Current-voltage Characteristics Of Diodes Research Articles

Voltage Divider based on Switched Capacitors for MEM Generators

Simulation results of the operation of voltage dividers based on switched capacitors with diode and transistor-diode switching for microelectromechanical (MEM) generators are presented. It has been established that for a divider with diode-switched capacitors, the voltage division factor doesn't remain when the load resistance changes, and for higher load resistances, the value of the load voltage asymptotically approaches to V0, but not to V0/N. At the same time, a divider with transistor-diode switching of capacitors at higher load resistances makes it possible to obtain an output voltage Vl, which is N times lower than the voltage of the primary power source V0. Analytical expressions have been obtained for estimating the parameters of dividers with diode switching, which allow calculating the characteristics of the divider at the stage of preliminary design of MEM generators with diode-capacitor voltage dividers. It is shown that the simulation of the operation of a diode-capacitor voltage divider must be carried out taking into account the dynamic current-voltage characteristic of diodes. It is established that when using a bipolar transistor as a charging switch, the ripple coefficient of the output voltage is less than when using a reed relay

THEORY OF THE CURRENT-VOLTAGE CHARACTERISTIC OF A THREE-LAYER SEMICONDUCTOR DIODE UNDER THE ACTION OF AN ELECTRIC FIELD

The current-voltage characteristic of a long three-layer semiconductor diode of the type: p+−n−n+, p+−n−p+, n+−n−n+, etc. has been calculated. Expressions are obtained for the current-voltage characteristic of a three-layer semiconductor structure, the base of which is made of a compensated semiconductor, taking into account the strength of the external electric field. It is shown that due to the presence of zero, minus and plus charged impurities in a compensated semiconductor, the dependence of the concentration of electrons and holes is non-linear. KEY WORDS: current-voltage characteristic, semiconductor structure, electrons and holes.

Physics Based RTD Model Accounting for Space Charge and Phonon Scattering Effects

This paper presents a fully analytical model for the current-voltage (I–V) characteristics of Resonant Tunneling Diodes. Based on Tsu-Esaki formalism, we consider the full electrical potential distribution in the structure, including the space charge regions at the emitter and collector layers. In addition, we account for the scattering suffered by carriers when tunneling through the double-barrier region, as a function of the applied bias voltage. These considerations improve the accuracy of the proposed model when compared with other approaches while keeping it physics based and fully analytical. Finally, the model is validated with experimental and numericaldata, demonstrating its feasibility for applications in circuit simulation environments.

In Situ Visualization and Quantification of Electrical Self‐Heating in Conjugated Polymer Diodes Using Raman Spectroscopy

AbstractSelf‐heating in organic electronics can lead to anomalous electrical performance and even accelerated degradation. However, in the case of disordered organic semiconductors, self‐heating effects are difficult to quantify using electrical techniques alone due to complex transport properties. Therefore, more direct methods are needed to monitor the impact of self‐heating on device performance. Here, self‐heating in poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4H‐cyclopenta [2,1‐b;3,4‐b′] dithiophene)‐alt‐4,7(2,1,3‐benzothiadiazole)] (PCPDTBT) diodes is visualized using Raman spectroscopy, and thermal effects due to self‐heating are quantified by exploiting temperature‐dependent shifts in the polymer vibrational modes. The temperature increases due to self‐heating are quantified by correlating the Raman shifts observed in electrically biased diodes with temperature‐dependent Raman measurements. Temperature elevations up to 75 K are demonstrated in the PCPDTBT diodes at moderate power of about 2.6–3.3 W cm−2. Numerical modeling rationalizes the significant role of Joule and recombination heating on the diode current–voltage characteristics. This work demonstrates a facile approach for in situ monitoring of self‐heating in organic semiconductors for a range of applications, from fundamental transport studies to thermal management in devices.

Four-Scroll Hyperchaotic Attractor in a Five-Dimensional Memristive Wien Bridge Oscillator: Analysis and Digital Electronic Implementation

An electronic implementation of a novel Wien bridge oscillation with antiparallel diodes is proposed in this paper. As a result, we show by using classical nonlinear dynamic tools like bifurcation diagrams, Lyapunov exponent plots, phase portraits, power density spectra graphs, time series, and basin of attraction that the oscillator transition to chaos is operated by intermittency and interior crisis. Some interesting behaviors are found, namely, multistability, hyperchaos, transient chaos, and bursting oscillations. In comparison with some memristor-based oscillators, the plethora of dynamics found in this circuit with current-voltage (i–v) characteristic of diodes mounted in the antiparallel direction represents a major advance in the knowledge of the behavior of this circuit. A suitable microcontroller based design is built to support the numerical findings as these experimental results are in good agreement.

