Trap Distribution Research Articles

Remarkable modification of transferring characteristics for both positive and negative charges in XLPE-PS composite

Insulating materials with excellent performance have been one of the key factors that keep the safe operation of high-voltage direct-current (HVDC) cable systems, and investigating their charge trap distribution characteristics is of great significance to improve electrical properties, such as reducing conductivity, suppressing space charge accumulation, and elevating breakdown strength. In this paper, surface potential decay processes of low-density polyethylene (LDPE), low-density polyethylene/polystyrene (LDPE/PS), crosslinked polyethylene-polystyrene (XLPE-PS) and crosslinked polyethylene (XLPE) were investigated, and migration properties of positive charges and negative charges as well as related charge trap characteristics were analyzed. The results demonstrate that for positive charges and negative charges, the formation of featured structure in XLPE-PS composites reduces carrier mobility and deepens charge trap depth but does not change the width of charge trap energy distribution, which remains 0.27eV. Compared with XLPE, XLPE-PS shows a more unified trap distribution under positive and negative polarity, which may be attributed to the featured structure. The findings are helpful to clarify the relationship between multi-phase structure and electrical insulation performance of XLPE, and to provide a reference for the design of insulating materials for extruded HVDC cables.

Numerical Simulation of Trap Modulated Multi-Mobility Charge Transport Under AC Field

Based on the characteristics of charge distribution under AC electric field with a wide frequency range, this paper focuses on the applicability of the traditional bipolar charge transport model under AC field in oil-impregnated paper (OP) insulation by simulation. Three physical processes of charge injection, migration and trapping/detrapping are discussed. In reaction to the influence of amplitude variation of AC field on injection rate, the charge injection process is described by a concatenation of the Ohmic mechanism and the Schottky mechanism. On account of the correspondence between the frequency and carrier mobility, the single mobility mode is modified to the multi-mobility mode, which exhibits the effect of localized state differences in materials on charge migration. The charge hysteresis under AC field is to do with the trapped charges, so the multi-energy trap distribution model is adopted to reveal the matching relationship between the period of electric field and charge residence time in deep traps. By comparing the simulation results and experimental phenomena, the modified model achieves space charge accumulation under a wide frequency range, and the shape of charge distribution is similar to the experiments, which proves the validity of the model. Further, the simulation results demonstrate that the net charge accumulation decreases with the increase of the electric field frequency, while the total charge accumulation shows an inverse trend with frequency, which is related to the coexistence of positive and negative charges.

High Performance Epoxy Composites Containing Nanofiller Modified by Plasma Bubbles.

The thermal conductivity of polymer materials is a fundamental parameter in the field of high-voltage electrical insulation. When the operating frequency and power for electrical equipment or electronic devices increase significantly, the internal heat will increase dramatically, and the accumulation of heat will further lead to insulation failure and serious damage of the whole system. The addition of filler with high thermal conductivity into polymer is a common solution. However, the interfacial thermal resistance between filler and bulk materials is the major obstacle to improve thermal conductivity. Herein, in order to reduce the interfacial thermal resistance, nanofillers are modified by plasma technology. The surface modification of nano-Al2O3 is carried out using plasma bubbles with three atmospheres (Ar, Ar+O2, air) as well as coupling agent. The situation of surface grafting before and after the modification is characterized using FTIR, XPS, and SEM. The effect of the mechanism of modification on the thermal conductivity and reaction pathway is investigated. The results showed that the thermal conductivity after plasma modification is increased significantly. Especially, the thermal conductivity is increased by 35% for the sample modified by Ar+O2 atmosphere. This results because more hydroxyl is introduced on the filler surface by the plasma bubbles, which enhance the interface compatibility between filler and epoxy. In addition, surface insulation performance for the modified samples also is enhanced by 14%. This is associated with the change of surface resistance and trap distribution. These results provide potential support for the development of fabrication for high performance epoxy composites.

