Current-voltage Characteristics Research Articles

Study on the effect of Bi/Sr ratio on the device characteristics of high-Tc superconducting terahertz wave emitters made of Bi2Sr2CaCu2O8+δ single crystals

To obtain high-performance THz-wave-emitting devices made of single crystals of Bi2Sr2CaCu2O8+δ (Bi2212), a high-temperature superconductor, an understanding of the device characteristics based on crystal characteristics can be a key issue because, in principle, the electrical properties of the intrinsic Josephson junctions (IJJs) constructed in Bi2212 crystals highly depend on crystal conditions, such as carrier concentration, crystal homogeneities, and crystal defects. To evaluate the tendencies of the device characteristics associated with crystal characteristics, we prepared Bi2212 crystals with different Bi/Sr ratios (x=0.05, 0.15, and 0.25) and δ values (annealed under N2 or O2 gas flow conditions). The unit cell parameter c decreased as the Bi/Sr ratio or δ increased. For the same annealing conditions under N2 gas flow, the superconducting transition temperature as well as the size of the hysteresis loop of the current–voltage characteristics and emission characteristics were significantly suppressed for the sample with x=0.25 compared with the corresponding values for the samples with x=0.05 and 0.15. The experimental results clearly indicate that parameters, such as the Bi/Sr ratio and annealing conditions, are crucial factors in determining the electrical characteristics of a device. This information can be a useful guide for the preparation of crystals for IJJ THz-wave devices that can be fine-tuned according to the desired device characteristics.

Perovskite solar cells: novel modeling approaches for invertible current–voltage characteristics

Perovskite solar cells: novel modeling approaches for invertible current–voltage characteristics

CP-AFM Molecular Tunnel Junctions with Alkyl Backbones Anchored Using Alkynyl and Thiol Groups: Microscopically Different Despite Phenomenological Similarity.

In this paper, we report results on the electronic structure and transport properties of molecular junctions fabricated via conducting probe atomic force microscopy (CP-AFM) using self-assembled monolayers (SAMs) of n-alkyl chains anchored with acetylene groups (CnA; n = 8, 9, 10, and 12) on Ag, Au, and Pt electrodes. We found that the current-voltage (I-V) characteristics of CnA CP-AFM junctions can be very accurately reproduced by the same off-resonant single-level model (orSLM) successfully utilized previously for many other junctions. We demonstrate that important insight into the energy-level alignment can be gained from experimental data of transport (processed via the orSLM) and ultraviolet photoelectron spectroscopy combined with ab initio quantum chemical information based on the many-body outer valence Green's function method. Measured conductance GAg < GAu < GPt is found to follow the same ordering as the metal work function ΦAu < ΦAu < ΦPt, a fact that points toward a transport mediated by an occupied molecular orbital (MO). Still, careful data analysis surprisingly revealed that transport is not dominated by the ubiquitous HOMO but rather by the HOMO-1. This is an important difference from other molecular tunnel junctions with p-type HOMO-mediated conduction investigated in the past, including the alkyl thiols (CnT) to which we refer in view of some similarities. Furthermore, unlike in CnT and other junctions anchored with thiol groups investigated in the past, the AFM tip causes in CnA an additional MO shift, whose independence of size (n) rules out significant image charge effects. Along with the prevalence of the HOMO-1 over the HOMO, the impact of the "second" (tip) electrode on the energy level alignment is another important finding that makes the CnA and CnT junctions different. What ultimately makes CnA unique at the microscopic level is a salient difference never reported previously, namely, that CnA's alkyne functional group gives rise to two energetically close (HOMO and HOMO-1) orbitals. This distinguishes the present CnA from the CnT, whose HOMO stemming from its thiol group is well separated energetically from the other MOs.