Simulation of forward current-voltage characteristics for Schottky diodes with MOS trenches

Present work is devoted to the development of a mathematical model for the forward current-voltage characteristic of Schottky diodes with a metal – oxide – semiconductor (MOS) trench structure, which takes into account the accumulation of the main carriers in silicon near the walls of the trenches at a forward bias. The proposed model considers the decrease of the series resistance of the Schottky diode drift region with an increase in the voltage at the rectifying contact due to the enrichment of silicon with electrons near the walls of the trenches. The proposed model is compared with the experimental results for Schottky diodes with a metal – oxide – semiconductor trench structure with a nominal reverse voltage of 45.0 V and a nominal forward current of 50.0 A. It is shown that the error in calculating the direct voltage value for the new model does not exceed 1.2 % in the range of direct currents from 20.0 to 50.0 A, which is 4.6–9.7 times less than the calculation error for the classical model. The results obtained can be used to develop the structure and geometry of Schottky diodes with a metal – oxide – semiconductor trench structure with required electrical parameters.

In-Situ Characterisation of Charge Transport in Organic Light-Emitting Diode by Impedance Spectroscopy

The article demonstrates an original, non-destructive technique that could be used to in situ monitor charge transport in organic light-emitting diodes. Impedance spectroscopy was successfully applied to determine an OLED’s charge carrier mobility and average charge density in the hole- and electron-transport layer in a range of applied voltages. The fabricated devices were composed of two commercially available materials: NPB (N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine) and TPBi (2,2′,2″-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)) as hole- and electron-transport layers, respectively. By varying the thicknesses of the hole-transport layer (HTL) and the electron-transport layer (ETL), correlations between layer thickness and both charge carrier mobility and charge density were observed. A possibility of using the revealed dependencies to predict diode current–voltage characteristics in a wide range of applied voltage has been demonstrated. The technique based on a detailed analysis of charge carrier mobilities and densities is useful for choosing the appropriate transport layer thicknesses based on an investigation of a reference set of samples. An important feature of the work is its impact on the development of fundamental research methods that involve AC frequency response analysis by providing essential methodology on data processing.

Forward current transport and noise behavior of GaN Schottky diodes

In this work, we first measure the forward temperature-dependent current-voltage (<i>T</i>-<i>I</i>-<i>V</i>) characteristics of the GaN-based Schottky diodes grown on the bulk GaN substrates, and then study the transport mechanisms of the forward current and the low-frequency current noise behaviors under various injection levels. The results are obtained below. 1) In a forward high-bias region the thermionic emission current dominates, and the extracted barrier height is about 1.25 eV at <i>T</i> = 300 K, which is close to the value measured by capacitance-voltage sweeping. 2) In a forward low-bias region (<i>V</i> < 0.8 V) the current is governed by the trap assist tunneling process, having an ideality factor much larger than 1, and the derived barrier height is about 0.92 eV at <i>T</i> = 300 K, which indicates that the conductive dislocation should be mainly responsible for the excessive leakage current, having a reduced barrier around the core of dislocations. 3) The Lorentzian noise appears only at very small current (<i>I</i> < 1 μA) and low frequency (<i>f</i> < 10 Hz), whose typical time constant is extracted to be about 30 ms, depending on the multiple capture and release process of electrons via defects. 4) At a higher frequency and current, the low-frequency 1/<i>f</i> noise becomes important and the corresponding coefficient is determined to be about 1.1, where the transport is affected by the random fluctuation of the Schottky barrier height.

