Types Of Diodes Research Articles

Molecular dynamics study of N,N'-di-n-alkyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI)/rubrene interface: Why the charge transfer at the interface is optimized depending on the alkyl chain length of PTCDI.

Molecular dynamics simulations were performed to investigate the interfacial structure of the N,N'-di-n-alkyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI)/rubrene interface, which represents the donor/acceptor interface in new types of organic light-emission diodes. In particular, the interfacial structure was examined for different alkyl chain lengths of PTCDI (Cn-PTCDI) at n = 4, 8, and 13, in order to elucidate the observed maximum charge transfer efficiency at the C8-PTCDI/rubrene interface in a recent experiment. The results revealed that the molecular conformation of the acceptor (Cn-PTCDI) molecules at the interface undergoes changes depending on the alkyl chain length when interacting with the rubrene molecule. It was found that the closest complex between Cn-PTCDI and rubrene is formed at n = 8, consistent with the experimental observation. In addition, the interfacial structures of Cn-PTCDI/air and rubrene/air were examined and compared to gain insights into the inherent stability associated with the intermolecular interactions at the interface.

Ferrocene Chalcone Enhanced Cyclotriphosphazene Photodiode Systems via Click Chemistry: Their Synthesis, Electrical, and Photophysical Properties.

In this study, a new ferrocene-decorated cyclotriphosphazene compound (4) was obtained by the interaction of ferrocene chalcone with azide end groups (2) and spirophosphazene (3) bearing alkyne groups using the click method. The structures of all compounds were confirmed using Fourier transform infrared, 1H, 13C APT, and 31P NMR, and MS techniques. The optical band gaps of compounds were measured, showing values of 4.75 eV for 3, 3.53 eV for 2, and 3.46 eV for final product 4. The optical band gap of compound 4 calculated by density functional theory is 3.28 eV. The electrical properties of the compounds were investigated against the frequency. The results showed that the conduction mechanism is based on the hopping model. New types of diodes were prepared by using compounds 2 and 4. The current-voltage characteristics of the compound 4 diode showed good rectification behavior. The rectification ratio of the heterojunction diode was calculated as 629. The ideality factors were 3.35 for 2 and 7.57 for 4. The barrier heights were 0.68 and 0.92, respectively. Under sunlight (20-100 mW/cm2), both diodes exhibited photodiode properties, with compound 4 being more sensitive to light. This indicates that the diodes can be used in optoelectronic devices due to their photoconductive behavior.

Implementation of Optical Coherent Communication System between Two Computers

This work represents implementation and investigation of optical coherent communication system between two computers. A single mode optical fiber is selected as transmission medium. The data are sent via the RS-232 standard interface with a bit rate of 9.6 kbps from personal computer (PC1) by line receive to convert the data from electrical levels (-12/+12 V) into TTL level (0/5 V). The modulation of this data was accomplished by internal modulation using laser diode type (HFCT-5208M) 1310 nm wavelength. The optical D-coupler was used to combine the optical signal that come from laser source with optical signal of laser local oscillator (OTS-304XI) at 1310/1550 nm wavelength to obtain coherent (homodyne and heterodyne) detection respectively. A PIN photodetector (HFCT-5208M) is used. Calculations of Signal to Noise Ratio (SNR) and Bit Error Rate (BER) for coherent detection were measured at different length of the optical fiber. Result show that high SNR and low BER for heterodyne detection than for homodyne detection.

Spoke-Type Structures in an Ion Diode with Magnetic Insulation of Electrons

The article presents the results concerning the cross-sectional energy density distribution of a pulsed ion beam for two types of diodes with electron open drift: with external magnetic insulation (250 kV, 80 ns, 0.6 T) and with self-magnetic insulation of electrons (250–300 kV, 120 ns, 0.8 T). Anode plasma is formed using a breakdown along the surface of the anode dielectric coating (single-pulse mode) or explosive electron emission (with double opposite-polarity pulses). It was found that, when the energy density of the ion beam exceeds ≈0.4 J/cm2, periodic spoke-type structures with a step of 3–6 cm in the beam cross section are formed. The processes of formation of such a structure—nonuniform density of anode plasma and self-organization of anode and/or cathode plasma in crossed electric and magnetic fields—are analyzed. It is shown that the formation of local plasma regions in the anode–cathode gap of an ion diode can cause the formation of a periodic structure of the cross-sectional energy density distribution.

