Current-voltage Characteristics Research Articles

Refined photovoltaic parameters estimation via an improved Sinh Cosh Optimizer with trigonometric operators

Estimating parameters in solar cell models is crucial for simulating and designing photovoltaic systems. The single-diode, double-diode, and three-diode models represent these systems. Parameter estimation can be viewed as an optimization problem to minimize the difference between measured and estimated data. This study presents PV parameter estimation using the enhanced Sinh Cosh Optimizer (I_SCHO), incorporating trigonometric operators from the Sine Cosine Algorithm (SCA). This integration improves the algorithm’s ability to navigate complex search spaces, avoid local optima, and expedite convergence. Assessment criteria include runtime, convergence behaviour, minimum RMSE, and system reliability measured by SD. Results show that I_SCHO consistently delivers superior accuracy and reliability compared to other methods. Experiments were conducted on five solar cells: RTC France, Photowatt-PWP201, Kyocera KC200GT, Ultra 85-P, and STM6-40/36 module. The study also includes a comparative analysis using state-of-the-art algorithms, demonstrating I_SCHO’s efficiency through RMSE, Power Voltage (P-V) and Current Voltage (I-V) curves.

Study of the Current–Voltage Characteristics of Membrane Systems Using Neural Networks

This article is dedicated to the construction of neural networks for the prediction of the current–voltage characteristic (CVC). CVC is the most important characteristic of the mass transfer process in electro-membrane systems (EMS). CVC is used to evaluate and select the optimal design and effective operating modes of EMS. Each calculation of the CVC at the given values of the input parameters, using developed analytical-numerical models, takes a lot of time, so the CVC is calculated in a limited range of parameter changes. The creation of neural networks allowed for the use of prediction to obtain the CVC for a wider range of input parameter values and much faster, saving computing resources. The regularities of the behavior of CVC for various values of input parameters were revealed. During this work, several different neural network architectures were developed and tested. The best predictive results on test samples are given by the neural network consisting of convolutional and LSTM (Long Short-Term Memory) layers.

Quantum theory of Bloch oscillations in a resistively shunted transmon

A transmon qubit embedded in a high-impedance environment acts in a way dual to a conventional Josephson junction. In analogy to the AC Josephson effect, biasing of the transmon by a direct current leads to the oscillations of voltage across it. These oscillations are known as the Bloch oscillations. We find the Bloch oscillations spectrum, and show that the zero-point fluctuations of charge make it broadband. Despite having a broad-band spectrum, Bloch oscillations can be brought in resonance with an external microwave radiation. The resonances lead to steps in the voltage-current relation, which are dual to the conventional Shapiro steps. We find how the shape of the steps depends on the environment impedance R, parameters of the transmon, and the microwave amplitude. The Bloch oscillations rely on the insulating state of the transmon which is realized at impedances exceeding the Schmid transition point, R > RQ = h/(2e)2.

Ultraviolet Photoresponse and Electroluminescence of Exfoliated Ga2O3 Flake on p-type GaN

Abstract β-phase Ga2O3 (β-Ga2O3) is a promising candidate for deep ultraviolet (UV) solar-blind photodetector due to its large bandgap of 4.9 eV. A high crystal quality two-dimensional β-Ga2O3 flake on p-type GaN (p-GaN) surface was formed using a facile mechanical exfoliation and transfer method, and the heterojunction photodiode consisting of an n-type β-Ga2O3 flake on a p-type GaN substrate was fabricated. The device exhibited a distinctive rectifying current-voltage (I-V) characteristics with a rectification ratio of 4.0×105 at ±2 V. The photodetector responded to both 365 nm and 254 nm UV light irradiation with a photocurrent to dark current ratio of 5.64×10⁵% for 365 nm and 3.38×10⁵% for 254 nm UV. The rise and decay time constants for 365 nm and 254 nm deep UV exposure were obtained through dynamic time-dependent photocurrent measurements. In addition, electroluminescence of the p-type GaN/n-type Ga2O3 heterojunction diode was observed under high forward bias condition.