Investigation of novel two-dimensional B2CO monolayer and its high sensing performance in detecting nitrogen-containing gases: A combined density functional theory calculation and non-equilibrium Green's function study

Two-dimensional (2D) materials have attracted widespread attention because of their excellent optical and electrical properties and have been extensively studied as gas sensors. A new type of 2D material, the B2CO monolayer, has recently been reported to possess significant structural, energetic, and thermodynamic stability. In this study, density functional theory (DFT) was used to explore the sensing properties of CO, CO2, NH3, NO, and NO2 gas molecules on the B2CO monolayer. After adsorption, the NH3, NO, and NO2 molecules formed chemical bonds with the B2CO monolayer. Among these, the NO2 molecule has the highest muscular adsorption energy in the B2CO monolayer. Based on electronic analysis, the B2CO monolayer can provide robust electron interactions with NO and NO2 molecules. Furthermore, the simulated current–voltage curves showed that the increasing amplitude of the current response for the adsorption of the NO2 molecule is more significant than that for NO. Thus, the calculated sensitivity for the NO2 molecules was much higher than that for the NO molecules in the B2CO monolayer. Based on these results, we predict that the B2CO monolayer will have a much higher sensing performance for detecting nitrogen-containing gases (NCGs) molecules than CO and CO2 molecules, especially NO2 molecules.

All-carbon heterostructures self-assembly during field electron emission from diamond nanotip

In this study we demonstrate formation of all-carbon heterostructures induced by field electron emission from diamond needle-shaped crystallites with nanoscale tips. We show that at certain experimental conditions a carbon nanoprotrusion can be formed at the apex of a diamond emitter. Staircase-like current-voltage curves observed for such emitters indicated the presence of the Coulomb blockade effect in the self-assembled all-carbon heterostructures. The mechanism of nanoprotrusion formation via the field-induced surface diffusion of carbon atoms is revealed by observing the structural transformation of the emitter material using transmission electron microscopy. We also explore how the properties of the formed heterostructures evolve with the field emission current, and show that the characteristic size of the formed nanoprotrusion depends on the dimensions of the diamond nanotip. The developed approach offers a way to reproducible fabrication of heterostructured emitters which can be applied as coherent single-electron sources in vacuum nanoelectronics and electron quantum optics.

Compact Model and Detailed Balance Limit for a Dual n-Type Direct Z-Scheme Heterojunction.

This paper presents a comprehensive study on a compact model and the detailed balance limit for a dual n-type direct Z-scheme heterojunction. The compact model developed in this work describes the current-voltage (IV) characteristics of the staggered heterojunction under one-sided illumination. The model incorporates charge neutrality, surface recombination, thermionic emission over the barrier, and surface potentials. By considering these factors, the IV curve of the staggered heterojunction is captured, shedding light on the charge transfer and separation processes within the device. The heterojunction device consists of two photosystems: photosystem one (PSI) with a wide band gap and photosystem two (PSII) with a narrow band gap. Furthermore, the paper establishes the detailed balance limit for the efficiency of the dual n-type direct Z-scheme heterojunction. The maximum achievable efficiency, estimated to be 11.4%, is determined by the interplay between the band gap of PSII and the empirical relation for the maximum barrier for electrons leaving PSII. This detailed balance limit represents the highest efficiency that can be attained, accounting for carrier generation, recombination, and charge transfer mechanisms. The compact model and the derived detailed balance limit provide insights for designing and improving the performance of direct Z-scheme heterojunctions.

Thermal modeling of perovskite solar cells: Electron and hole transfer layers effects

The thermal behavior of perovskite solar cells (PSCs) can significantly affect their performance, and its investigation leads to a deep understanding of PSCs optimization. In this paper, the electrical and thermal behavior of a PSC is studied. To this end, the optical generation rate is calculated for the standard AM 1.5 solar spectrum and then is applied to calculate the current-voltage characteristics. Examining the efficiency (considering the recombination) for different materials of the electron and hole transfer layers (ETM, HTM, respectively), a structure with better merits is selected. The results revealed that Spiro-OMeTAD as the HTM layer leads to better results than the inorganic one. Hence, the Spiro-OMeTAD-based PSC structures were selected for the thermal modeling section. In the final step, considering the heat generated due to losses (resulting from resistive heating and non-radiative recombination), the thermal behavior of devices is surveyed. The structures with geometrical dimensions of a practical PSC (deposited on a glass substrate with a SiO2 passivation layer) show operating temperatures between 73 °C to 76°C and 80°C to 84.5°C for ZnO and TiO2 as ETMs, respectively. The high heat generated in the perovskite layer can accelerate its undesirable chemical reactions. Surveying the temperature distribution of PSCs can pave the way to study its effects on ion migration and the corrosion of contacts, which are the main drawbacks of such low-cost energy harvesters.

