Properties Of Diodes Research Articles

Graphene nanoribbon resonant tunneling diode with dual connection between contacts

In this paper, we numerically study the transport properties of a resonant tunneling diode (RTD) based on graphene nanoribbon (GNR) with an H-type antidote between the contacts. The structure may also be thought of as having two parallel (W-shape) parts connecting the contacts, each having a wider channel region sandwiched between two narrower barrier regions. The energy at which quasi-bound states occur in each part depends on the dimensional parameters of the respective portion in the structure. We study how the transmission through quasi-bound states is influenced by the edge states on the contacts and dimensional parameters such as barrier length and also by the ambient temperature. The results are compared with those of an RTD with a single part connecting the contacts. Transmission peaks at different energies are observed for an RTD with asymmetrical lower and upper parts between the contacts. This is then utilized for the creation of two negative differential resistance (NDR) peaks. For numerical computation, the non-equilibrium Green’s function formalism (NEGF) based on the nearest neighbor tight-binding model is employed.

Effects of hydrogen irradiation on the electrical properties of dilute nitride GaAsN Schottky diodes

Effects of hydrogen irradiation on the electrical properties of dilute nitride GaAsN Schottky diodes

Inhibiting the Appearance of Green Emission in Mixed Lead Halide Perovskite Nanocrystals for Pure Red Emission.

Mixed halide perovskites exhibit promising optoelectronic properties for next-generation light-emitting diodes due to their tunable emission wavelength that covers the entire visible light spectrum. However, these materials suffer from severe phase segregation under continuous illumination, making long-term stability for pure red emission a significant challenge. In this study, we present a comprehensive analysis of the role of halide oxidation in unbalanced ion migration (I/Br) within CsPbI2Br nanocrystals and thin films. We also introduce a new approach using cyclic olefin copolymer (COC) to encapsulate CsPbI2Br perovskite nanocrystals (PNCs), effectively suppressing ion migration by increasing the corresponding activation energy. Compared with that of unencapsulated samples, we observe a substantial reduction in phase separation under intense illumination in PNCs with a COC coating. Our findings show that COC enhances phase stability by passivating uncoordinated surface defects (Pb2+ and I-), increasing the formation energy of halide vacancies, improving the charge carrier lifetime, and reducing the nonradiative recombination density.

Influence of different molar concentration on the structural, optical, electrical and photo diode properties of MoO3 thin films

This article discusses an eco-friendly method for creating metal-insulator-semiconductor (MIS) diodes. MoO3 thin films are prepared at different mole concentrations (0.01, 0.03, 0.05 and 0.07 M) using a Jet Nebulizer Spray Pyrolysis (JNSP) methodology. An orthorhombic phase, which is of special interest because of its potential in electronic applications, was discovered by structural investigation using X-ray diffraction (XRD) in the 0.05 M MoO3 film. Field emission scanning electron microscopy (FE-SEM) pictures of the 0.05 M MoO3 film show a distinct nanoplate shape, indicating positive characteristics for photovoltaic applications. UV–Vis spectroscopy revealed an energy bandgap of 3.21 eV for this concentration. This corresponds to the requisite electronic parameters for a high-performance MIS diode. Then the DC electrical conductivity of the films showed a monotonic rise with the concentration of MoO3, peaking at 0.05 M, suggesting improved carrier transport characteristics. The I–V characteristics of the Cu/MoO3/p-Si diodes revealed that current flows mostly across interfaces and is controlled by carrier concentration. The 0.05 M MoO3 substance exhibited a considerable increase in photocurrent. This work explains the optimized MoO3 concentration and the morphology using the JNSP approach can result in the production of highly efficient MIS diodes suited for a wide range of optoelectronic applications.

Enhancing Blue Polymer Light-Emitting Diode Performance by Optimizing the Layer Thickness and the Insertion of a Hole-Transporting Layer.

Polymer light-emitting diodes (PLEDs) hold immense promise for energy-efficient lighting and full-color display technologies. In particular, blue PLEDs play a pivotal role in achieving color balance and reducing energy consumption. The optimization of layer thickness in these devices is critical for enhancing their efficiency. PLED layer thickness control impacts exciton recombination probability, charge transport efficiency, and optical resonance, influencing light emission properties. However, experimental variations in layer thickness are complex and costly. This study employed simulations to explore the impact of layer thickness variations on the optical and electrical properties of blue light-emitting diodes. Comparing the simulation results with experimental data achieves valuable insights for optimizing the device's performance. Our findings revealed that controlling the insertion of a layer that works as a hole-transporting and electron-blocking layer (EBL) could greatly enhance the performance of PLEDs. In addition, changing the active layer thickness could optimize device performance. The obtained results in this work contribute to the development of advanced PLED technology and organic light-emitting diodes (OLEDs).