Characterization of Ba–Sr thin films deposited by spray pyrolysis and fabrication of Ag/Ba–Sr/n-Si/Ag diodes

This study describes the synthesis of barium (Ba) and strontium (Sr) thin films using jet neublizer spray pyrolysis (JNSP) technology, which facilitates the fabrication of junction diodes whose structure, surface morphology, and optical properties are affected by significant water absorption. Ba–Sr films with different strontium concentrations (specifically 0, 2, 4 and 6 wt%) were further investigated to provide a better understanding of how this change affects the final diode type. The research design focuses on fabricating n-type silicon junction diodes containing barium and strontium and directly measuring and analyzing their I–V characteristics, ultimately helping elucidate these devices' electrical behavior. Among the analyzed diodes, the Ag/Ba–Sr/n-Si/Ag diode performed well in various design tests, indicating its competitiveness due to its goodness in optoelectronic devices. The ideal value (n) of a 6 wt% Ba–Sr diode is 1.77 and the barrier height (ΦB) is 0.84 eV. These results demonstrate the general future of Ba–Sr junction diode, as they not only reveal important discoveries regarding their electrical properties but also demonstrate the potential for improved performance in optoelectronic applications.

Ultra-low frequency noise external cavity diode laser systems for quantum applications

We present two distinct ultra-low frequency noise lasers at 729 nm with a fast frequency noise of 30 Hz2/Hz, corresponding to a Lorentzian linewidth of 0.1 kHz. The characteristics of both lasers, which are based on different types of laser diodes, are investigated using experimental and theoretical analysis with a focus on identifying the advantages and disadvantages of each type of system. Specifically, we study the differences and similarities in mode behavior while tuning frequency noise and linewidth reduction. Furthermore, we demonstrate the locking capability of these systems on medium-finesse cavities. The results provide insights into the unique operational characteristics of these ultra-low noise lasers and their potential applications in quantum technology that require high levels of control fidelity.

Frequency reconfigurable slot antenna utilizing solid-state plasma S-PIN diodes: simulation and experimental analysis

This article examines the feasibility of integrating solid-state plasma surface p-i-n (S-PIN) diodes into on-chip slots using silicon-on-insulator technology. Two categories of solid-state plasma S-PIN diodes are characterized. Simulations analyze the current–voltage (I–V) characteristics, carrier concentrations, potential distribution, and thermal considerations of both single and dual S-PIN diodes, with optimization of their structural parameters and sizes. Experimental tests on fabricated S-PIN diodes of varying sizes with bias lines embedded in the on-chip slots show favorable I–V characteristics for both types of diodes. The measured results closely align with simulation predictions for the diodes’ conduction onset voltages. Additionally, a cavity-backed slot antenna is proposed to evaluate and compare radiation characteristics resulting from integrating different types of S-PIN diodes.

Quantum Graphene Asymmetric Devices for Harvesting Electromagnetic Energy.

We present here the fabrication at the wafer level and the electrical performance of two types of graphene diodes: ballistic trapezoidal-shaped graphene diodes and lateral tunneling graphene diodes. In the case of the ballistic trapezoidal-shaped graphene diode, we observe a large DC current of 200 µA at a DC bias voltage of ±2 V and a large voltage responsivity of 2000 v/w, while in the case of the lateral tunneling graphene diodes, we obtain a DC current of 1.5 mA at a DC bias voltage of ±2 V, with a voltage responsivity of 3000 v/w. An extended analysis of the defects produced during the fabrication process and their influences on the graphene diode performance is also presented.

Experimental evaluation of wearable LED strip and side-emitting fiber for optical camera communications systems.