Infrared photoresponse of GeSiSn p–i–n photodiodes based on quantum dots, quantum wells, pseudomorphic and relaxed layers

Structural and photoelectric properties of p-i-n photodiodes based on GeSiSn/Si multiple quantum dots (QDs) both on Si and silicon-on-insulator substrates were investigated. Elastic strained state of grown films was demonstrated by x-ray diffractometry. Annealing of p-i-n structures before the mesa fabrication can improve the ideality factor of current-voltage characteristics. The lowest dark current density of p-i-n photodiodes based on QDs at the reverse bias of 1 V reaches the value of 0.8 mA cm-2. The cutoff wavelength shifts to the long-wavelength region with the Sn content increase. Maximum cutoff wavelength value is found to be 2.6μm. Moreover, multilayer periodic structures with GeSiSn/Ge quantum wells and GeSiSn relaxed layers on Ge substrates were obtained. Reciprocal space maps were used to study the strained state of GeSiSn layers. The optimal growth parameters were determined to obtain slightly relaxed GeSiSn layers. Designed p-i-n photodiodes based on these structures demonstrated the minimal dark current density of 0.7 mA cm-2and the cutoff wavelength of about 2μm.

Micro‐Engraving UV‐Sensitive Thin‐Film Transistor from Metal–Metal Oxide Nanoparticles with Band‐Gap Engineering

AbstractAs known, n‐type inorganic semiconductor nanoparticles such as zinc oxide nanoparticles have been explored in various sensing applications, which demand high‐density electronic elements placement for rapid operation. Herein, high‐resolution designs of conductive channels of noble metal‐doped zinc oxide nanoparticles is demonstrated using an engraving transfer printing process and silver metal doping approach. Such thin‐film transistors with reduced feature size to 2 µm fabricated exhibited significantly enhanced electron mobility up 3.46 × 10−2 cm2 V−1 s−1 and light sensitivity. Furthermore, the integration of this micropatterning technology and metal doping in thin‐film transistors is utilized for control of current–voltage characteristics under the ultraviolet radiation with high sensitivity. It is suggested that this approach to design of doped inorganic nanoparticle channels paves the way for high‐density thin‐film transistors suitable for optoelectronic circuit, UV photodetectors and neuromorphic computing systems.

Liquid metal ion source based on magnetic suspensions for field emission electric propulsion (FEEP)

This work presents a process for the creation of emitter structures for liquid metal ion sources based on suspensions of iron and nickel in gallium-based room temperature liquid metal alloys. The process does not require needle etching or vacuum wetting of the emitter. Tip radii of less than 3 μm have been achieved. In addition, first measurements and observations from single emitter emission experiments are presented, including current-voltage characteristics, vacuum stability, degradation mechanisms and first thruster characteristics for the use in field emission electric propulsion. The impedance of the magnetic liquid metal emitters was found to correlate with the mass fraction of particles suspended in the liquid metal. Total impedances up to 30 MΩ have been achieved, indicating the feasibility of emitter clustering. Thrust measurements were performed with a commercial of the shelf load cell and verified in a dedicated setup for field emission electric propulsion testing, featuring a sub micro newton counterbalanced double pendulum thrust balance.

Deep traps and persistent photocapacitance in p-SnO2/i-ZrxSn1-xO2/n-SnO2 p-i-n diodes

Deep traps and persistent photocapacitance in p-SnO2/i-ZrxSn1-xO2/n-SnO2 p-i-n diodes

Health indicator construction and health status evaluation for the photovoltaic array based on the current–voltage curve conversion

Health indicator construction and health status evaluation for the photovoltaic array based on the current–voltage curve conversion