INFLUENCE OF PULSE ELECTROMAGNETIC RADIATION ON PERFORMANCE OF ELECTRIC RADIO PRODUCTS

The subject matter is the processes of analysis of the occurrence of reversible and irreversible failures of semiconductor devices under conditions of exposure to electromagnetic radiation. It is shown that the influence of pulsed electromagnetic radiation is accompanied by the emergence of currents in the conductive elements of products and the emergence of their internal fields. The mechanisms for the occurrence of instabilities of natural oscillations of semiconductor components of electrical and radio products, caused by their interaction with flows of charged particles, have been determined. The presence of instabilities of this kind has a significant impact on the spectral (operating) characteristics of electrical radio products. The results obtained in the work make it possible to assess the degree of influence of pulsed electromagnetic radiation on the operating (volt-ampere) characteristics of electrical radio products. The aim is a model of the mechanisms of the emergence and development of instabilities of natural oscillations of semiconductor structures, components of electrical radio products (communication equipment), in the presence of currents and voltages induced by pulsed electromagnetic radiation. The implementation of such a model is due to the possibility of transforming the energy of a flow of charged particles induced by external electromagnetic radiation into the energy of natural vibrations of a semiconductor structure, taking into account the properties of the structure itself (size, concentration of free carriers, permeability). The transformation of the energy of currents induced by electromagnetic radiation into natural vibrations of a semiconductor structure is determined by two effects (transition or Cherenkov radiation) depending on the location of the structure relative to the direction of the currents. The objectives are: the main electromagnetic effects affecting performance of electrical radio products (ERI) under exposure conditions external pulsed radiation and also indicates characteristic changes ERI parameters that determine their functional purpose, which are a consequence of these effects. The methods used are the method of successive approximations over a small parameter, which allows one to determine the spectrum of natural oscillations of a semiconductor device and the mode of their amplification (instability). The following results are obtained. The results of studies characterizing the malfunction of electrical radio products under conditions of exposure to third-party electromagnetic radiation are presented, as well as the main parameters characterizing the electromagnetic resistance of electronic devices to the effects of pulsed currents and voltages. The characteristic types of malfunctions of semiconductor devices (SCD), components of electronic components, in areas of irreversible and reversible failures, as well as the levels of intensities and currents of electric and magnetic fields affecting the SPD, separating the areas of reversible and irreversible failures, are given. Using the energy approach, a physical model of the occurrence of one of the types of reversible failures of the semiconductor element base (the appearance of S-shaped sections of currentvoltage characteristics) has been developed. This physical model makes it possible to determine the criteria for the electromagnetic resistance of a number of semiconductor devices to the effects of external pulsed radiation and also to obtain calculated ratios for assessing the degree of deviation of the operating characteristics of the PPP from the norm. Conclusion. Development of design relationships that determine the modes of amplification (generation) of oscillations of electrical radio products, making it possible to determine the degree of distortion of their current-voltage characteristics (reversible failures) and complete loss of performance (irreversible failures) depending on the parameters of external electromagnetic radiation. The results obtained in the work can be used in the development of amplifiers, generators and frequency converters operating in the millimeter and submillimeter range that are resistant to external electromagnetic radiation. Quantitative estimates of the criterion for reversible failures (instability increments) show that the amount of radiation energy lies within the sensitivity of modern submillimeter radiation receivers and is the cause of failures.

Study on the Rectification of Ionic Diode Based on Cross-Linked Nanocellulose Bipolar Membranes.

Nanocellulose-based membranes have attracted intense attention in bioelectronic devices due to their low cost, flexibility, biocompatibility, degradability, and sustainability. Herein, we demonstrate a flexible ionic diode using a cross-linked bipolar membrane fabricated from positively and negatively charged cellulose nanofibrils (CNFs). The rectified current originates from the asymmetric charge distribution, which can selectively determine the direction of ion transport inside the bipolar membrane. The mechanism of rectification was demonstrated by electrochemical impedance spectroscopy with voltage biases. The rectifying behavior of this kind of ionic diode was studied by using linear sweep voltammetry to obtain current-voltage characteristics and the time dependence of the current. In addition, the performance of cross-linked CNF diodes was investigated while changing parameters such as the thickness of the bipolar membranes, the scanning voltage range, and the scanning rate. A good long-term stability due to the high density cross-linking of the diode was shown in both current-voltage characteristics and the time dependence of current.