This paper presents an experimental evaluation of two types of light-emitting diode (LED)-based distributed transmitters, namely an LED strip and an LED-coupled side-emitting optical fiber, in both laboratory and wearable optical camera communication (OCC) systems. We study the system performance in terms of success of reception (SoR) with regard to the transmission distance. The best value of SoR is achieved when the camera is facing directly to the transmitter (Tx) from a close distance of 1 m. Additionally, we compare the power consumption, the signal-to-noise ratio performance (SNR) and all the obtained values under optimal conditions are better than the forward error correction (FEC) limit in OCC systems.

Essential oil constituents and secondary metabolites of Mentha viridis under tissue culture technique using violet visible light emitting diodes (LEDs)

This study aimed to propagate the valuable medicinal plant Mentha viridis through in vitro culture of nodal segments measuring approximately 1-1.5 cm. Two different types of light-emitting diode (LED) systems were used to apply three different concentrations of two different cytokinins: 6-benzylaminopurine (BAP) and thidiazuron (TDZ) at 0, 1, or 2 mg/L. The LED systems were white as a control and violet, which is a 1:1 ratio of red and blue light. After a 30-day incubation period, the results revealed significant improvements in the survival rate and the number of shoots per explant across the various treatment groups. With MS medium supplemented with 2 mg/L TDZ and illuminated by white and violet LEDs, the highest values were obtained, yielding survival rates of 93.3% and 13.3 shoots per explant, respectively. Moreover, the treatment involving 2 mg/L TDZ under violet LEDs illumination exhibited superior outcomes in terms of leaf count per explant, callus formation, and callus size. Notably, no callus formation was observed in response to BAP treatments. All treatments resulted in a significant increase in antioxidant enzyme activity and the accumulation of various compounds, such as anthocyanin, ascorbic acid, phenols, flavonoids, peroxidase, and polyphenol oxidase, when compared to the control in a broader context, the levels of IAA, kinetin, and zeatin increased, while GA3 and ABA decreased in response to the applied treatments, as compared to the control. Additionally, ten compounds were consistently found in all treatments by GC/MS analysis of the micro-propagated Mentha, with carvone accounting for the highest proportion (43.5%) and being the predominant component. Among all treatments, nodal segments that were exposed to violet LEDs and grown on MS medium supplemented with 1 mg/L TDZ had the highest carvone content.

Long-term ultraviolet B irradiation at 297 nm with light-emitting diode improves bone health via vitamin D regulation.

Ultraviolet radiation is the primary determinant for vitamin D synthesis. Sunlight is inefficient and poses a risk, particularly for long-term exposure. In this study, we screened the most favorable wavelength for vitamin D synthesis among four types of narrowband light-emitting diodes (LEDs) and then irradiated osteoporosis rats with the optimal wavelength for 3-12 months. The 297 nm narrowband LED was the most efficient. Long-term radiation increased vitamin D levels in all osteoporotic rats and improved bone health. No skin damage was observed during irradiation. Our findings provide an efficient and safe method of vitamin D supplementation.

Voltage and Current Characteristics of Schottky Barrier Diodes and Rectifier Diodes Exposed to Standard Lightning Impulse Voltage

Lightning surges are one of the major reasons of bypass diode (BPD) failure in photovoltaic modules. In this study, standard lightning impulse voltages (SLIVs) were directly applied to Schottky barrier diodes (SKB diodes) and rectifier diodes (PNJ diodes) with different electrical specifications. The critical voltages Vc of SLIV at which the diodes were damaged and the temporal variations of diode current (iD) and voltage (vD) were measured. It was found the iD‐vD characteristics can be categorized into a total of eight patterns: four patterns for the forward SLIV application and the four for the reverse SLIV application, regardless of diode types. The measured results imply that the irreversible voltage dip that occurs before the termination of the reverse breakdown contributes significantly to diode damage in the both forward and reverse SLIV applications. SKB diodes exposed to the reverse SLIV are easily damaged at the lowest magnitude of SLIV among all combinations of diode types and SLIV directions. Once a diode has been damaged due to the first SLIV application, the second application of SLIV to the same diode causes remarkable change in the iD‐vD characteristic even if the magnitude of the second SLIV is smaller than Vc. © 2024 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Emission of Parasitic X Rays of Vacuum-electron Tubes with Glass Housings: Implications for the Evaluation of Occupational Doses.