Investigation of charge dynamics in the corona‐aged silicone rubber alumina nanocomposite

AbstractThe effect of corona aging on the surface potential dynamics and charge trap characteristics of silicone rubber alumina nanocomposite are examined using surface potential decay measurement. The aging was carried out by exposing the specimens to corona stress generated by a high‐frequency AC multi needle‐plane electrode system. The results show that the addition of alumina filler increases the surface potential decay time and maximum trap energy. A reduction in trap depth is observed with the corona aging, and the addition of alumina filler limits the degradation and change in charge trap distribution. The results of an analysis of the space charge behavior of different nanocomposites and their comparison are presented. The space charge variation analysis was carried out under the applied electric field of 20 kV/mm at room temperature using the pulsed electro‐acoustic technique (PEA). Based on the results, the charge density, electric field, and charge trap distribution were deduced. It is concluded that the space charge concentration and enhancement in the electric field of the aged material increases with aging duration and it is maximum in the case of 60 min corona‐aged pure silicone rubber. Analysis of the recovery of the charge dynamics of the sample after corona discharges at the different time intervals shows that the recovery of trap distribution is faster for a virgin sample and slower for the sample with 5 wt% of alumina.

General Model for Charge Carriers Transport in Electrolyte‐Gated Transistors

AbstractA charge carrier transport model able to describe the typical modes of operation and some non‐ideal ones from electrolyte‐gated field effect transistors and organic electrochemical transistors (OECTs) is proposed. The analysis include the effect of 2D or 3D percolation transport (PT) and the influence of a shallow exponential trap distribution on the transport. Under these considerations, a non‐constant accumulation layer thickness along the channel can be formed, resulting in a non‐constant effective mobility. The accumulation thickness can depict 2D or 3D PT or even a transition between them. This transition can produce a non‐ideal profile between the linear and saturation regimes in the output curve, region in which a lump appears. Other analyzed phenomenon is the non‐linear behavior for low drain voltage in the output curve, even considering an ohmic contact. This phenomenon is attributed to the traps distribution profile into the semiconductor and the thin accumulation layer thickness close to the injection contact. The conditions when the linear field effect mobility is higher or lower than the saturation one is also analyzed. Finally, electrolyte‐gated organic field effect transistors and OECT experimental data are successfully fitted with this model showing its versatility.

Accessing Deep Traps Distribution in FeS2‐Doped Organic Photovoltaics

Although doping has the potential to improve the performance of organic photovoltaic cells (OPVc), doping effects on charge transport, recombination, and energetic disorder are still obscure. Doping has two opposing effects: on the one hand, dopant ions create more trap centers, while free dopant‐induced charges fill deep states, potentially providing better performance. The optimum amount of dopants can considerably improve the performance of OPVc. Herein, the energetic distribution of trap states in P3HT: PC71BM‐based OPVc doped with iron pyrite nanocubes (NCs) is reported. Using the reverse bias transient photocurrent (TPC) measurement, the energetic trap distributions with different doping conditions are studied. The photovoltaic characteristics and TPC phenomena of the OPVc greatly improve through doping. Variations in trap distributions with doping levels are analyzed to interpret the obtained trap density of states profiles. The light‐dependent current–voltage characteristics help to identify the presence of a less trap‐assisted recombination process in the optimum device. This study highlights the mechanism for performance improvement in devices with optimal doping of iron pyrite NCs.

Investigation of the Temperature Dependence of Volt-Ampere Characteristics of a Thin-Film Si3N4 Memristor

The compatibility of memristor materials with advanced complementary metal-oxide-semiconductor (CMOS) technology is a key factor for microelectronics element base manufacturing. Therefore, we continued studying previously fabricated CMOS-compatible Ni/Si3N4/SiO2/p+-Si samples. We approximated volt-ampere characteristics (VAC) at different temperatures using the general form of the spatial charge-limiting current (SCLC) equation assuming exponential and Gaussian trap distribution within the band gap of Si3N4. Our approximation demonstrated better experimental data matching compared to previous work, where the approximation was based on the uniform trap distribution law. Further, we performed another additional sample measurement set of the samples to evaluate the parameters of the low-resistance state (LRS) variations at different temperatures. Analysis of these measurements allowed us to estimate the temperatures at which the samples will retain LRS for 10 years.