High‐Performance and Ultrafast Single Germanium Nanowire Photodetectors

AbstractSemiconductor nanowire‐based photodetectors with high sensitivity and fast photoresponse in the near‐infrared wavelength range are crucial for applications in light‐wave communication switches, as well as environmental and atmospheric sensing. However, to advance this field, it is essential to develop innovative fabrication techniques that improve device performance. Here, the fabrication of an axial p–n junction along single germanium nanowires (Ge NWs) and their photoresponse characterization at near‐infrared wavelengths are reported. The resulting devices exhibit rectifying current–voltage characteristics with a high rectification ratio in dark conditions and operate with high sensitivity at zero bias under illumination. A high responsivity of 1.72 AW−1, a low noise‐equivalent power of 5.68 × 10−11 , and a high‐frequency response with a 3dB cut‐off frequency of 2.85 GHz are determined under 850 nm laser illumination at reverse bias. The high sensitivity of the Ge NW‐based photodetectors is ascribed to the radial built‐in electric field, which increases the carrier lifetime. In addition, the small size of the Ge NWs results in very small capacitance, leading to very fast response. These results have significant potential for advancing high‐speed and low‐power photodetectors in next‐generation optical communication systems and integrated optoelectronic devices.

Tuning resistive switching behavior and conduction mechanism in Se80Te20 alloy with Fe, Co, Ni, and Cu additives

Abstract The present investigations comprehensively analyze the current-voltage characteristics and conduction mechanism in Se80Te20 (ST) and Se78Te20TM2 (STTM; where TM denotes transition metals Cu. Fe, Co, and Ni) glasses. This study focuses on a multi-component system and investigates the voltage-current characteristics of nearly identical disc-shaped specimens at various temperatures below their glass transition points. By analyzing the experimental data, we discovered resistive switching phenomena in the parent glass and its ternary variants containing transition metals Fe, Co, Ni, and Cu. Remarkably, the resistive switching behavior of these samples has been observed to be related to the Meyer-Neldel rule. Additionally, our findings reveal space charge-limited conduction in binary and ternary alloys. We identified linear relationships between ln I and V1/2 across both low and high voltage ranges, which we explained using the Poole-Frenkel mechanism. While the I-V characteristics showed ohmic behavior at lower voltages, a transition to non-ohmic behavior at higher voltages was attributed to voltage-induced temperature effects.

Enhancement of optoelectronic performance by plasmonic effect in TiO2-rGO/Ag-TiO2 based on UV detectors

Abstract In this paper, the plasmonic effect in UV detectors based on titanium dioxide (TiO2) and reduced graphene oxide (rGO) is investigated. The studies have shown that a TiO2-rGO nanocomposite material is obtained by the method of hydrothermal synthesis. The addition of silver nanoparticles (NPs) and Ag- TiO2 core-shell nanostructures (NS) leads to the plasmonic effect and an increase in the optoelectronic parameters is observed. The TiO2-rGO images were obtained with the help of SEM, Raman spectroscopy found the ratio ID/IG. AFM images showed the morphology surface of the rGO. rGO sheets are visible in the SEM and AFM images. Hydrothermal synthesis results in a long-term reduction of rGO, i.e. the amount of oxygen-containing groups decreases. Raman spectroscopy shows the presence of peaks characteristic of the starting materials. The absorption properties when adding plasmonic nanoparticles to the films show changes in the absorption spectrum in the visible region of light, due to the transparency of rGO.
The current-voltage characteristics show that the presence of plasmonic particles in the nanocomposite material leads to an increase in the photoinduced current of about 94 μA, which is almost 3.0 times greater. When irradiated, the multicomponent nanocomposite material with plasmonic nanoparticles responds to light three times faster than TiO2- rGO. The obtained results can be used in the development of new light-sensitive devices for optoelectronic and photocatalytic applications.

Characterization of polymerizable monomers for polymer-sustained-alignment liquid crystal cells with photo-alignment layers

As a model of new-type polymer-sustained-alignment liquid crystal display (PSA-LCD), LC cells having PSA layers formed by mixed monomers of 4,4’-dimethacryloyl-oxy-biphenyl (4,4’-DMABiph) as a main monomer and 4,4’-dimethacryloyl-oxy-benzophenon (4,4’-DMABenz) or 4,4’-dimethacryloyl-oxy-benzil (4,4’-DMABzl) as additional monomers were fabricated on photo-alignment layers, and investigated image sticking characteristics of residual direct current voltage (V rDC) and difference in pretilt angle (Δtilt) before and after application of alternate current voltage. A rate constant of polymerization was increased with the addition of 4,4’-DMABenz or 4,4’-DMABzl, inducing the improvement of the V rDC. The Δtilt was maintained low level even the additional monomers were added, indicating that the level of the image sticking became low. In addition, high voltage holding ratios were maintained under backlight exposure, indicating that long-term stability is also high. Furthermore, new fabrication process of the PSA layer was proposed; the PSA layer was formed by LED-backlight exposure through intermediary of a polarizer by using the mixed monomers of 4,4’-DMABiph and 4,4’-DMABzl.