Despite the large variety of high-voltage semiconductor components for medium and high voltage switching and pulse-forming applications as well as for high-power high-frequency generation, the use of vacuum electron tubes still prevails to a considerable degree. Due to the common design incorporating a high energy electron beam which finally is dumped into an anode or a resonator cavity, these tubes are also considered as sources of X rays produced as bremsstrahlung and characteristic radiation, which are referred to as parasitic X rays. Here three types of vacuum-electron tubes, diode, tetrode, and thyratron, with glass housings are investigated. They are predominantly operated in the high voltage range below 30 kV and are not subject to licensing laws. The measurements of the dose rate and X-ray-spectra were performed in the laboratory without complex electrical circuitry usually used in making practical measurements for occupational radiation protection. For the diode tube, where a parasitic X-ray emission is observed only in the reverse operation as a blocking diode, a broad distribution of dose rates of electrically equivalent specimens was observed. This is attributed to field emission from the electrodes. For the tetrode and the thyratron tubes, field emission from the electrodes is identified as the dominant mechanism for the generation of parasitic X rays. Thus, technical radiation protection must focus on shielding of the glass tube rather than optimization of the electrical circuitry.

Effect of light curing units on color stability and mechanical properties of resin cements after aging

This study aimed to evaluate the color stability, Martens hardness (HMV), and modulus of elasticity (Eit*) of resin cements light-cured using two types of light-emitting diodes (LED) subjected to ultraviolet (UV) aging. Two resin cements were used: light-cured (RelyX Veener) and dual-cured (Variolink II). Forty discs were confectioned for each resin cement (with a diameter of 5 mm and thickness of 1.5 mm). Half of the samples were light-cured by a Radii-cal singlewave and the other half by a Valo® polywave. The specimens were then stored at 37 °C and 100% relative humidity for 24 h to ensure complete polymerization. Baseline evaluations of the color alteration, HMV, and Eit* were performed. The specimens were aged for 252 h in an UV-accelerated aging chamber. Then, a final analysis was performed. Two-way repeated-measures ANOVA was performed on the color changes. Meanwhile, three-way repeated-measures ANOVA followed by Tukey´s test was performed on HMV and Eit* to compare the means (α = 0.05). With regard to the color alteration (ΔE), there was no statistically significant difference between the materials or between the light curing units (p > 0.05). With regard to the mechanical properties, Valo® promoted high values of HMV and Eit* compared with Radii-cal (p < 0.05). With regard to the resin cements, Variolink II showed higher HMV and Eit* values than RelyX Veneer (p < 0.05), except for Eit* after UV aging. The light-curing unit influenced the mechanical properties but not the color stability of the resin cements.

Enhanced structural and optical performance of the novel 3-[(5-amino-1-phenyl-1H-pyrazol-4-yl)carbonyl]-1-ethyl-4-hydroxyquinolin-2(1H)-one heterojunction: experimental and DFT modeling

This study successfully and cost-effectively synthesized a novel compound, 3-[(5-amino-1-phenyl-1H-pyrazol-4-yl)carbonyl]-1-ethyl-4-hydroxyquinolin-2(1H)-one (APPQ, 4), which displayed significant potential for various applications and yielded promising outcomes. Theoretical electronic absorption spectra in different media were acquired using the Coulomb-attenuating approach (CAM-B3LYP) and the Corrected Linear Response Polarizable Continuum Model (CLR) PCM. Employing CAM-B3LYP with the 6-311 + + G(d,p) level of DFT proved to be more accurate than alternative quantum chemical calculation methods, aligning well with the experimental data. Additionally, the CAM-B3LYP method using polarized split-valence 6-311 + + G(d,p) basis sets and CLR PCM in various solvents exhibited good agreement with the observed spectra. The high stability of APPQ, validated by the computed total energy and thermodynamic parameters at the same calculation level, surpassed that of anticipated structure 3. The theoretically calculated chemical shift values (1H and 13C) and vibrational wavenumbers were strongly correlated with the experimental data. The APPQ thin films demonstrated a band gap energy of 2.3 eV through distinctive absorption edge measurement. Photoluminescence spectra exhibited characteristic emission peaks at approximately 580 nm. Current–voltage measurements on n-Si heterojunction devices with APPQ thin films revealed typical diode behavior. These APPQ-based devices showed attractive photovoltaic properties, including an open-circuit voltage of 0.62 V, a short-circuit current of 5.1 × 10–4 A/cm2, and a maximum output power of 0.247 mW/cm2. Overall, the investigated heterojunctions display appealing photophysical characteristics, encouraging advancements in photovoltaics.