Enhancement in Electrical Properties of Impact Polypropylene Copolymer for Cable Insulation Induced by Rapid Cooling

Impact polypropylene copolymer (IPC) is a promising eco-friendly power cable insulating material with great potential to replace the thermosetting cross-linked polyethylene (XLPE). This article compares the breakdown strength and water tree resistance of IPC and isotactic polypropylene (iPP) after different cooling rates. Unexpectedly, an abnormal enhancement of IPC’s insulating property is discovered. The breakdown strength and water tree resistance of IPC are both increased after rapid cooling, which is opposite to the electrical property deterioration generally found on iPP and XLPE with similar treatment. To reveal the mechanism of abnormal enhancement of IPC, the crystalline structure, phase morphology, and trap distribution are characterized. The results indicate that rapid cooling induces an abnormal increase in the crystallinity of IPC due to the formation of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> crystals, which in turn increases the deep trap level and density and leads to enhanced breakdown strength. Moreover, the formation of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> crystal can also enhance the inter-lamellar coupling and result in higher tensile yield strength, further, decreasing the water tree initiation probability. These results reveal that rapid cooling can significantly regulate the performance of IPC, which should be given serious consideration for the application of IPC in cable insulation.

Cr dopant induced tailoring of intrinsic defects and trap distribution in MgAl2O4 nanocrystals: electron spin resonance and thermoluminescence

Thermoluminescence (TL) response of γ-irradiated Cr3+ doped MgAl2O4 nanocrystals is studied to investigate the impact of dopant ions on intrinsic defects and trap distribution. At low doping concentration, the broad TL glow curve has a dominant incomplete peak attributed to deep F+ centers around 673 K and contribution from shallow , , and trapping states in low temperature region. TL glow curve intensity and trap distribution is found to be influenced with increase in Cr doping concentration. Electron spin resonance spectra show the interaction of electron spins at paramagnetic F+/V− centers with isolated and paired Cr3+ ions with increase in Cr doping concentration. Cr3+ ions doped at octahedral sites are found to be perturbed by the presence of , , etc defect centers and may cause the formation of Cr associated defect clusters at higher doping concentration. A trapping mechanism is proposed as per the TL response obtained upon γ-irradiation to comprehend the intertrap charge transfer among various shallow and deep trapping states.

Fabrication of Reduced Ag Nanoparticle Using Crude Extract of Cinnamon Decorated on ZnO as a Photocatalyst for Hexavalent Chromium Reduction

The crude extract of cinnamon (after abbreviated as KM) was used to produce silver nanoparticles (AgKM). This was subsequently utilized for the hydrothermal production of a composite consisting of AgKM decorated on zinc oxide (AgKM/ZnO) as a photocatalyst for reducing hexavalent chromium (Cr(VI)). Several methods e.g., XRD, SEM, TEM, XPS, PL, and RDB-PAS were used to analyze the optical and physicochemical properties of ZnO/AgKM samples in order to better comprehend the impact of the development of the AgKM-ZnO heterojunction in comparison to pure ZnO. In 60 min, the optimized ZnO/AgKM reduced Cr(VI) by more than 98%, with a rate constant 63 times faster than that of pure ZnO. The enhancement of the separation and transportation of photogenerated electron-hole pairs, as proven by a decrease in photoluminescence intensity when compared with ZnO, was attributed to the composite’s higher Cr(VI) reduction rate. Also, the formation of a new electronic level was created when AgKM are loaded on the surface of ZnO in the composites, as shown by the energy-resolved distribution of the electron trap (ERDT) pattern resulting to enhancement of light absorption ability by narrowing the energy band gap. Thus, ZnO/AgKM composite’s photocatalytic efficacy was enhanced by its narrow energy band gap and reduced charge recombination. Therefore, the newly produced ZnO/AgKM composite can be used as a photocatalyst to purify Cr(VI)-containing wastewater.

Bio-reduced Ag nanoparticle decorated on ZnO for enhancement of photocatalytic reduction of hexavalent chromium and photocatalytic degradation of rhodamine B

Ag nanoparticles reduced by organic components extracted from Jasmine tea leaves were decorated by a hydrothermal reaction on ZnO to fabricate AgNPs@ZnO composite, and then the composite was applied for photocatalytic reactions to degrade rhodamine B (RhB) and reduce hexavalent chromium (Cr(VI)). The produced composite (AgNPs@ZnO) was optically and physicochemically characterized to better understand the impact of the development of the AgNPs-ZnO heterojunction when compared to that of pure ZnO. The optimized AgNPs@ZnO reduced more than 95% of 10 mg/L Cr(VI) in 60 min and degraded more than 95% of 10 mg/L RhB in 180 min, with a rate constant around five times for Cr reduction and three times for RhB degradation faster than that of pure ZnO, due to its superior capacity to separate and transport photogenerated electron-hole pairs, as evidenced by a drop in photoluminescence intensity. Furthermore, when AgNPs were placed on the surface of ZnO in the composites, surface defects were generated on ZnO, as confirmed by the energy-resolved distribution of electron trap (ERDT) pattern for AgNPs@ZnO, indicating the formation of new electron trapping levels. This might cause a reduction of the energy band gap, resulting in the enhancement of light adsorption and reduction of charge recombination. Therefore, the present bio-induced composite of AgNPs@ZnO opens up new possibilities for photochemical purification technology in aquatic environments.