Development of a fixed-order controller for a robust P&O-MPPT strategy to control poly-crystalline solar PV energy systems

This paper presents a novel approach to modeling and controlling a solar photovoltaic conversion system(SPCS) that operates under real-time weather conditions. The primary contribution is the introduction of an uncertain model, which has not been published before, simulating the SPCS’s actual functioning. The proposed robust control strategy involves two stages: first, modifying the standard Perturb and Observe (P&O) algorithm to generate an optimal reference voltage using real-time measurements of temperature, solar irradiance, and wind speed. This modification leads to determining and linearizing the nonlinear current-voltage (I-V) characteristics of the photovoltaic (PV) array near standard test conditions (STC), resulting in an uncertain equivalent resistance used to synthesize an overall model. In the second stage, a robust fixed-order controller is designed based on this uncertain model, with frequency-domain specifications framed as a weighted-mixed sensitivity problem. The optimal solution provides the controller parameters, ensuring good reference tracking dynamics, noise suppression, and attenuation of model uncertainties. Performance assessments at STC compare the standard and robust P&O-MPPT strategies, demonstrating the proposed method’s superiority in performance and robustness, especially under sudden meteorological changes and varying loads. Experiment results confirm the new control strategy’s effectiveness over the standard approach.

Ultranarrow Semiconductor WS2 Nanoribbon Field-Effect Transistors.

Semiconducting transition metal dichalcogenides (TMDs) have attracted significant attention for their potential to develop high-performance, energy-efficient, and nanoscale electronic devices. Despite notable advancements in scaling down the gate and channel length of TMD field-effect transistors (FETs), the fabrication of sub-30 nm narrow channels and devices with atomic-scale edge control still poses challenges. Here, we demonstrate a crystallography-controlled nanostructuring technique to fabricate ultranarrow tungsten disulfide (WS2) nanoribbons as small as sub-10 nm in width. The WS2 nanoribbon junctions having different widths display diodic current-voltage characteristics, providing a way to create and tune nanoscale device properties by controlling the size of the structures. The transport properties of the nanoribbon FETs are primarily governed by narrow channel effects, where the mobility in the narrow channels is limited by edge scattering. Our findings on nanoribbon devices hold potential for developing future-generation nanometer-scale van der Waals semiconductor-based devices and circuits.

Electrosynthesis of Ru (II)-Polypyridyl Oligomeric Films on ITO Electrode for Two Terminal Non-Volatile Memory Devices and Neuromorphic Computing.

Molecular electronics exhibiting resistive-switching memory features hold great promise for the next generation of digital technology. In this work, electrosynthesis of ruthenium polypyridyl nanoscale oligomeric films is demonstrated on an indium tin oxide (ITO) electrode followed by an ITO top contact deposition yielding large-scale (junction area = 0.7 × 0.7 cm2) two terminal molecular junctions. The molecular junctions exhibit non-volatile resistive switching at a relatively lower operational voltage, ±1V, high ON/OFF electrical current ratio (≈103), low-energy consumption (SET/RESET = 27.94/14400 nJ), good cyclic stability (>300 cycles), and switching speed (SET/RESET = 25ms/20ms). A computational study suggests that accessible frontier molecular orbitals of metal-complex to the Fermi level of ITO electrodes facilitate charge transport at a relatively lower bias followed by a filamentformation. An extensive analysis is performed of the performance of binary neural networks exploiting the current-voltage features of the devices as binary synaptic weights and exploring their potential for neuromorphic logic-in-memory implementation of IMPLICATION (IMPLY) operation which can realize universal gates. The comprehensive analysis indicates that the proposed redox-active complex-based memory device may be a promising candidate for high-density data storage, energy-efficient implementation of neuromorphic networks with software-level accuracy, and logic-in-memory implementations.

