Journal articles: 'Dielectric breakdown in Mott insulators'

1

Eckstein, Martin, and Philipp Werner. "Dielectric breakdown of Mott insulators – doublon production and doublon heating." Journal of Physics: Conference Series 427 (March 27, 2013): 012005. http://dx.doi.org/10.1088/1742-6596/427/1/012005.

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Schilirò, Emanuela, Raffaella Lo Nigro, Fabrizio Roccaforte, and Filippo Giannazzo. "Recent Advances in Seeded and Seed-Layer-Free Atomic Layer Deposition of High-K Dielectrics on Graphene for Electronics." C — Journal of Carbon Research 5, no. 3 (September 2, 2019): 53. http://dx.doi.org/10.3390/c5030053.

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Graphene (Gr) with its distinctive features is the most studied two-dimensional (2D) material for the new generation of high frequency and optoelectronic devices. In this context, the Atomic Layer Deposition (ALD) of ultra-thin high-k insulators on Gr is essential for the implementation of many electronic devices. However, the lack of out-of-plane bonds in the sp2 lattice of Gr typically hinders the direct ALD growth on its surface. To date, several pre-functionalization and/or seed-layer deposition processes have been explored, to promote the ALD nucleation on Gr. The main challenge of these approaches is achieving ultra-thin insulators with nearly ideal dielectric properties (permittivity, breakdown field), while preserving the structural and electronic properties of Gr. This paper will review recent developments of ALD of high k-dielectrics, in particular Al2O3, on Gr with “in-situ” seed-layer approaches. Furthermore, recent reports on seed-layer-free ALD onto epitaxial Gr on SiC and onto Gr grown by chemical vapor deposition (CVD) on metals will be presented, discussing the role played by Gr interaction with the underlying substrates.

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Junge, Paul, Moritz Greinacher, Delf Kober, Patrick Stargardt, and Christian Rupprecht. "Metastable Phase Formation, Microstructure, and Dielectric Properties in Plasma-Sprayed Alumina Ceramic Coatings." Coatings 12, no. 12 (November 29, 2022): 1847. http://dx.doi.org/10.3390/coatings12121847.

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The need for new solutions for electrical insulation is growing due to the increased electrification in numerous industrial sectors, opening the door for innovation. Plasma spraying is a fast and efficient way to deposit various ceramics as electrical insulators, which are used in conditions where polymers are not suitable. Alumina (Al2O3) is among the most employed ceramics in the coating industry since it exhibits good dielectric properties, high hardness, and high melting point, while still being cost-effective. Various parameters (e.g., feedstock type, spray distance, plasma power) significantly influence the resulting coating in terms of microstructure, porosity, and metastable phase formation. Consequently, these parameters need to be investigated to estimate the impact on the dielectric properties of plasma-sprayed alumina coatings. In this work, alumina coatings with different spray distances have been prepared via atmospheric plasma spray (APS) on copper substrates. The microstructure, porosity, and corresponding phase formation have been analyzed with optical microscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Moreover, we present an in-depth analysis of the fundamental dielectric properties e.g., direct current (DC) resistance, breakdown strength, dielectric loss tangent, and permittivity. Our results show that decreasing spray distance reduces the resistivity from 6.31 × 109Ωm (130 mm) to 6.33 × 108Ωm (70 mm), while at the same time enhances the formation of the metastable δ-Al2O3 phase. Furthermore, space charge polarization is determined as the main polarization mechanism at low frequencies.

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Rosch, A. "Breakdown of Luttinger's theorem in two-orbital Mott insulators." European Physical Journal B 59, no. 4 (October 2007): 495–502. http://dx.doi.org/10.1140/epjb/e2007-00312-3.

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Taguchi, Y., T. Matsumoto, and Y. Tokura. "Dielectric breakdown of one-dimensional Mott insulatorsSr2CuO3andSrCuO2." Physical Review B 62, no. 11 (September 15, 2000): 7015–18. http://dx.doi.org/10.1103/physrevb.62.7015.

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Yamakawa, H., T. Miyamoto, T. Morimoto, T. Terashige, H. Yada, N. Kida, M. Suda, et al. "Mott transition by an impulsive dielectric breakdown." Nature Materials 16, no. 11 (August 21, 2017): 1100–1105. http://dx.doi.org/10.1038/nmat4967.

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Kumagai, Shohei, Hiroaki Iguchi, Masahiro Yamashita, and Shinya Takaishi. "Thermally induced electron–hole dissociation dynamics in quasi-one-dimensional bromo-bridged palladium(iii) Mott-insulator [Pd(en)₂Br](Suc-C_n)₂·H₂O (C_n-Y = dialkylsulfosuccinate; n = 5 and 6)." Physical Chemistry Chemical Physics 24, no. 13 (2022): 7978–82. http://dx.doi.org/10.1039/d2cp00051b.