Holistic Optimization of Trap Distribution for Performance/Reliability in 3-D NAND Flash Using Machine Learning

A machine learning (ML) method was used to optimize the trap distribution of the charge trap nitride (CTN) to simultaneously improve its performance/reliability (P/R) characteristics, which are tradeoffs in 3-D NAND flash memories. Using an artificial neural network (ANN), we modeled the relationship between trap distributions and P/R characteristics. The ANN was trained using a large experimentally-calibrated technology computer-aided design (TCAD) simulation dataset. The gradient descent method was adapted to optimize the trap distribution, achieving the best P/R characteristics based on the well-trained ANN. Eventually, we found the best trap profile distributed in both space and energy. In particular, the energetic trap distribution had a larger impact on the P/R characteristics than that of the spatial trap distribution. Furthermore, in terms of the P/R characteristics, it was generally preferable to increase all inputs of the energetic trap distribution. However, the acceptor-like trap energy level ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E_{TA}$ </tex-math></inline-formula> ) and its standard deviation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma _{EA}$ </tex-math></inline-formula> ) caused a tradeoff between P/R characteristics; therefore, ML was used to determine their optimal points. The proposed ML method allows the optimization of trap distribution to obtain the best P/R characteristics rapidly and quantitatively. Our findings could be used as a guideline for determining the physical properties of CTN in 3-D NAND flash cells.

Multicolor and multimode luminescence regulation and anti-counterfeiting application of lanthanide ions doped Li&lt;sub&gt;0.9&lt;/sub&gt;K&lt;sub&gt;0.1&lt;/sub&gt;NbO&lt;sub&gt;3&lt;/sub&gt; phosphors

Multicolor and multimode luminescence materials have important applications in the field of information security encryption. However, the design and synthesis of multicolor multimode luminescent materials is still a challenge, and only several materials have been reported. In this paper, a series of single doped and double doped Li&lt;sub&gt;1–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;K&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;NbO&lt;sub&gt;3&lt;/sub&gt;:Pr&lt;sup&gt;3+&lt;/sup&gt;/Er&lt;sup&gt;3+&lt;/sup&gt;/Tm&lt;sup&gt;3+&lt;/sup&gt; phosphors are prepared by high temperature solid state method. The structure, morphology, optical properties and thermoluminescence (TL) spectra are characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), luminescence spectrometer and self-made heating device. Firstly, the effects of different values of K&lt;sup&gt;+&lt;/sup&gt; content on the luminescence and trap distribution of LiNbO&lt;sub&gt;3&lt;/sub&gt; materials are studied. The results show that the ionic lattice is distorted when a small quantity of K&lt;sup&gt;+&lt;/sup&gt; ions replace Li&lt;sup&gt;+&lt;/sup&gt;. With the addition of K&lt;sup&gt;+&lt;/sup&gt;, the photoluminescence excitation (PLE) spectra monitored emission of 620 nm shows that the ratios of the absorption peaks from matrix (200–310 nm) to absorption peaks from the intrinsic transition of Pr&lt;sup&gt;3+&lt;/sup&gt; ions 4f→5d (310–430 nm) change significantly, showing a double-peak characteristic. When the concentration of K&lt;sup&gt;+&lt;/sup&gt; ions is 0.5, the absorption peak from the matrix disappears, which may be due to the phase transition of the matrix lattice caused by excessive K&lt;sup&gt;+&lt;/sup&gt; ions or the introduction of a large number of defect energy levels into the matrix lattice. Moreover, K&lt;sup&gt;+&lt;/sup&gt; ion doping can regulate the density and distribution of traps. TL curves show that a small quantity of K&lt;sup&gt;+&lt;/sup&gt; doping increases the trap density of shallow traps. When a large quantity of K&lt;sup&gt;+&lt;/sup&gt; is doped, the phase changes of matrix lattice and the defect density decrease. Secondly, the doping of Li&lt;sub&gt;0.9&lt;/sub&gt;K&lt;sub&gt;0.1&lt;/sub&gt;NbO&lt;sub&gt;3&lt;/sub&gt; matrix by different luminescent centers (Pr&lt;sup&gt;3+&lt;/sup&gt;/Er&lt;sup&gt;3+&lt;/sup&gt;/Tm&lt;sup&gt;3+&lt;/sup&gt;) is studied. The results show that the multicolor luminescence emission in red, blue and green bands and the tunable multimode luminescence (up/down conversion luminescence, afterglow luminescence and photo-stimulated luminescence) are realized by the selective excitation. According to the multicolor and multimode characteristics of the phosphors, a butterfly-shaped anti-counterfeiting pattern is designed. Owing to the different energy level positions of the luminescence centers, dynamic multicolor photoluminescence is realized by selective excitation at different wavelengths. Based on the upconversion luminescence characteristics of Er&lt;sup&gt;3+&lt;/sup&gt; and the excellent afterglow characteristics of Pr&lt;sup&gt;3+&lt;/sup&gt; in Li&lt;sub&gt;0.9&lt;/sub&gt;K&lt;sub&gt;0.1&lt;/sub&gt;NbO&lt;sub&gt;3&lt;/sub&gt; material, the designed anti-counterfeiting pattern shows the dynamic color change and multicolor, multimode high-order anti-counterfeiting application.