Determination of temperature dependence of electron effective mass in 4H-SiC from reverse current-voltage characteristics of 4H-SiC Schottky barrier diodes

Determination of temperature dependence of electron effective mass in 4H-SiC from reverse current-voltage characteristics of 4H-SiC Schottky barrier diodes

Effect of Deposition Temperature on the Physical Performance of n-ZnO/p-Si Heterojunction

Comparative study of the physical characteristics of n-ZnO/p-Si heterojunction diode has been done as a function of deposition temperature in the range of 300-600 °C. Transparent conducting (TC) Zinc Oxide (ZnO) thin films were deposited by atmospheric pressure chemical vapor deposition (APCVD) technique on the p-Si(100) and glass substrates. Also, the influences of different deposition temperature on the morphology and optical properties of ZnO films were studied. Both the average surface roughness (from 62.8 to 18.8 nm) and the root mean square (from 78.2 to 24 nm) of ZnO films were decreased with the increase in the deposition temperature. Optical transmittance measurement results exhibited good transparency within the visible wavelength range for the films prepared at a temperature above 400 C. The current-voltage (I-V) characteristics of the heterojunction diodes exhibited rectification behavior and depend on the deposition temperature. The electrical parameters of the n-ZnO/p-Si heterojunctions were also affected by the deposition temperature. The diodes prepared at a temperature above 400 C were possessed lower reverse saturation current and high rectification ratio compared to those fabricated at a relatively lower temperature such as 300 C or 400 °C. Such low a temperature grown n-ZnO/p-Si heterojunction diodes with lower reverse saturation current could be suitable for photo-detection applications.

Improvement of a powerful ion Br - Diode parameters by changing the distribution of the magnetic flux in the anode – cathode gap

The influence of magnetic flux distribution in the anode-cathode gap on the parameters of ion Br – diode was investigated. The distribution of the magnetic field formed by an external power source along the anode and cathodes surfaces of the ion diode was obtained. In addition, the diode current-voltage characteristics were measured by changing the magnetic field induction from 0.4 to 1.5 T. The increase in the magnetic field induction on the anode surface was shown to change the diode operating modes. The difference of the magnetic field value near the surfaces of anode and cathodes was compensated by an increase in the ion current.

Electrical Activity of Extended Defects in Relaxed InxGa1−xAs Hetero-Epitaxial Layers

The electrical activity of extended defects in III–V materials, combining different analysis methods based on lifetime extraction from diode current-voltage characteristics, time resolved photoluminescence (TRPL) and deep level studies using Deep Level Transient Spectroscopy (DLTS) is reviewed. To that purpose p+n junction diodes have been fabricated in In0.53Ga0.47As hetero-epitaxial layers on semi-insulating InP or GaAs substrates. By depositing a strained buffer layer, the Extended Defect Density (EDD) can be varied over several decades, enabling a systematic study of their electrical impact in the same range. The defect densities are determined by High-Resolution X-ray Diffraction (HR-XRD), DLTS and Electron Channeling Contrast (ECCI) techniques. The generation and recombination (GR) lifetimes of the In0.53Ga0.47As layers become dominated by the EDs for densities above about 3 × 107 cm−2, whereby the dominant GR level moves closer to the mid gap position. This is supported by DLTS investigations, showing the occurrence of specific electron traps for defective epi layers, which exhibit a capture behavior that is typical for extended defects.

Optimization of p-type contacts to InGaN-based laser diodes and light emitting diodes grown by plasma assisted molecular beam epitaxy

We investigated the influence of the In0.17Ga0.83N:Mg contact layer grown by plasma assisted molecular beam epitaxy on the resistivity of p-type Ni/Au contacts. We demonstrate that the Schottky barrier width for p-type contact is less than 5 nm. We compare circular transmission line measurements with a p-n diode current-voltage characteristics and show that discrepancies between these two methods can occur if surface quality is deteriorated. It is found that the most efficient contacts to p-type material consist of In0.17Ga0.83N:Mg contact layer with Mg doping level as high as 2 × 1020 cm–3.

Observation and Modeling of Leakage Current in AlGaN Ultraviolet Light Emitting Diodes

Current-voltage ( I-V ) characteristics of AlGaN ultraviolet light-emitting diodes (UV-LEDs) under the temperatures ranging from 50 K to 300 K are analyzed. The abnormal diode characteristics of UV-LEDs below the turn-on voltage indicate the existence of space-charge-limited (SCL) current transport in the presence of deep trap states, which induce a non-linear current leakage effect. The SCL current is gradually overwhelmed by Ohmic leakage as the temperature increases, which is mainly due to the thermally generated carrier concentration and traps deactivation. A modified three-diode circuit model is suggested with an additional series resistor and diode to emulate the forward-bias I-V characteristics of UV-LEDs. An excellent fit to the I-V curves of UV-LEDs is achieved, which illustrates the impact of deep trap states on the electrical characteristics of UV-LEDs.