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Thermally induced electron–hole dissociation was suggested by current–voltage characteristics and dielectric properties in bromo-bridged one-dimensional Mott-insulators, [Pd(en)2Br](Suc-Cn)2·H2O (n = 5 and 6).

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Terasaki, I., T. Takayanagi, M. Kogure, and T. Mizuno. "Out-of-plane dielectric response of the two-dimensional Mott insulators." Physica C: Superconductivity 357-360 (September 2001): 96–98. http://dx.doi.org/10.1016/s0921-4534(01)00174-5.

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Abou-Kandil, Ahmed I., Loai Nasrat, and EmanL Fareed. "High temperature vulcanized ethylene propylene diene rubber nanocomposites as high voltage insulators: Dielectric breakdown measurements and evaluation." Polymers and Polymer Composites 30 (January 2022): 096739112211325. http://dx.doi.org/10.1177/09673911221132593.

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The use of porcelain and thermoplastic based materials as High voltage insulators has always been dominant in the industry. Several elastomers were also investigated, mainly Ethylene Propylene Rubber and Silicone rubbers were used as replacement of the traditional Porcelain high Voltage insulators. In this study we experiment with new elastomer, Ethylene propylene diene rubber (EPDM), that is capable of withstanding high voltage as well as being resistant to severe weathering conditions. In addition to having excellent mechanical properties that we discussed elsewhere. Detailed dielectric breakdown measurements were carried out for room temperature vulcanized and high temperature vulcanized samples. The effects of exposure to UV radiation on the dielectric breakdown strength was also studied. Different fillers were used to improve the dielectric breakdown strength of different polymer matrices. Both carbon black based fillers and inorganic fillers were experimented in order to reach optimum mix properties that provide the best dielectric breakdown strength. Resistance to thermal aging and UV radiation was also carried out on EPDM samples.

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Fuertes, V., M. J. Cabrera, J. Seores, D. Muñoz, J. F. Fernández, and E. Enríquez. "Microstructural study of dielectric breakdown in glass-ceramics insulators." Journal of the European Ceramic Society 39, no. 2-3 (February 2019): 376–83. http://dx.doi.org/10.1016/j.jeurceramsoc.2018.08.044.

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11

Kim, Taeyong, Simpy Sanyal, Seongho Jeon, and Junsin Yi. "Prediction of Dielectric Breakdown of OHTL Insulators Using Contact Angle Measurements." ECS Journal of Solid State Science and Technology 10, no. 12 (December 1, 2021): 123010. http://dx.doi.org/10.1149/2162-8777/ac3ff6.

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Porcelain insulators used in overhead transmission lines (OHTL) are exposed to pollution when operational. To observe the effect of external pollution on these insulators, the relationship between the flashover voltage and surface contamination was studied. The flashover voltage drops sharply when contaminants in the wind are deposited on the surface of the insulators in a humid environment. Under wet conditions, the flashover voltage demonstrates a difference of approximately 10 kV depending on the contamination levels. The higher the equivalent salt deposit density, the lower the contact angle. In particular, the flashover voltage under wet conditions decreases exponentially when the contact angle is below 30°. In this case, the condensation area becomes considerably wider, thus exhibiting the difference in the area of the electrolytic conductive film layer forming the leakage path on the surface. Depending on the equivalent salt deposit density and contact angle, the area of condensation is more than doubled. To measure the level of contamination on the surface using this principle, a contact angle measurement method was adopted to predict the dielectric breakdown of the insulator.

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Zulkifeli, M. A., S. N. Sabki, S. Taking, N. A. Azmi, and S. S. Jamuar. "The Effect of Different Dielectric Materials in Designing High-Performance Metal-Insulator-Metal (MIM) Capacitors." International Journal of Electrical and Computer Engineering (IJECE) 7, no. 3 (June 1, 2017): 1554. http://dx.doi.org/10.11591/ijece.v7i3.pp1554-1561.

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A Metal-Insulator-Metal (MIM) capacitor with high capacitance, high breakdown voltage, and low leakage current is aspired so that the device can be applied in many electronic applications. The most significant factors that affect the MIM capacitor’s performance is the design and the dielectric materials used. In this study, MIM capacitors are simulated using different dielectric materials and different number of dielectric layers from two layers up to seven layers. The effect of the different dielectric constants (k) to the performance of the MIM capacitors is also studied, whereas this work investigates the effect of using low-k and high-k dielectric materials. The dielectric materials used in this study with high-k are Al2O3 and HfO2, while the low-k dielectric materials are SiO2 and Si3N4. The results demonstrate that the dielectric materials with high-k produce the highest capacitance. Results also show that metal-Al2O3 interfaces increase the performance of the MIM capacitors. By increasing the number of dielectric layers to seven stacks, the capacitance and breakdown voltage reach its highest value at 0.39 nF and 240 V, respectively.