Integrated 2T1C pixel circuit with a-Si TFT and NMOS for active matrix mini-LED displays

The 2T1C pixel driver circuit for mini-LED direct display has been proposed, which separates the switching transistor and the driver transistor from the same display substrate, replaces the driver transistor with n-metal oxide semiconductor (NMOS), and combines printed circuit board substrate and thin-film transistor (TFT) substrate to improve the driving capability of the circuit. The NMOS was soldered with mini-LEDs simultaneously onto a substrate which connects to the a-Si TFT array. Two driving modes for a 32-level gray-scale display panel were investigated to compare the voltage-current and optical characteristics. The results demonstrated that the drain-driving mode is better suited for high brightness and high-power display application scenarios as it supports higher-driven currents, but the source-driving mode is more appropriate for precision gray-scale applications due to the higher current linearity of the mode.

Photovoltaic and resistance switching properties of NiO/Pb0.92La0.08(Zr0.52Ti0.48)O3/LaNiO3

Due to its excellent ferroelectricity and photovoltaic effect (PE), Pb0.92La0.08(Zr0.52Ti0.48)O3 (PLZT) has considerable application potential in the field of multifunctional electronic devices. In this study, an Ag/NiO/PLZT/LaNiO3 structure is prepared on a Si substrate via a combination of sol–gel and pulsed laser deposition methods, and its ferroelectricity, PE and resistance switching (RS) properties are studied in detail. With decrease in temperature, coercive field of PLZT increases, and its residual polarization initially remains constant and then decreases. The results of ultraviolet-irradiation experiments show that the photogenerated open-circuit voltage (Vo) of PLZT first increases slightly and then decreases slightly as the temperature decreases. By changing the direction of PLZT polarization, the polarization field can be oriented in the same direction or opposite to the built-in electric field formed by p–n junction at NiO/PLZT interface. Thus, the total electric field required to drive the photogenerated carriers inside the structure can be tuned, which results in different Vo values. Furthermore, current–voltage characteristics of the structure are tested. It is found that as different polarization charges are generated at the NiO/PLZT interface for different PLZT polarization directions, the holes in NiO can be attracted or repelled by these polarization charges. Thereby, the interface barrier height of the p–n junction can be varied. Consequently, the structure exhibits a pronounced RS effect suitable for multilevel storage applications. These results represent an important experimental basis for the development and application of multifunctional electronic devices for optoelectronics and RS-based memories.

Peculiarities of current transport in boron-doped diamond Schottky diodes with hysteresis in current–voltage characteristics

The paper studies peculiarities of current transport in Au/Pt/Ni/diamond Schottky diodes with the hysteresis in current–voltage (I-V) characteristics and the nonlinear dependence of the barrier height φb on the applied voltage and proposes a method for determining basic parameters. Lateral diode structures were processed on boron-doped HPHT-diamond grown in the Fe-Al-B-C system and demonstrated barrier I-V characteristics with the exponential growth of the forward current of about eight orders of magnitude. It is shown that the voltage-dependent barrier height and hysteresis of the current-voltage characteristics can be explained by the presence of a thin dielectric gap at the metal-semiconductor interface and deep levels with lifetimes of the order of tens of seconds or more. Recharging of deep levels can significantly affect the parameters of the current-voltage characteristics. Three distinct regions were revealed. Excess current at zero voltage (region I) is related to deep-level recharge. Within regions II and III linear dependence of the φb on the applied voltage was observed. A linear dependence of the φb is related to the thermionic-field emission mechanism of current transport. Analysis of the temperature dependence I-V characteristics, capacitance-voltage (С-V) as well as frequency-capacitance (C-f) characteristics of arrays of HPHT diamond Schottky diodes yields information on the distribution of macro-defects, the state of the surface, and doping of the sub-surface region, which can be used for the improvement of the growth process and post-growth treatments for the development of diamond-based microelectronic devices.

СТАТИЧЕСКИЕ ХАРАКТЕРИСТИКИ ДУГИ ПЕРЕМЕННОГО ТОКА С НЕПЛАВЯЩИМСЯ ЭЛЕКТРОДОМ

The paper presents the results of studies of the influence of the parameters of an alternating current arc with a non-consumable electrode on its current-voltage characteristics. It is shown that with increasing duration of pulses of reverse polarity trev, the voltage on the direct polarity decreases monotonically, approaching a value of 3 ... 4.5 V, when trev makes up the predominant part of the period.