INVESTIGATION OF THE INFLUENCE OF SILICON NANOWIRE SYNTHESIS PARAMETERS ON THE CHARACTERISTICS OF PHOTOSENSITIVE SENSORS

Problem. Photosensitive sensors are widely used both in everyday life in climate systems and in communication devices and street lighting. In order to improve the performance parameters of photosensitive sensors, the use of silicon nanowires (SiNWs) has been proposed. A large number of articles are dedicated to the influence of synthesis parameters on the dimensions of SiNWs. However, there is a lack of research on the impact of the surface morphology of SiNW arrays on the electrical and photosensitive parameters of sensors based on them.The purpose of the work The aim of this work is to synthesize silicon nanowires using the metal-assisted chemical etching method, investigate their surface morphology, and fabricate photodiodes based on them to examine the influence of SiNW synthesis parameters on the characteristics of photosensitive sensors, considering the peculiarities of their structure.Research results. Photosensitive sensors of diode type based on SiNWs were synthesized and investigated. The influence of the following synthesis parameters of SiNWs on their lateral and vertical morphology as well as on characteristics of diode sensors based on them was demonstrated: the duration of the first and second stages of metal-assisted chemical etching (MACE), the content of silver nitride and hydrogen peroxide in the solutions of the first and second stages of MACE, as well as surface texturing and processing in isotropic and anisotropic etchants. The maximum operational parameters of the obtained photosensitivity sensors based on the SiNW array were as follows: rectification coefficient of 1320 and photosensitivity coefficient of 3.1 mA/lmV.Conclusions. The obtained results indicate that the technological parameters of the first and second stages of MACE, as well as pre- and post- chemical treatments, have a significant influence on increasing of the surface roughness, height, and porosity of SiNWs, which in turn affect the electric and photosensitive parameters of the sensors. Optimal SiNWs synthesis parameters for achieving of maximum photosensitivity have been established.

ANALYSIS OF THE TECHNOLOGY OF GENERATING MICROWAVE RADIATION WITH THE DEFINITION OF AN ADAPTIVE TYPE OF DIODES FOR THE FURTHER DESIGN OF DEVICES FOR DISINFECTION

The need to find an actual method of decontamination of grain products is more relevant than ever in our time. The needs of agro-producers should be embodied in multifunctional devices that give the opportunity to influence not only the aspect of disinfection, but also would allow to stimulate biological processes. This technique includes the use of ultrahigh-frequency (UHF) radiation. Installations used to solve decontamination issues have one main similar feature, namely the use of diodes in the generation system. Considering the main typical design of the microwave generator, it is possible to observe the main problem of the losses of the useful effect of the generation system - these are the losses in the diodes. For high-quality use and implementation, it is necessary to take into account the quality of processing of grain products, high indicators can be achieved due to the use of radio equipment. Modernization generally occurs by replacing the outdated generating part of the installation with a new one with better technical performance and greater variability of frequency and power ranges. First of all, what this tells us is that each crop has its own radio-physical characteristics, this factor is important for increasing processing efficiency. Studies show that the flexibility and controllability of the plant for agricultural processing is ensured by the use of modernized diodes. The paper examines the main types of diodes used in generating units, describes the main three loss zones, in general and directly in the avalanche diode (Reed diode). During the study of losses, the materials used in semiconductor technology were superficially considered in order to improve the conductivity of the diode. On the basis of the conducted research, reasonable conclusions were made in accordance with the topic of the research. The basic element of the installation is the use of pulse generators, but the use of outdated generators is irrational and pointless. It is clear that the success of this processing method depends on the development of radio technology. Continued efforts in this direction will help preserve and improve the effectiveness of this technology.