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Kolodzey, J., E. A. Chowdhury, T. N. Adam, Guohua Qui, I. Rau, J. O. Olowolafe, J. S. Suehle, and Yuan Chen. "Electrical conduction and dielectric breakdown in aluminum oxide insulators on silicon." IEEE Transactions on Electron Devices 47, no. 1 (2000): 121–28. http://dx.doi.org/10.1109/16.817577.

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14

Corraze, B., E. Janod, L. Cario, P. Moreau, L. Lajaunie, P. Stoliar, V. Guiot, et al. "Electric field induced avalanche breakdown and non-volatile resistive switching in the Mott Insulators AM4Q8." European Physical Journal Special Topics 222, no. 5 (July 2013): 1046–56. http://dx.doi.org/10.1140/epjst/e2013-01905-1.

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15

Sohail, Muhammad, Salman Amin, Yasir Butt, and Muhammad Bin Zubaid Ramay. "Aging Performance of Low-Density Polyethylene/Silicone Rubber Blends Insulators Under Contaminated Conditions." Pakistan Journal of Engineering and Technology 5, no. 1 (March 10, 2022): 29–34. http://dx.doi.org/10.51846/vol5iss1pp29-34.

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Insulation materials are a vital part of the electrical system in all kinds of high voltage (HV) Transmission lines. Environmental stresses affect the performance of all types of insulation materials over time. Dielectric breakdown strength (DBS), Hydrophobicity, Leakage current, internal partial discharge and volume resistivity are all three degraded parameters in the service environment. The materials stand best in outdoor insulation, with the lowest partial discharge, highest breakdown strength, high hydrophobic, Lowest Leakage current, and highest volume resistivity. Enhancement of these parameters is a potential avenue for many researchers over the period. In this study, low-density polyethene (LDPE) under different nanofillers, including SiO2, TiO2, TiO2@SiO2, with different weight percentages, are used. This study investigates the behaviour of dielectric breakdown strength (DBS), Hydrophobicity and Leakage Current (LC) for 1000h test under contaminated conditions such as High voltage, heat, ultraviolet (UV) radiations, salt fog, humidity, and acid rain.

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16

Lockwitz, S., and H. Jostlein. "A study of dielectric breakdown along insulators surrounding conductors in liquid argon." Journal of Instrumentation 11, no. 03 (March 22, 2016): P03026. http://dx.doi.org/10.1088/1748-0221/11/03/p03026.

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Tanaka, Yasuhiro, and Kenji Yonemitsu. "Current-voltage characteristics and breakdown mechanism in one-dimensional band and mott insulators attached to electrodes." Journal of the Korean Physical Society 62, no. 12 (June 2013): 2164–67. http://dx.doi.org/10.3938/jkps.62.2164.

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18

UGAJIN, R., S. HIRATA, and Y. MORI. "FERROMAGNETIC AND MOTT TRANSITIONS MODULATED BY VARYING FRACTAL DIMENSIONS IN FRACTAL–SHAPED NANOSTRUCTURES." International Journal of Modern Physics B 15, no. 14 (June 10, 2001): 2025–44. http://dx.doi.org/10.1142/s0217979201006550.

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The ferromagnetic transition in a fractal-shaped structure is analyzed using standard Monte Carlo simulations of discrete spin models. Mott transition of half-filled electrons in a fractal-shaped structure is investigated using Green's functions for a single-band Hubbard model. Our fractal-shaped structure is generated using the dielectric-breakdown model in a three-dimensional lattice, enabling the fractal dimensions to be reduced from three to two. The critical temperature of the ferromagnetic transition and the critical strength of the electron–electron interaction in the Mott transition are dependent on the fractal dimensions, thus the critical values of these phase transitions can be modulated by varying fractal dimensions.

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19

Morita, Kenji, Hiroshi Nozaki, and Kisato Tone. "The Dielectric Breakdown Mechanism of Suspension Insulators due to the Steep Impulse Voltage." IEEJ Transactions on Power and Energy 116, no. 11 (1996): 1415–21. http://dx.doi.org/10.1541/ieejpes1990.116.11_1415.

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20

Neusel, C., H. Jelitto, and G. A. Schneider. "Electrical conduction mechanism in bulk ceramic insulators at high voltages until dielectric breakdown." Journal of Applied Physics 117, no. 15 (April 21, 2015): 154902. http://dx.doi.org/10.1063/1.4917208.