Effect of proton radiation on gallium nitride light emitting diodes

The compound semiconductor gallium nitride offers enormous potential for facilitating economic expansion in the silicon-based semiconductor industry, which is currently seeing decreasing performance returns compared to investment costs. Its high electron mobility and electric field strength at the material level have already demonstrated enormous potential for photonics and high-frequency communications applications. However, its application in devices used in the radiation-prone environment is hindered by degradation and failure caused by the radiation. In this paper, the effect of proton radiation on the electrical properties of InGaN light emitting diodes (LEDs) for the fluence range of 1×1014 cm-2 to 3×1014 cm-2 is performed. On comparing the results before and after radiation, it is found that radiation mainly affected the reverse IV characteristics of the device with little or no effect on forward IV or CV characteristics. Apart from the electric properties, the optical properties of the LEDs show improvement after radiation as the light intensity increases post-irradiation.

A Novel Nonisolated Four-Port Converter for Flexible DC Microgrid Operation

In this paper, a new non-isolated four-port DC-DC converter is proposed for DC Microgrid applications. The proposed converter offers a main feature of controlling the DC link voltage regardless of resources availability. By using four IGBT switches and only one diode, three different sources can be interfaced to a boosted DC link load. Different operation modes of the proposed architecture are discussed, testified and validated experimentally. The buck-boost capability of the proposed topology allows an enhanced flexibility to integrate various sources with distinct voltage-current (V-I) characteristics while sharing load power among all ports. In this context, steady state analysis is performed to determine the voltage gains between all ports. The control strategy is developed for the proposed topology to manage power flow between sources and load achieving basic operations for renewable resources such MPPT for PV. A theoretical based study is performed on the proposed converter including steady-state analysis, state-space averaging followed by small signal modeling and frequency response-based controller design. The converter different operating conditions are validated experimentally.

Optimizing Photovoltaic Efficiency Through Di-Indium Tri-Selenide Thin Film Solar Cells

This study focuses on investigating the photovoltaic efficiency of chemically deposited In2Se3 thin films for solar energy conversion. Thin film solar cells have several advantages, including reduced material usage, cost-effectiveness, and the potential for improved efficiency. Our research specifically explores the viability of chemically deposited In2Se3 thin films for converting solar energy into electrical energy through chemical processes. The photovoltaic (PV) cell configuration consists of In2Se3 thin films as the photoanode and a sulfide-polysulphide (0.15 M) solution as the electrolyte. The structure of the cell is n-In2Se3 | NaOH (0.15 M)+ S (0.15 M)+Na2S (0.15 M) |C (graphite). To comprehensively analyze the performance of the thin films, we employ various characterization techniques. These include studying the current-voltage characteristics under both dark and light conditions, capacitance–voltage in the dark, barrier height measurements, power output analysis, photo response evaluation, and spectrum response examinations. Through these analyses, we have discovered that In2Se3 exhibits n-type conductivity. Noteworthy results include a junction ideality factor of 3.43, a flat band potential of −0.680 V, and a barrier height of 0.193 eV. The power output characteristics provide crucial insights into the performance of the PV cell. We measured the open circuit voltage, short circuit current, fill factor, efficiency, and photo response lighted ideality factor, which were found to be 320 mV, 25.4 μA, 36.46%, 0.69%, and 2.56, respectively. This research significantly contributes to our understanding of the photovoltaic efficiency of di-indium tri-selenide thin film solar cells. It offers valuable insights for optimizing their performance in solar energy conversion applications.