Effect of ultraviolet light on field emission performance and lifetime of lateral field emitter devices

Lateral field emission devices have been characterized before and after ultraviolet (UV) light exposure. Two types of planar device structures, diode and bowtie, were studied. These nanoscale devices have 9–15 nm tip-to-tip (bowtie) or tip-to-collector (diode) dimensions with the tips fabricated from Au/Ti. Typical currents of 2–5 nA per tip at 6 V were measured. It was observed that after UV exposure, the collected current was reduced by >28% for the case of a bowtie device; whereas the current was reduced by >39% for the case of a diode device. This reduction can be attributed to water vapor desorption on the dielectric surface between the structures, which in turn reduces surface leakage. The Fowler–Nordheim plot showed a straighter line after UV exposure. After the I-V test, the UV-exposed devices were placed on lifetime tests in a vacuum of <10−8 Torr and were biased at 5 V DC. After 2600 h, an abrupt current decrease was observed: ∼25% for the case of the bowtie and ∼28% for the case of the diode device. Scanning electron microscope images of the bowtie and diode devices showed damage to the tips.

Patterned Coating of Ionic Diode Arrays Toward Flexible Moist‐Electric Generators to Power Wireless Sensor Nodes

AbstractUbiquitous moisture is attractive for developing sustainable mobile power sources. However, how to endow moisture‐electric generators (MEGs) with fine design, mass customization, high power output, and foldability is still a largely unsolved problem. In this work, based on the Patterned Coating method, use is made of modulated carbon nanotube, nano‐Al2O3, and liquid metal inks to design and fabricate MEGs with properties required for their applications. A single MEG of the ionic diode type thus fabricated can generate an open‐circuit voltage (VOC) of 1.03 V and a short‐circuit current density (JSC) of 47.77 µA cm−2. Through large‐area integrated fabrication, an array containing 160 MEGs can generate a VOC of 154.1 V, and an array containing 100 MEGs can produce a short‐circuit current of 1.95 mA. In addition, the excellent wearability of MEG is verified by analyzing its electrical output performance after subjecting it to 800 cycles of bending deformations. The simple and cost‐saving fabrication technology issued from the work opens new perspectives for MEG applications and paves a path to their industrialization. For example, the customizable ionic diode arrays can meet the on‐demand power supply requirements of wireless sensor network nodes in the Internet of Things.

Dependence of diode behaviour and photoresponse of Ga-doped ZnO (GZO)/p-Si junction on the carrier concentration of GZO layer

Ga-doped ZnO (GZO)/p-Si junctions were fabricated by reactive co-sputtering of Zn-GaAs target in Ar–O2 atmosphere. Highly degenerate GZO (carrier concentration ∼1021 cm−3) deposited at 4 % O2 forms non-rectifying contact with p-Si. GZO/p-Si diodes fabricated with moderately doped GZO layers deposited at 5 % O2, having carrier concentration ∼1019 cm−3 display low turn-on voltage (≲ 0.5 V) and ideality factor ≈ 2. Measurement of barrier height by temperature dependent I–V and built-in potential by C–V reveal respective values of (0.74 ± 0.07 eV) and (0.44 ± 0.04 eV), suggesting formation of Schottky type diodes. These diodes display nearly linear I–V characteristics under UV illumination, yielding photoresponsivity ∼1 A/W at ± 1 V. In contrast, GZO/p-Si diodes fabricated with lightly doped (non-degenerate) GZO layers deposited at 6–8 % O2, having carrier concentration ∼1018 cm−3, show higher turn-on voltages (4.5–6.5 V) and ideality factors of 2.5–2.7. I–V and C–V measurements reveal nearly equal values of barrier height and built-in potential, indicating formation of n-p heterojunctions, with near-elimination of conduction band discontinuity. Under UV illumination, I–V characteristics of these GZO/p-Si diodes display non-linear behaviour in forward bias and yield photoresponsivity of ∼0.1 A/W at ±1 V.