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21

Lefort Borges, Cícero, and Manuel Luís Barreira Martinez. "Using radio frequency and ultrasonic antennas for inspecting pin-type insulators on medium-voltage overhead distribution lines." Ingeniería e Investigación 33, no. 2 (May 1, 2013): 63–69. http://dx.doi.org/10.15446/ing.investig.v33n2.39519.

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This paper summarises the activities undertaken when using antennas (ultrasound and radiofrequency) for identifying insulators in pre-failure state by detecting the noise emitted by the distribution line and correlating this with these insulators (porcelain pin type) dielectric breakdown. This has led to developing low-cost maintenance procedures and providing support and criteria for engineering decisions regarding replacing these insulators. The technique used two detectors; a radio frequency detector was used in a first investigation of a particular distribution line, set to 40 MHz and installed on the roof of a moving vehicle. The ultrasound detector was used for inspecting (phases A, B, C) each structure (pole) selected. Atmospheric conditions had no influence on defining pre-failure insulators (pin type) based on the noise detection technique. Pin type insulators emitting noise should be replaced since measurement was made from the ground and near the base of the post.

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Neff, H., A. N. Lima, E. K. Melcher, C. Moreira, A. S. Barreto Neto, and J. Precker. "An electro-thermal approach to dielectric breakdown in solids: application to crystalline polymer insulators." IEEE Transactions on Dielectrics and Electrical Insulation 17, no. 3 (June 2010): 872–80. http://dx.doi.org/10.1109/tdei.2010.5492261.

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23

SUÑE, JORDI, DAVID JIMENEZ, and ENRIQUE MIRANDA. "BREAKDOWN MODES AND BREAKDOWN STATISTICS OF ULTRATHIN SiO2 GATE OXIDES." International Journal of High Speed Electronics and Systems 11, no. 03 (September 2001): 789–848. http://dx.doi.org/10.1142/s0129156401001003.

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The dielectric breakdown of ultra-thin silicon dioxide films used as gate insulator in MOSFETs is one of the most important reliability issues in CMOS technology. In this paper, two main aspects of oxide breakdown are considered: the modeling of the breakdown statistics and the properties of the two main breakdown modes, namely Soft Breakdown and Hard Breakdown. The most invoked models for the breakdown statistics that relate defect generation and breakdown are reviewed. Particular attention is paid to the percolation models and to a recent cell-based analytic picture. The scaling of the breakdown distribution with oxide thickness is considered and it is shown that both pictures are equivalent for ultra-thin oxides. It is shown that soft and hard breakdown show coincident statistics and this is used to conclude that both breakdown models are triggered by the formation of the same kind of defect-related conduction paths. The big differences in the post-breakdown conduction properties are attributed to phenomena occurring during the very fast breakdown current runaway that determine the area of the final breakdown spot. The properties of soft and hard breakdown are explained within the common framework of a model based on quantum-point-contact conduction. This mesoscopic approach to the post-breakdown conduction is shown to explain the main experimental results including conductance quantization after hard breakdown, the area and thickness independence of the soft-breakdown I(V) characteristics and the statistical correlation between current level and normalized conductance. Finally, we deal with some open questions and relevant issues that are now subject of intensive investigations. The fact that some breakdown events can be tolerated for some digital applications is considered. In this regard, the distinction between breakdown and device failure distributions is made and some implications for device reliability are discussed. It is argued that energy dissipation during the breakdown runaway can determine the breakdown efficiency, the prevalence ratio of soft to hard breakdown, and their variations with stress conditions, experimental setup (series impedance) and sample characteristics.

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Khan, Saadat Ullah, Muhammad Rafiq, and Kashif Imdad. "Temporal Effects of Thermal Stresses on Solid Dielectric Materials under Diverse Voltage Conditions." Pakistan Journal of Engineering and Technology 5, no. 2 (June 15, 2022): 11–16. http://dx.doi.org/10.51846/vol5iss2pp11-15.

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Dielectric materials are an essential part of the power system and their healthy condition is necessary for the stable system operation. Thermal stresses occurring due to faults have adverse effects on the life of insulating materials. To assess the effects of thermal stresses on the life of solid dielectric materials, this work attempts to investigate the effects of thermal stresses on their various parameters such as dielectric strength, thermal conductivity, breakdown time, etc. Effects on these parameters are assessed at different temperatures and time periods using constant and variable alternating current voltage sources. Simulations are performed in COMSOL Multiphysics 5.6. It was found that high temperature due to thermal stresses affects polymer structure, density, length, thermal conductivity, and breakdown strength of insulating materials. Results show that thermal conductivity increases by increasing time and temperature. Results of the study can be valuable for power system operators for the life assessment of field insulators.

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Nesenyuk, T. A. "TESTING OF PROTOTYPE SIGNALING DEVICES FOR INSULATOR CONTROL." World of Transport and Transportation 16, no. 3 (June 28, 2018): 36–49. http://dx.doi.org/10.30932/1992-3252-2018-16-3-4.