Research on the surface structure engineering of boron nitride nanotubes and mechanism of their regulation on the properties of epoxy composite dielectric

Adding nanofillers to epoxy resin matrices is a common approach to achieve their multi-function, among which boron nitride nanotubes (BNNTs) with one-dimensional nanostructures have attracted much attention because of their ultra-high thermal conductivity, wide energy level band gap, high aspect ratio and mechanical strength. Yet, the strong π-π non-covalent bonding and lip-lip interactions make BNNTs prone to agglomeration in the epoxy resin matrix. Moreover, the different physicochemical properties of BNNTs and epoxy resins as well as the chemical inertness of BNNTs surface lead to the lack of effective interfacial interaction between BNNTs and epoxy resin matrix. Therefore, the performance of the epoxy composite dielectric is not enhanced by simple blending solely, but will even have the opposite effect. To address the problems of BNNTs, in this article, the surface structure of BNNTs was constructed from the perspective of interface modulation by using sol-gel method to coat mesoporous silica (mSiO&lt;sub&gt;2&lt;/sub&gt;) on BNNTs surface and further introducing silane coupling agent (KH560). The results indicate that constructing the surface structure of BNNTs can optimize the level of interfacial interaction between BNNTs and epoxy resin matrix, which results in stronger interfacial connection and elimination of internal pore phenomenon. The dielectric constant and loss of the composite dielectric prepared in this way were further reduced, reaching 4.1 and 0.005 respectively at power frequency, which was significantly lower than that of pure epoxy resin. At the same time, the mechanical toughness (3.01 MJ/m&lt;sup&gt;3&lt;/sup&gt;) and thermal conductivity (0.34 W/(m·K)) were greatly improved compared with pure epoxy resin. In addition, the unique nano-mesoporous structure of mSiO&lt;sub&gt;2&lt;/sub&gt; endowed the composite dielectric with a large number of deep traps, which effectively hinders the migration of electrons, thereby improving the electrical strength of the composite dielectric, and the breakdown field strength reached 95.42 kV/mm. Further, Tanaka multinuclear model was used to systematically investigate the interfacial mechanism of BNNTs surface structure construct on dielectric relaxation and trap distribution of composite dielectrics. The above results indicated that the good interfacial interaction between BNNTs and epoxy resin matrix was crucial for the establishment of the micro-interface structure and the improvement of macroscopic properties of composite dielectrics. This paper offered a novel idea for the multifunctionalities of epoxy resin, and also provided some experimental data support for revealing the correlation between surface properties of nano-fillers, microstructure of composite dielectric and macroscopic properties.