Suppression of irradiation effect on electrical properties of silicon diodes by iron in p-silicon

Radiation-hardness of silicon (Si) has been the subject of interest due to the damage of the material-based detectors during and after operation. In this work, the effects of 4 MeV proton-irradiation on the electrical properties of devices fabricated on undoped and Fe-doped p-Si were investigated using current-voltage (I-V) and capacitance-voltage (C-V) techniques. A decrease in current and capacitance is less pronounced and the conduction mechanism remains unchanged on Fe-doped p-Si diode after proton-irradiation. This insignificant change of electrical parameters of the Fe-doped diode after proton-irradiation indicates the suppression of the radiation effect by Fe in Si. The electrical properties of the diode are less dependent on incident radiation, because of the possible prevention of further dislodgement of atoms by incident radiation. As a result, the material becomes resistant to radiation damage, making the electrical properties of the diode independent of incident radiation due to Fe atoms in Si. As a result of the ohmic behaviour displayed by the Fe-doped Si diode, it is possible that in Si, Fe is responsible for generation-recombination (g-r) centres, which are defect levels positioned at the middle of the energy gap of Si. The possibility of these defects being responsible for the suppression of the radiation effect is explained in this work, making Fe a promising dopant to improve the radiation-hardness of Si.

An Investigation of the Diode Properties of a Double Layer of a Combined Gas Discharge

An Investigation of the Diode Properties of a Double Layer of a Combined Gas Discharge

Investigation of Proton Radiation Effect on Indium Gallium Nitride Light Emitting Diodes

This paper investigates the effects of proton radiation on the electrical and optical properties of InGaN light-emitting diodes (LEDs). InGaN LEDs are known for their high brightness and efficiency, making them useful in various applications. However, they are vulnerable to radiation damage, which can degrade their performance over time. In this study, InGaN LEDs were exposed to proton radiation with the fluences of 1 × 1013 cm-2, 3 × 1013 cm-2 and 3 × 1014 cm-2 and their electrical and optical properties were measured before and after irradiation. Results show that proton radiation causes asignificant increase in the reverse leakage current. The light intensity also increases due to radiation. These changes are attributed to radiation-induced defects created in the LED material. The findings of this study provide important insights into the reliability and durability of InGaN LEDs in space and other radiation environments.

Effects of Electron Blocking Layer Thickness on the Electrical and Optical Properties of AlGaN-Based Deep-Ultraviolet Light-Emitting Diode

Effects of Electron Blocking Layer Thickness on the Electrical and Optical Properties of AlGaN-Based Deep-Ultraviolet Light-Emitting Diode

Effect of solder void on mechanical and thermal properties of flip-chip light-emitting diode: Statistical analysis based on finite element modeling

With the increasing demand for highly efficient lighting in the automotive industry, flip-chip light-emitting diodes (LEDs) have become widely used for both interior and exterior lighting. Solder, serving as a crucial interconnecting material, often develops voids during the reflow process, compromising the integrity and reliability of the connections. Thus, understanding the impact of these voids on the mechanical and thermal properties of the product is vital for improving reliability accuracy. This work employs computational methods alongside experimental approaches to address the challenges of replicating solder voids and controlling the solder void fraction. A comprehensive study investigates the effects of solder voids on shearing properties and thermal conductance. Random voids were introduced into the solder pads of an LED assembly within a finite element model (FEM), leading to predictions of maximum shear stress and LED junction temperature. The findings correlate well with the experimental data, validating the FEM's applicability. Furthermore, a statistical analysis was conducted to explore the relationship between solder void fraction, position, and size, aiming to provide objective guidelines for analyzing soldered assembly tomography in reliability assessments.