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For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version).ABSTRACT The article introduces laboratory studies of RFID tags used for radio frequency identification and control of the dielectric state of linear polymer insulators LK-70, which are used in the overhead power lines, including the contact network. The effect of electrical discharges on RFID technology performance capability, the effect of climatic factors, the angular distance dependence and the speed of registration of RFID tags for signal reception by a terminal for data collection are measured, the breakdown current is determined. The results of tests that confirm the possibility of radio-frequency identification monitoring of the state of insulators are analyzed. Keywords: overhead power line, contact network, polymer insulators, RFID technology, tests, prototypes, built-in signaling device, RFID tags.

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Stark, S. "On the size dependence of the dielectric breakdown strength of solid insulators at room temperature." Journal of the European Ceramic Society 42, no. 2 (February 2022): 462–71. http://dx.doi.org/10.1016/j.jeurceramsoc.2021.10.023.

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Yoneda, Kenji, Yoshihiro Todokoro, and Morio Inoue. "Thin silicon dioxide and nitrided oxide using rapid thermal processing for trench capacitors." Journal of Materials Research 6, no. 11 (November 1991): 2362–70. http://dx.doi.org/10.1557/jmr.1991.2362.

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Electrical characteristics of trench capacitors using RTO (Rapid Thermal Oxidation) oxides, nitroxides, and reoxidized nitroxides as the gate insulators are discussed. High temperature RTO is effective in preventing oxide thinning at the trench corner, and so the dielectric strength of trench capacitors is improved drastically. The mean time to failure (MTTF) of trench capacitors using RTO is more than ten times longer than that of trench capacitors using conventional furnaces. Using reoxidized nitroxides as the gate insulator, superior charge to breakdown (QBD) is obtained. RTP (Rapid Thermal Processing) is superior to the process using the conventional furnace for the gate insulators of trench capacitors. Improvements in temperature uniformity, repeatability, and lessening of slip line formation are essential for RTP equipment to be practical.

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Mitrovic, Ivona Z., Harry Finch, Leanne A. H. Jones, Vinod R. Dhanak, Adrian N. Hannah, Reza Valizadeh, Arne Benjamin B. Renz, Vishal Ajit Shah, Peter Michael Gammon, and P. A. Mawby. "(Invited) Rare Earth Oxides on Wide Band Gap Semiconductors." ECS Meeting Abstracts MA2022-01, no. 19 (July 7, 2022): 1072. http://dx.doi.org/10.1149/ma2022-01191072mtgabs.

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Globally, most recent power electronics converter and device technology has been driven by the unprecedented demand seen within the automotive sector [1]. The latter demands power converters with near 100% energy efficiency, lightweight, compact and reliable. Wide band gap (WBG) semiconductor materials such as GaN and 4H-SiC have emerged as contenders to replace Si in many power electronics applications. Currently, GaN devices based on the high electron mobility transistor (HEMT) architecture are limited commercially to a maximum of 650 V [2,3]. GaN HEMTs have traditionally suffered from a poor thermal conductivity and the “current collapse” phenomenon, limiting their ability to operate within harsh environments. On the other hand, 4H-SiC has a few reliability issues that limit its ubiquitous application in the automotive sector [2]. Currently the GaN based Metal-Insulator-Semiconductor (MIS)-HEMT device is seen to demonstrate superior performance in power electronics applications over the Schottky gate counterpart, due to its inherently lower gate leakage current, together with the ability to provide larger forward gate voltage swing by engineering the threshold voltage between depletion and enhancement mode operation and also an improved gate-drain breakdown voltage. High band gap gate dielectric materials are preferable as they can provide higher tunnelling barriers for electrons and holes, which result in lower gate leakage current. Furthermore, high dielectric constant (high-k) material is also necessary for improved electrostatic control over the channel and improved on-current, which in-turn results in higher transconductance. In terms of SiC based devices, the use of SiO2 proves to be a bottleneck in exploiting full potential of SiC due to the low value of dielectric constant of SiO2 [4]. Since the oxide is subjected to an electric field that is ~2.5x the field in the semiconductor, the breakdown of SiO2 occurs first, and hence causes the breakdown of SiO2/4H-SiC based devices well below the critical electric field of SiC. This shortcoming led to the exploration of high-k dielectrics as gate stacks in 4H-SiC MIS based devices as well as for surface passivation. It is worth noting that SiO2 is the only dielectric commercially used for SiC devices largely due to the unavailability of a reliable high-k dielectric alternative. Most published results focus on use of Al2O3 and HfO2 films [5], however they have yet to become used mainstream in 4H-SiC devices. In this paper, two rare earth high-k oxides, Y2O3 and Sc2O3, both with dielectric constant >10, have been studied in terms of their suitability as gate dielectrics on GaN and 4H-SiC. The oxide films were prepared by radio frequency (RF) magnetron sputtering (Sc2O3) and ion gun sputtering (Y2O3). The substrates were cleaned with Kr ions with anode current of ~ 50 mA and accelerating voltage of 3 kV for 1-2 hours. Then metallic Y was sputtered using pressure of 1.5 x 10-5 mbar and current of 26 mA, which was followed by exposure to O2 to form Y2O3 films. Sc2O3 films were deposited using Moorfields nano-PVD (physical vapour deposition) equipment with circular Sc2O3 target of 99.99% purity using RF power of 60 W and a gas flow of 0.5 sccm for 3 nm film and 3 sccm for 40 nm film. The films were also deposited simultaneously on Si to be used as reference samples for variable angle spectroscopic ellipsometry (VASE) measurements to ascertain their thickness and optical properties. The X-ray photoelectron spectroscopy (XPS) was used to characterise comprehensively the oxide/semiconductor interface. The capacitance voltage measurements on MIS stacks were used to determine permittivity of deposited oxides. The complete band alignment of oxide/WBG semiconductor as well as comprehensive comparison to state of the art data will be presented and discussed in full paper. Acknowledgement. The UKIERI IND/CONT/G/17-18/18 and F.No.184-1/2018(IC) project funded by the British Council; UKRI GCRF GIAA award 2018/19 and EP/P510981/1, funded by the EPSRC, UK. References. [1] http://www.yole.fr/Compound_Semiconductor_Monitor_Q1.aspx. [2] Li et al., Materials 14, 5831 (2021); [3] Gonzalez et al. IEEE Trans. Ind. Electron. 67, 7375 (2020); [4] A. Siddiqui et al., J. Mater. Chem. C 9, 5055 (2021); [5] Bencherif et al., Appl. Phys. A 126, 854 (2020).