Effect of radical scavenger on electrical tree in cross‐linked polyethylene with large harmonic superimposed DC voltage

AbstractIn this study, three kinds of radical scavenger Chimassorb 944, Tinuvin 622, and Tinuvin 770 are used to suppress the growth of electrical trees in cross‐linked polyethylene (XLPE) with transient superimposed voltage under the temperature gradient. The tree morphology, tree length, accumulated damage, and time to breakdown are used to investigate the effect of radical scavenger on the electrical treeing process. It is found that under the temperature gradient caused by the temperature rise on the high voltage side, only Tinuvin 622 can always suppress the electrical tree as the temperature gradient rises. Under the temperature gradient caused by the temperature rise on the ground side, the three radical scavengers can all suppress the electrical tree. The breakdown of electrical tree exhibits the strong DC polarity dependence. Meanwhile, energy levels of these three radical scavengers are calculated through quantum chemistry, and the results indicate that radical scavengers have greater electron affinity, smaller ionisation energy, and smaller energy gap than XLPE. According to the surface potential decay test results at 60°C, it is found that all three radical scavengers can introduce deep traps. The different performances of radical scavengers under different temperature gradients and voltages are determined by the trap distribution characteristics, the molecular structure and chemical reaction of the additives themselves. It is concluded that Tinuvin 622 has potential for use in high voltage direct current XLPE cable application.

Achieving Persistent Luminescence Performance Based on the Cation-Tunable Trap Distribution.

Deep-red persistent luminescence (PersL) materials have promising applications in fluorescence labeling and tracking. PersL spectral range and PersL duration are considered to be the key factors driving the development of high-performance deep-red PersL materials. To address these two key issues, the performance of PersL materials was continually optimized by doping with cations (Si4+ and Al3+ ions), relying on the material of Li2ZnGe3O8:Cr3+ from the previous work of our group, and a 4.8-fold increase in PersL radiation spectrum intensity and more than twice the PersL duration was achieved (PersL duration up to 47 h). Ultimately, the obtained PersL materials are used to demonstrate their potential use in multi-level anti-counterfeiting, tracking and localization, respectively. This study provides a unique and novel entry point for achieving high-performance PersL materials by optimizing the PersL material host to modulate the electronic structure.

Effects of Ion Beam Treatment on DC Flashover Characteristics of Epoxy

The effect of ion beam treatment on surface flashover characteristics of epoxy is evaluated and explored. Epoxy samples are prepared and ion beam treatment is carried out for 10-, 15-, 20-, 25-, and 30-min durations using an end-Hall ion source. Flashover test of both pristine and treated samples is conducted at negative dc voltage in air. The results indicate the effectiveness of ion beam treatment to enhance the flashover properties of epoxy. The flashover voltage of the epoxy resin increased to 21.35% after ion beam treatment for a duration of 20 min. Optical microscopic images, scanning electron microscopy (SEM) images, and results from Fourier transform infrared spectroscopy reveal the change in physicochemical characteristics of epoxy resin after treatment. The obtained surface potential from the surface potential decay (SPD) test shows a faster decay rate of surface charges for treated samples than the pristine epoxy. Moreover, from the trap distribution characteristics, it is found that ion beam treatment reduces the surface trap depth, which increases the surface conductivity of the epoxy insulator and helps to promote the charge migration and transport along the insulator surface.

Electrical Noise Analysis of Z Shape Horizontal Pocket and Hetero Stack TFETs under Trap Distribution

In this work, a comprehensive investigation on noise analysis for two different low power devices, namely Z-shaped Horizontal Pocket (ZHP) and Hetero Stack (HS) TFETs, is presented within low to high frequency range. The simulation is performed for these structures in the presence of Uniform and Gaussian trap distributions at the interface of Silicon and oxide materials for three different noise namely Flicker noise, Generation Recombination (GR) noise, and Diffusion noise with the help of the Sentaurus TCAD simulator. The result reveals that Flicker and GR noise are dominates at Low Frequency, while, the diffusion noise reports significant influence at the high-frequency range. Finally, a comparative analysis has been done in terms of noise current spectral density (Sid) of the considered structures with the existing literature.

