability of the photochromic molecule in its different states. Here, we have devised a universal approach toward the fabrication of optically switchable electronic devices comprising a few nanometers thick azobenzene (AZO) layer physisorbed on 2D semiconductors supported on a trap-free polymer dielectric. The joint effect of the improved 2D/dielectric interface, the molecule's light-modulated dipolar doping, and the high thermal stability of cis-AZO offers the highest control over the reversible and efficient charge carrier tuning in 2D semiconductors with a preserved high performance in 2D field-effect transistors, as quantified in terms of carrier mobility and Ion/ Ioff ratio. The device has the potential to operate as an optical memory with four current levels and long retention time (>15 h). Furthermore, by using a CMOS-compatible micropatterning process, the photoswitchable resistor-diode transition has been achieved on hybrid lateral heterojunction devices. Our approach is of general applicability toward the generation of high-performance hybrid vdWHs for the emergence of functional and responsive devices.