New insights into structural, optical, electrical and thermoelectric behavior of Na0.5Bi0.5TiO3 single crystals

The single crystals of lead-free Na0.5Bi0.5TiO3 were grown using the Czochralski method. The energy gaps determined from X-ray photoelectron spectroscopy (XPS) and optical measurements were approximately 2.92 eV. The current-voltage characteristics, depolarization current, dc (σdc) and ac (σac) electrical conductivity, and Seebeck coefficient of the crystals were investigated. The frequency/temperature-dependent electrical properties were also measured and analyzed through complex impedance spectroscopy. An overlapping reversible insulator-metal transition (resistive switching) on nanoscales, caused by the electric field, was detected. Most of these properties were measured for the first time. The activation energy values determined from the conductivity data, the imaginary part of the electric impedance and the modulus indicate that the relaxation process in the high-temperature range is attributable to both single and double ionized oxygen vacancies, in combination with the hopping of electrons between Ti4+ and Ti3+. P-type electrical conductivity was also found. These discoveries create new possibilities of reducing the electrical conductivity of NBT and improving the process of effectively poling this material. Our results indicate the possibility of tuning the material properties by intentionally creating non-stoichiometry/structural defects (oxygen vacancies, cation excess and cation deficiency).

Characterization and analysis of N2 plasma DC glow discharge at different voltage

In this work, the plasma glow discharge characteristics of nitrogen gas will be studied and analyzed at dif-ferent pressures, and we will study the effect of these pressures on the I-V curve, the Panchen curve, the I-P curve, the current-voltage curve, and their effect on the electrical conductivity of the generated plasma. The distance between the glow electrodes was (15.5) cm. The pressures that were used in this work were (0.025, 0.05, 1.5, 5) T. The results indicated that the discharge was operating in the atypical glow region. On the other hand, the discharge current decreased as the gas pressure increased. On the other hand. Also, the con-ductivity decreased in its values with the increase in applied pressure as well as the voltage of the plasma focus.

Boron-Doped Single-Molecule van der Waals Diode.

Single-molecule diode was the first proposed device in molecular electronics. Despite the great efforts and advances over 50 years, the reported rectification ratios, the most critical parameter of a diode, remain moderate for the single-molecule diode. Herein, we report an approach to achieve a larger rectification ratio by adopting the combined strategies of p-type boron doping, the single-layer graphene nodes, and the van der Waals layer-by-layer architecture. Measured current-voltage curves showed one of the as-fabricated single-molecule diodes hit an unprecedented large rectification ratio of 457 at ±1 V. Break junction operations and spectroscopic measurements revealed the three-atom-thick configuration of the single-molecule diodes. With the experimental and theoretical calculation results, we demonstrated the doped boron atoms induced holes to redistribute the electron density, making the asymmetric coupling at positive and negative biases, and the van der Waals interaction promoted asymmetric coupling and significantly boosted diode performance.

Giant Third-Order Nonlinearity Induced by the Quantum Metric Quadrupole in Few-Layer WTe_{2}.

The quantum geometric properties of topological materials underpin many exotic physical phenomena and applications. Quantum nonlinearity has emerged as a powerful probe for revealing these properties. The Berry curvature dipole in nonmagnetic materials and the quantum metric dipole in antiferromagnets have been explored by studying the second-order nonlinear Hall effect. Although the quadrupole moment of the quantum geometric tensor is theoretically predicted to induce higher-order quantum nonlinearity, the quantum metric quadrupole remains experimentally unexplored. Here, we report the quantum metric quadrupole induced third-order nonlinear longitudinal electrical response in few-layer WTe_{2}, persisting up to room temperature. Angle-resolved third-harmonic current-voltage characteristics are found consistent with the intrinsic crystal symmetry of WTe_{2}. Through temperature variation and scaling analysis, we identify the quantum metric quadrupole as the physical origin of the observed third-order longitudinal nonlinearity. Additionally, we determine the angle dependence of the quantum metric quadrupole, establishing third-order nonlinearity as an efficient method for revealing the quantum metric structure.