Highly Sensitive Dual‐Band Switchable between Ultraviolet and Visible Region Photomultiplication Type Polymer Photodetectors

AbstractDual‐band photomultiplication type polymer photodetectors (PM‐PPDs) are achieved with the structure of ITO/PDIN/poly[N,N′‐bis(4‐butylphenyl)‐N,N′‐bis(phenyl)benzidine] (poly‐TPD):2,2′‐((2Z,2′Z‐(12,13‐bis(2‐ethylhexyl)‐3,9‐diundecyl‐12,13‐dihydro‐[1,2,5]thiadiazolo[3,4‐e]thieno[2′′,3′′:4′,5′]thieno‐[2′,3′:4,5] pyrrolo‐[3,2‐g]thieno[2′,3′:4,5]thieno[3,2‐b]indole‐2,10‐diyl)bis‐(methanylylidene)) bis‐(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))‐dimalononitrile (Y6) (100:2, wt/wt)/MoO3/poly(3‐hexylthiophene) (P3HT):[6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) (100:2, wt/wt)/Al. Electron traps can be formed with Y6 surrounded by poly‐TPD or with PC71BM surrounded by P3HT. Trapped electrons near ITO/PDIN or Al electrode can assist hole tunneling injectionunder forward or reverse bias, respectively. The dual‐band PM‐PPDs exhibit ultraviolet spectral response under forward bias dependent on trapped electron distribution near ITO/PDIN electrode, while presenting visible spectral response under reverse bias determined by trapped electron distribution near Al electrode. The performance of dual‐band PM‐PPDs can be optimized by decreasing P3HT:PC71BM layer thickness. The optimal dual‐band PM‐PPDs exhibit external quantum efficiency (EQE) of 2800% at 350 nm under +10 V bias with full‐width at half‐maximum of 80 nm, while achieving EQE of 7500% at 430 nm under −10 V bias. The EQE values of optimal dual‐band PM‐PPDs are markedly improved by raising bias, reaching 13 000% at 350 nm under +16 V bias and 27 000% at 430 nm under −16 V bias. This work provides an effective method to prepare dual‐band PM‐PPDs by manipulating the interfacial trapped electron distribution.

Integrated fluid inclusion studies and source rock parameters in constraining hydrocarbon potential in offshore Lamu Basin, Kenya

Fluid inclusion signal strength and visual inclusion abundance are generally lower along migration pathways than in charged reservoirs from the same area. A zone that displays strong fluid inclusion stratigraphy (FIS) hydrocarbon indications and high visualized petroleum inclusion abundance, indicates paleo-charge or in some cases a migration pathway, e.g, where inclusion abundance is enhanced by extensive microfracturing. In this study, fluid inclusion data are interpreted in seven offshore wells of the Lamu Basin to enhance the understanding of hydrocarbon generation, migration and migration pathways. The study also examines the interrelationship among rock texture, rock composition and trapped fluid distribution in the study area. The studies were based on FIS analyzed data courtesy of Fluid Inclusion Technologies (FIT) Inc. in USA laboratories. FIT conducted analysis on 391 samples from the Paleocene to Upper Jurassic (Kiboko-1 well), 249 from the Paleoecene to Campanian (Kubwa-1 well), 106 from the Maastrichtian to Turonian (Mbawa-1 well), 59 from the Eocene to Campanian (Pomboo-1 well), 26 form the Lower Eocene to Maastrichtian (Simba-1 well), 16 from the Eocene to Maastrichtian (Kipini-1 well) and 11 from the Maastrichtian to Campanian (Kofia-1 well). It also made analysis on sidewall core sample plates, with 44 from the Maastrichtian to Campanian (Kubwa-1 well), 108 from the Campanian to Upper Jurassic (Kiboko-1 well) and 8 from the Campanian (Pomboo-1 well) for petrographic evaluation. For photomicroscopy, thin sections were examined under a petrographic microscope using Ultra Violet (UV) fluorescence and microthermometry, in order to verify the presence of petroleum bearing inclusions in the rock samples and to explore textural relationships that may yield additional information on the timing of hydrocarbon migration or generation. Gas shows in Mbawa-1 well is a result of generated hydrocarbons from the carbonate interbeds in the Upper Cretaceous. Gas shows are pockets trapped in the thin carbonate rich beds. There is low abundance of upper-low, moderate and upper-moderate gravity liquid petroleum inclusions in Kubwa-1 well (central deep offshore). The low abundance suggests migration events rather than paleo-accumulations, possibly involving several discrete charges. Despite sufficient vitrinite reflectance and total organic carbon (TOC) content, the temperatures are still insufficient for hydrocarbon generation in the southern deep offshore in the region where Kiboko-1 well is located. There is no sufficient evidence for access to mature source rocks in the deep offshore basin.