Role of defects in tailoring the structural, electrical and optical properties of Schottky diodes based on GaAsBi alloy through gamma radiation

This work provides an extensive study of the influence of γ-rays on structural, electrical, and optical characteristics of GaAsBi Schottky diodes fabricated through Molecular Beam Epitaxy (MBE) on GaAs substrates. An important finding is the direct correlation observed between the radiation dose and the consequent increase in the turn-on voltage of the devices. X-ray diffraction (XRD) showed that only phases related to the GaAs and GaAs1-xBix layers were observed. Raman spectroscopy proved to be a powerful tool to elucidate the effects of ionizing radiation on GaAsBi samples. From the results of electrical measurements, such as current density-voltage, the characteristic parameters of the devices improved as a function of the radiation dose. Conversely, the Capacitance-Voltage (C–V) characteristics indicated a rise in the concentration of free carriers in all irradiated samples, suggesting an enhancement in the performance of the diodes. Assessment through Deep Level Transient Spectroscopy (DLTS) further revealed a reduction in the number of electrically active traps following irradiation. Consequently, the findings presented here highlight the potential improvements in diode performance resulting from sample irradiation. Upon subjecting the samples to irradiation doses of 50 kGys and 100 kGys, we identified the presence of three and two electron traps, respectively. This differs from the unirradiated diodes, which displayed four electron traps. Interestingly, the photoluminescence intensity of the main peak exhibited an increment with increasing irradiation dose. This observation implies an enhancement in the optical characteristic, as well as annihilation/contribution of Bi-related traps. These findings corroborate the electrical results obtained in our study. Finally, the Raman results showed that the decrease in the lifetime of the photoexcited carriers leads to a higher recombination rate which in turn leads to a higher photoluminescence (PL) intensity after radiation.

Investigation into the impact of bulk defects in the drift layer on the electrical properties of GaN-based trench Schottky barrier diodes

Using numerical simulation tools, this work systematically investigates the impact of bulk defects in the drift layer on GaN-based trench metal–insulator–semiconductor barrier-controlled Schottky rectifiers. Investigations show that in forward conduction, the acceptor-type defects significantly increase the on-resistance (R on.sp). When the device is in reverse blocking mode, donor-type defects tend to weaken the charge-coupling effect, leading to early breakdown of the device, while acceptor-type defects show the opposite feature. In addition, our report identifies that the reverse blocking effect is significantly impacted when the defects are located in the region with maximum electric field magnitude. We also find that the acceptor-type traps generate a remarkable charging/discharging effect, which will destabilize the dynamic forward conduction process. Hence, we numerically prove that bulk defects should be avoided in actual power diodes.

Facile fabrication and tunable electronic properties of Azure A chloride/Si heterojunction for photoelectrical application

In this study, the fabrication, structural, and photoelectrical properties of AZACl on Si heterojunction (AZACl/Si HJ) were examined. The morphology of the thin film of AZACl was analyzed using SEM, while XRD studied the crystal structure. The UV spectrophotometer displayed three distinct absorption regions at 194, 260, and 605 nm due to their complex chemical structure. The electrical characteristics of the AZACl/Si HJ were investigated in dark circumstances at various temperatures. The J-V technique was used to derive the diode properties of AZACl/Si HJ. The photoelectric properties of the AZACl/Si HJ, such as photocurrent, sensitivity, and responsivity, were estimated. At - 0.5 V and light irradiance equals 100 mW/cm2, the calculated photocurrent equals 4.76 × 10−5 A/cm2, the sensitivity equals 20, and the responsivity equals 476 × 10−4. These results indicated that the fabricated AZACl/Si HJ exhibits photodiode characteristics.

Modulated Crystallization and Carrier Transport Properties for Green Perovskite Light-Emitting Diodes via Thermally Activated Delayed Fluorescent-Modified Hole Transport Layers

Modulated Crystallization and Carrier Transport Properties for Green Perovskite Light-Emitting Diodes via Thermally Activated Delayed Fluorescent-Modified Hole Transport Layers

Enhancing the optical properties of organic fluorine compound-encapsulated AlGaN-based ultraviolet light-emitting diodes with Ni/Au reflective electrodes

The development of AlGaN-based high-efficiency UVC-LEDs capable of effectively eliminating viruses and bacteria is desired. In this study, we demonstrate a significant improvement in optical output power (LOP) by applying optical interference technology and organic fluorine compound packaging technology. Experiments and calculations revealed that an improvement in LED die LOP was achieved through adjusting the optical length to approximately 0.7·λ n, resulting in an amplification of light intensity caused by the interference of light emitted perpendicular to the die. Furthermore, by coating the LED die with an organic fluorine compound and packaging it in a quartz lens, the LOP increased by a factor of 1.5. Ray-tracing analysis showed that, due to optical interference, the LOP of the LED die was more dependent on the light output from the top surface than from the side.