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Cajetan, Okolo Chidiebere, Ezechukwu O.A., Olisakwe C.O., Ezendokwelu C.E., and Umunna Chike. "CHARACTERIZATION OF ELECTRICAL PORCELAIN INSULATORS FROM LOCAL CLAYS." International Journal of Research -GRANTHAALAYAH 3, no. 1 (January 31, 2015): 26–36. http://dx.doi.org/10.29121/granthaalayah.v3.i1.2015.3050.

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In this thesis, the characterization of electrical porcelain insulators based on local clays has been investigated. Test samples were made by varying the quantities of feldspar and silica required to form a mouldable plastic body with each clay sample. The clay samples were bisque fired which is to 900°C and glazed before it was fired to 1250°C after air-drying. An electrical property such as dielectric strength (breakdown voltage) was determined for each test sample that survived the high temperature. The composition for optimum properties from Ekwulobia and Iva Valley clays each is at composition 3 of 60% clay, 25% feldspar and 15% silica; while for Nawfija clay, the composition for optimum properties was 50% clay, 30% feldspar and 20% silica. Porcelain insulators containing 50-70% clay, 20-30% feldspar and 10-20% silica were found to have requisite properties that make them suitable for domestic production of porcelains insulators from the clay samples studied.

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30

Mitra, Kalyan Yoti, Enrico Sowade, Christoph Sternkiker, Carme Martínez-Domingo, Eloi Ramon, Jordi Carrabina, and Reinhard R. Baumann. "Investigation on Electrical Stress over Metal-Insulator-Metal (MIM) Structures Based on Compound Dielectrics for the Inkjet-Printed OTFT Stability." Applied Mechanics and Materials 748 (April 2015): 129–33. http://dx.doi.org/10.4028/www.scientific.net/amm.748.129.

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One of the greatest challenges in the field of printed electronics is the performance stability of the devices fabricated by the different printing technologies e.g. inkjet or gravure printing technology. The performance instability can be defined in terms of the device breakdown or by other effects like the emergence of leakage current under the constant high voltage inputs (especially the dielectric within the transistor architecture). The reasons behind this phenomenon can be various, but the most prominent indication can be detected from the materials used and the deposition methodology. For this purpose the herein work is presented, targeting on the all inkjet-printed organic thin film transistor (OTFT), but keeping the focus on the basic building block for fabricating inkjet-printed OTFTs. In this case it is the metal-insulator-metal (MIM) layer structure. Herein, the MIM structures are inkjet-printed, and then characterized optically and electrically. The dielectric layers for the MIM structures are printed using three different dielectric ink materials either individually 1) Single component system; or in combination with each other as in form of bi-layer stack 2) Multiple component system. The thickness of the printed dielectric layers is varied for these MIM structures. The electrical characterization is performed with respect to current vs. applied voltage and is done for a large number of iterations. The leakage current is of interest and shows a negative and positive trend towards the single component system and multiple component system for the dielectric layers in the MIM characterization structures respectively.