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.

(Invited) Electrical Activity of Extended Defects in III-V Semiconductors

This paper gives an overview on the electrical activity of extended defects in III-V materials, combining different analysis methods, which are based on lifetime extraction from diode current-voltage characteristics and deep-level studies using Deep-Level Transient Spectroscopy (DLTS). To that purpose p+n junction diodes have been fabricated in In0.53Ga0.47As hetero-epitaxial layers on semi-insulating InP or GaAs substrates. By depositing a strained buffer layer, the Extended Defect Density (EDD) can be varied over several decades, enabling the study of the electrical impact in the same range. It will be shown that the generation and recombination (GR) lifetimes of the In0.53Ga0.47As layers become dominated by the EDs for densities above about 3×106 cm-2, whereby the dominant GR level moves closer to the mid gap position. This is supported by DLTS, showing the occurrence of specific electron traps for defective epi layers, which exhibit a capture behavior which is typical for extended defects.

Unusual behavior of dislocations freshly-introduced under Schottky contact in GaN

The impact of the dislocations introduced by local plastic deformation on the electric properties of low-ohmic n-GaN was investigated. It was found that the freshly introduced dislocations gave rise to increase of the dc leakage current, to changes in frequency dependence and in the shape of current-voltage, ac conductance and capacitance voltage characteristics of stripe-like Au-Schottky diodes. Besides, a rapid recovery of the dislocation-induced changes of the electric properties to their initial state was observed after several hours at room temperature indicating the impact of the presence of depletion region of Schottky diodes on the dynamic properties of freshly introduced dislocations.

Calculation of 4H-SiC Schottky Diode with Breakdown Voltage Up to 3 KV

The current-voltage characteristic of the 4H-SiC Schottky diode for forward and reverse current direction was calculated and simulated on the base of the theory of thermionic emission and a physical analytical model based on the Poisson equation, the diffusive and continuity equations. It is shown that as follows from the theoretical calculations and calculations carried out in ATLAS that breakdown voltage of Schottky diode more than 2 kV is provided at a thickness of 4H-SiC of epitaxial layer from 18 mm. It is established that thickness of epitaxial layer from 20 mm will provide breakdown voltage of Schottky diode more than 2 kV. In addition the current-vltage characteristic for perspective Schottky diode (with breakdown voltage ~3 kV) with thickness of 4H-SiC epitaxial layer of 20 mm, p+ ring of 30 microns wide and five rings of 5 mm wide with a gap width of 2.5 mm, JTE layer of 80 mm wide. It is shown that the diode with the above specified structure can stand breakdown voltage up to ~3 kVÂ

Device for Current Test Pulse Development Through a Diode in a Direct Direction

The article is devoted to the development of a device that allows to generate control current pulses to determine the current-voltage characteristic of diodes in the forward direction. To implement the device, we use NI Digital Electronics FPGA Board, which includes FPGA XC3S500E Xilinx Spartan-3E FPGA and the Linear Technology LTC2624 chip, containing four 12-bit DACs. We consider the creation of a software module via VHDL language that generates 12-bit digital code to create rectangular voltage control pulses with a successively increasing amplitude and transmitted via SPI interface as the part of 32-bit data transfer protocol, using Xilinx WebPACK ISE software.

Temperature Correction of Broadband Power Detectors Based on Low-Barrier Diodes

The article is devoted to investigation of microwave power converter temperature dependence caused by changes in the current-voltage characteristic of diodes. The analytical expressions are given for such diode parameters as junction resistance and diode saturation current that allow to estimate temperature influence on diode detector output voltage. This paper presents a comparison of two methods, i.e. correlation based on a terminological method that works in con-junction with an arithmetic-logical mechanism. The first method implies that the temperature stabilizes by use of identical pair of diodes one of which compensates for temperature-induced changes of the second diode junction resistance. The second method involves formation of correction factors that allow performing temperature correction of measurement results in a wide range of capacities. Based on the conducted temperature tests of microwave power meters with the use of a temperature sensor in the microwave unit, the thermal correction algorithm was implemented. It allows to reduce the changes in the readings from ±15 to ±1.5%. Data from the results of experimental studies that can be used in measuring microwave equipment of various types. The results of experimental studies of detectors based on low-barrier diodes ZB-28 with a boundary speed exceeding 100 GHz and a tangential sensitivity of 1 nW are presented.