Augmented photovoltaic performance of Cu/Ce-(Sn:Cd)/n-Si Schottky barrier diode utilizing dual-doped Ce-(Sn:Cd) thin films

In the current investigation, we are fabricated the Schottky barrier diode (SBDs) formed on dual doped Ce-(Sn:Cd) (1, 3 and 5 wt%) thin films. The film was prepared by spray pyrolysis of transparent glass and silicon substrates using a low-cost nebulizer, ideal substrate temperature is 450 °C and the structure, optics, morphology & electrical properties of the films were characterized by X-Ray Diffractometer, Atomic Force Microscope and Ultra Violet - Visible spectral, electrical and I–V properties of diodes. All dual doped thin films are the cubic structure, as revealed by the XRD pattern. Then the roughness and smoothness of the film were then revealed by atomic force microscopy (AFM). Ultraviolet–vis spectroscopy is formed on optical absorption and band gap energy (3.91 eV) also electrical conductivity increases Cd concentration of films corresponding activation energy diminish. Current-voltage properties [I–V] and photodiode parameters of Cu/Ce-(Sn:Cd)/n-Si diodes were evaluated in the dark and light. The barrier height (ФB) for the diode fabricated was initiate to be 0.69 eV, as well as ideality factors (n) 2.57 of the diode parameters. As a consequence, the 5 wt% of Cd parade greater device performance for the photodiode applications, the present study is first combination of dual doped samples and low cost JNSP technique.

Effects of the chain length of nonaromatic epoxy resins on thermomechanical and optical properties: experiments, and ab initio and molecular dynamics simulations.

Epoxy resin has been extensively used in the field of advanced electronic materials as an adhesive and encapsulant owing to its excellent material properties. However, recently, there has been a demand for further improvement in heat resistance, high transparency, environmental resistance, and enhanced handling properties for high-brightness light-emitting diodes. Conventional aromatic epoxy resins lack light resistance; therefore, a colorless and transparent epoxy resin without aromatic rings is desirable. In this study, tris(2,3-epoxypropyl) isocyanurate (TEPIC) was used as a nonaromatic epoxy resin, and three types of TEPIC with different side-chain lengths were prepared. The ultraviolet (UV)-visible absorption properties of TEPIC were evaluated using time-dependent density functional theory, and the practicality of the numerical prediction of light resistance was verified. TEPIC yields a UV absorbance spectrum with a lower intensity than those of conventional aromatic epoxy resins, suggesting that TEPIC is expected to have high light resistance. In addition, their thermomechanical properties and the influence of molecular structure were evaluated using both molecular dynamics (MD) simulations and experiments. The MD simulation and experimental results were in good agreement, indicating that the long side chains of TEPIC suppress triaxial deformation-induced failure and improve ductility instead of decreasing strength and stiffness. In addition, the longer side chains form a dense molecular structure with less free volume. These results indicate that numerical approaches can be used to predict various properties of epoxy resins and interpret them from the molecular structure. Accordingly, these approaches can be used to aid the material development process.

A promising yellow-emitting langbeinite-type phosphor NaBaY2(PO4)3:Eu2+ for WLEDs.

The development of novel phosphors with excellent luminescence properties for white light-emitting diodes (WLEDs) is always a formidable task. Compared with the traditional laborious and aimless "trial and error" experiments, a mineral-inspired prototype strategy can provide an efficient and accurate method. Herein, for the first time, a novel yellow-emitting phosphor NaBaY2(PO4)3:Eu2+ was discovered using the mineral-inspired prototype strategy and cation substitution method. The phosphor was prepared via the high-temperature solid-state reaction method, and its crystal structure, luminescence properties and potential application for WLEDs were systematically investigated. The NaBaY2(PO4)3 phase was derived from the K2Mg2(SO4)3-type mineral structure and a photoluminescence study revealed that the phosphor can emit bright yellow light with a maximum at 545 nm upon excitation at 351 nm. A WLED lamp was fabricated by the use of a blend of commercial blue-emitting BaMgAl10O17:Eu2+, yellow-emitting NaBaY2(PO4)3:Eu2+ and red-emitting (Ca, Sr)AlSiN3:Eu2+ phosphors with a 380 nm LED chip. The CIE, CCT, Ra and efficiency of the as-fabricated LEDs were measured to be equal to (0.366, 0.365), 4327 K, 91.2 and 40.8 lm W-1, respectively. These results suggest that NaBaY2(PO4)3:Eu2+ could be a promising candidate for n-UV WLEDs.