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Lima, A. M. N., A. G. S. Barreto Neto, E. U. K. Melcher, and H. Neff. "Refined dielectric breakdown model for crystalline organic insulators: electro-thermal instability coupled to interband impact ionization." IEEE Transactions on Dielectrics and Electrical Insulation 18, no. 4 (August 2011): 1038–45. http://dx.doi.org/10.1109/tdei.2011.5976093.

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32

Zhang, Jianwei, Hongguang Wang, Yongdong Li, Chunliang Liu, Wei Luo, and Jiawei Zhang. "Evolution of vacuum surface flashover for angled dielectric insulators with particle-in-cell simulation." Physics of Plasmas 29, no. 4 (April 2022): 043506. http://dx.doi.org/10.1063/5.0082530.

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With the introduction of the gas diffusion model, the surface flashover at the insulator–vacuum interface perpendicular to electrodes is simulated with the particle-in-cell method. The distributions of density of electrons, ions, and neutral gas molecules are obtained, which is consistent with images diagnosed in the experiment. The gas pressure at the dielectric surface near electrodes is much higher than it is at other locations. Furthermore, the processes of vacuum surface flashover for angled dielectric insulators are analyzed. The results show that negative charges will accumulate on the dielectric surface when the negative angle is large. The electric field produced by negative charges weakens the normal electric field and emission current on the cathode triple junction. Moreover, the process of secondary electron emission is completely suppressed when the negative angle is large. With the development of gas desorption, the breakdown will evolve from field emission into gas ionization. Therefore, when the angle is negative, the threshold of surface flashover first decreases then increases with the angle, which is in good agreement with laws obtained in experiments. This study can provide a deep understanding to the vacuum surface flashover.

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Kovalchuk, N. S., A. A. Omelchenko, V. A. Pilipenko, V. A. Solodukha, S. V. Demidovich, V. V. Kolos, V. A. Filipenia, and D. V. Shestovski. "Research of Electrophysical Properties of Thin Gate Dielectrics Obtained by Rapid Thermal Processing Method." Doklady BGUIR 20, no. 4 (June 29, 2022): 44–52. http://dx.doi.org/10.35596/1729-7648-2022-20-4-44-52.

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Researches of the electrophysical characteristics of gate dielectrics obtained by the rapid thermal processing (RTP) method by two-stage and three-stage processes have been carried out. Each photonic processing (stage) was carried out for 12 s at a constant power of halogen lamps and heating the wafers to a maximum temperature of 1250 °C. The first two stages of the process were carried out in an oxygen atmosphere, the third - in nitrogen or a forming gas. It was found that for dielectrics obtained by the process with final processing in a nitrogen atmosphere, the absolute value of the voltage of flat zones is 0.42 V less, than for insulators, formed by a two-stage process. This is the consequence of the elimination of a significant part of the defects, responsible for the presence of Coulomb centers in the dielectric layer. Carrying out photonic processing in anitrogen atmosphere at high temperatures of procedures for proceeding of the restructuring of the structure of the dielectric layer. For insulators obtained by a three-stage process with final processing in N2, an increase in dielectric strength and breakdown voltage by 1 V and 3.3 MV/cm, respectively, is observed in comparison with dielectrics, obtained by a two-stage process. An increase in dielectric strength indicates relaxation of elastic stresses of deformed bonds and compensation for dangling bonds both in the dielectric and at its interface with Si during high-temperature photonic treatment. Passivation by nitrogen atoms of deformations at the dielectric/semiconductor interface will also have a positive effect on the strength of the insulator.

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Muangpratoom, Pichai, Issaraporn Khonchaiyaphum, and Wanwilai Vittayakorn. "Improvement of the Electrical Performance of Outdoor Porcelain Insulators by Utilization of a Novel Nano-TiO2 Coating for Application in Railway Electrification Systems." Energies 16, no. 1 (January 3, 2023): 561. http://dx.doi.org/10.3390/en16010561.