Study of bulk damage of high dose gamma irradiated p-type silicon diodes with various resistivities

The bulk damage of p-type silicon detectors caused by high doses of gamma irradiation has been studied. The study was carried out on three types of n+-in-p silicon diodes with comparable geometries but different initial resistivities. This allowed to determine how different initial parameters of studied samples influence radiation-induced changes in the measured characteristics. The diodes were irradiated by a Cobalt-60 gamma source to total ionizing doses ranging from 0.50 up to 8.28 MGy, and annealed for 80 minutes at 60 °C. The Geant4 toolkit for simulation of the passage of particles through matter was used to simulate the deposited energy homogeneity, to verify the equal distribution of total deposited energies through all the layers of irradiated samples, and to calculate the secondary electron spectra in the irradiation box. The main goal of the study was to characterize the gamma-radiation induced displacement damage by measuring current-voltage characteristics (IV), and the evolution of the full depletion voltage (V FD) with the total ionizing dose, by measuring capacitance-voltage characteristics (CV). It has been observed that the bulk leakage current increases linearly with total ionizing dose, and the damage coefficient depends on the initial resistivity of the silicon diode. The effective doping concentration and therefore V FD significantly decreases with increasing total ionizing dose, before starting to increase again at a specific dose. We assume that this decrease is caused by the effect of acceptor removal. Another noteworthy observation of this study is that the IV and CV measurements of the gamma irradiated diodes do not reveal any annealing effect.

Carbon quantum dots boosted resistive switching and magnetic properties in Co3O4-based memory devices

Carbon quantum dots (CQDs) could create opportunities of modulating resistive switching behaviors due to their unique electrical performance. Here, CQDs are introduced to enhance switching uniformity and magnetic properties in Co3O4 thin film memory devices. Compared with the pure Co3O4-based device, the device with CQDs exhibited better performance, such as a reduced initialization voltage, uniform distribution of Set and Reset voltages, stable endurance behavior, and enhanced magnetization performance. The fitting results of current-voltage curves showed that the low-resistance states and high-resistance states of the devices obey Ohmic conduction and Schottky emission, respectively. The improvement in resistive switching properties is ascribed to the formation and rupture of confined conductive filaments due to that CQDs enhanced the local electric field, which can efficiently guide the filament growth and suppress the randomness of filament growth. Magnetization modulation associated with resistive switching involves in the variation of oxygen vacancies concentration and the conversion between Co2+ and Co3+. The present study exhibits an effective path to enhance resistive switching and magnetic properties, which shows promising application to design multifunctional electro-magnetic integrated devices.

SnO-SnO&lt;sub&gt;2&lt;/sub&gt; Nanocomposites Based pn Diode: &lt;i&gt;In Situ&lt;/i&gt; Synthesis, Characterization and Fabrication of Device for pn Diode Applicability

We report on an approach for the in-situ synthesis (chemical method based) of SnO-SnO2 nanocomposites followed by characterisation (including morphological, chemical, structural and optical) and investigation of the electrical properties of the nanocomposites with reference to the as-synthesized SnO2 nanoparticles. Compared to spherical SnO2 particles, the SnO phase is found existing in the form of sheet like morphology. It has been found that through controlling of the Sn:OH precursor ratio is effective for the achievement of SnO phase. Compared to the pristine SnO2 nanoparticles, the current-voltage (I-V) characteristics of the nanocomposites show the p-n junction characteristics. The observation of rectification ratio 2.05 indicates the excellent rectifying property of the nanocomposites due to the presence of p-type SnO phase. Further, exploration of the I-V characteristics has revealed the dominance of space-charge limited current transport mechanism for the nanocomposites sample. The lattice defects are discovered to be the cause of the transport mechanism in the nanocomposites sample.

Hysteresis and Its Correlation to Ionic Defects in Perovskite Solar Cells.

Ion migration has been reported to be one of the main reasons for hysteresis in the current-voltage (J-V) characteristics of perovskite solar cells. We investigate the interplay between ionic conduction and hysteresis types by studying Cs0.05(FA0.83MA0.17)0.95Pb(I0.9Br0.1)3 triple-cation perovskite solar cells through a combination of impedance spectroscopy (IS) and sweep-rate-dependent J-V curves. By comparing polycrystalline devices to single-crystal MAPbI3 devices, we separate two defects, β and γ, both originating from long-range ionic conduction in the bulk. Defect β is associated with a dielectric relaxation, while the migration of γ is influenced by the perovskite/hole transport layer interface. These conduction types are the causes of different types of hysteresis in J-V curves. The accumulation of ionic defects at the transport layer is the dominant cause for observing tunnel-diode-like characteristics in the J-V curves. By comparing devices with interface modifications at the electron and hole transport layers, we discuss the species and polarity of involved defects.