Enhancing the charge transport and luminescence properties of ethyl 4-[(E)-(2-hydroxy-4-methoxyphenyl)methyleneamino]benzoate through complexation: a DFT and TD-DFT study.

Organic light emitting diode (OLED) and organic solar cell (OSC) properties of ethyl 4-[(E)-(2-hydroxy-4-methoxyphenyl)methyleneamino]benzoate (EMAB) and its Pt2+, Pd2+, Ni2+, Ir3+, Rh3+, and Zn2+ complexes have been theoretically studied herein. Geometry optimizations have been performed via the r2SCAN-3c composite method while single-point calculations have been carried out at the PBE0-D3(BJ)/def2-TZVP level of theory. Results have shown that complexation with selected metal ions improves hole and electron transfer rates in Pt[EMAB]2 and Rh[EMAB]2 +. Specifically, the hole transport rate of Pt[EMAB]2, (k ct(h) = 6.15 × 1014 s-1), is found to be 44 times greater than that of [EMAB], (k ct(h) = 1.42 × 1013 s-1), whereas electron transport rate of Pt[EMAB]2, (k ct(e) = 4.6 × 1013 s-1) is 4 times that of EMAB (k ct(e) = 1.1 × 1013 s-1). Charge mobility for holes and electrons are equal to 19.182 cm2 V-1 s-1 and 1.431 cm2 V-1 s-1 respectively for Pt[EMAB]2, and equal to 4.11 × 10-1 cm2 V-1 s-1 and 3.43 × 10-1 cm2 V-1 s-1 for EMAB respectively. These results show that, charge transport in EMAB can be tuned for better performance through complexation with transition metals such as Pt2+. OSC properties of the complexes were also studied by comparing their HOMO/LUMO energies with those of (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) and poly(3-hexylthiophene) (P3HT). It turned out that the energy gap of EMAB reduced significantly upon complexation from 2.904 eV to 0.56 eV in [Rh(EMAB)2]+ and to a lesser extent in the other complexes. The energy values of the HOMOs remained higher than those of PCBM while those of the LUMOs were found to be greater than that of P3HT with the exception of [Rh(EMAB)2]+. These findings show that the aforementioned species are good electron donors to PCBM. The open circuit voltage, V OC, of the compounds ranged between 0.705 × 10-19 V and 6.617 × 10-19 V, values that are good enough for practical usage in OSC applications. The UV-visible absorption spectra revealed absorption maxima well below 900 nm in all compounds, vital in the efficient functioning of solar cells. In general, this study has shown that platinoid complexation of EMAB can successfully modify both its OLED and OSC properties, making them better precursors in the electronic industry.

Site occupation, emission color tuning and white LED application of Ce3+-activated chloroborate Ca2BO3Cl

Investigation on Ce3+ ions occupying different cation sites of a specific compound is of great significance for exploring multicolor phosphors. Herein, we report the luminescent properties of Ce3+ in chloroborate Ca2BO3Cl host. Two kinds of Ce3+f-d transitions have been observed via adjusting the doping concentration. The assignment for different Ce3+ sites to certain cation sites is corroborated by structural analysis (XRD), fluorescence spectroscopy (PL) and decay kinetic analysis. Information on the two Ce3+ sites’ wavelengths of the five 5d bands in the Ca2BO3Cl host lattice together with εcfs, ɛc, D and ΔS are obtained. Moreover, with the increasing of Ce3+ doping concentration, the emission peak shows an obviously redshift, and the emission color changes from dark blue to blue. The tuning luminescence properties are attributed to the energy transfer from Ce II to Ce I. The optical properties of the as-fabricated white light-emitting diode (LED) are studied. However, the optical properties of current studied Ce3+ doped Ca2BO3Cl is not good enough to be a candidate for near-UV chip excited phosphor-converted white LED.