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The present study aimed to develop the electrical performance of outdoor insulators using a nano-TiO2 coating for railway electrification systems. The prototype design of porcelain insulators with normal coatings and using a nano-TiO2 coating is based on IEC 60815-1. The first test was performed to measure the low-frequency flashover AC voltage under both dry and wet conditions. In addition, the other test was conducted to measure the lightning impulse critical-flashover voltage at positive and negative polarity under dry-normal and wet-contaminated conditions. X-ray diffraction (X-RD) and Scanning electron microscopy (SEM) were used to examine the micro surface and show that the nano-TiO2 coating was adhered to the surface of the outdoor porcelain insulator and exists in an amorphous state. Additionally, it was observed and discovered that scattered nano-TiO2 strengthens the glassy matrix and creates a sturdy barrier that causes flashover voltage to be reduced under conditions of high dielectric strength. Nanostructured ceramic formulations outperform ordinary porcelain in terms of breakdown voltage strength, particularly for the insulators’ low-frequency flashover performances under dry and wet test conditions. However, a significant change in the lightning impulse critical-flashover voltage characteristics is observed and is not much better when adding the nano-TiO2 coating to the porcelain insulators.

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Wajanasoonthon, Kanin, and Amnart Suksri. "Long Term Thermal Performance of Palm Oil and Nano Graphene Filler in Nanofluids Application on Transformer Insulating Oil and Electrical Breakdown Voltage." Key Engineering Materials 931 (September 9, 2022): 9–15. http://dx.doi.org/10.4028/p-bhz05b.

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Mineral oil has been used as electrical insulation for a long time due to its availability, excellent cooling and dielectric property. However, petroleum sources are nonrenewable, and it is depleting. Vegetable insulating oil is an alternative since it is renewable, environment-friendly, biodegradable, high fire-point, and has a good electrical breakdown voltage level. These properties can make vegetable insulating oil as a replacement for mineral oil that is going to be limited in availability. Nevertheless, vegetable insulating oil have high viscosity, leading to a slow flow rate on the cooling performance. This research is to investigate the breakdown voltage of palm oil-based liquid insulators. This liquid is palm oil methyl esters-based nanofluids (NPME) that was converted from the transesterification process to reduce viscosity and mixed with graphene nanoparticles. These nanofluids were also aged by thermal aging at 100 °C for 168, 336 and 504 hours before testing for their electrical breakdown voltage. The results show that the transesterification process can reduce the viscosity of palm oil by about 6.6 times. Also, the breakdown voltage of nanofluids is higher than bare palm oil methyl ester after thermal aging for 504 hours.

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Golovko, Sergey Vladimirovich, and Julia Aleksandrovna Golovko. "Software and hardware complex based on technical vision for diagnosing electrical insulators." Vestnik of Astrakhan State Technical University. Series: Management, computer science and informatics 2022, no. 3 (July 29, 2022): 30–37. http://dx.doi.org/10.24143/2072-9502-2022-3-30-37.

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Control of the equipment dielectric insulation is one of the most important types of diagnostics in operation of the electrical networks, because the defects cause ionization of voids and partial corona discharges. These discharges gradually destroy the insulation causing the energy loss, radio interference and decreasing the fire safety of the operated electrical equipment. Common failures of electrical insulators are breakdowns, overlaps and mechanical damage. The need to determine the resistance against the surface discharges increases in case of using the new polymer materials due to their characteristics. Developing the systems with computer (technical) vision is one of the ways for implementing automated control of the quantity and the area of corona discharges. The long-term experience of diagnostics accumulated by the specialists by using the ultraviolet flaw detectors and thermovision cameras has demonstrated the high efficiency in checking the damages in the high-voltage equipment and power lines. Application of vision technologies in the hardware and software complex will eliminate errors in checking and analyzing the flares, as well as minimize human participation in a number of monotonous operations, reduce the loss of working time caused by the human factor, protect the life and health of workers.

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Se-Ondoua, MuD Malec, N. Zebouchi, and Hoang-The-Giam. "Study of space charge effect on dielectric DC breakdown of synthetic insulators with the pressure wave propagation method." Journal of Electrostatics 40-41 (June 1997): 355–61. http://dx.doi.org/10.1016/s0304-3886(97)00070-3.

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Zheng, Jianjun, Shaojian He, Jiaqi Wang, Wenxuan Fang, Yang Xue, Liming Xie, and Jun Lin. "Performance of Silicone Rubber Composites Filled with Aluminum Nitride and Alumina Tri-Hydrate." Materials 13, no. 11 (May 29, 2020): 2489. http://dx.doi.org/10.3390/ma13112489.

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In this study, silicone rubber (SR) composites were prepared with various amounts of aluminum nitride (AlN) and alumina tri-hydrate (ATH), and vinyl tri-methoxysilane (VTMS) was also introduced to prepare SR/ATH/AlN–VTMS composites for comparison. Compared to the SR/ATH composites, the SR/ATH/AlN composites with higher AlN loading exhibited higher breakdown strength and thermal conductivity, which were further improved by the addition of VTMS. Such results were related to the enhanced rubber–filler interfacial interactions from VTMS coupling, as demonstrated by scanning electron microscopy (SEM) analysis and the curing behaviors of the SR composites. Moreover, by replacing ATH with VTMS-coupled AlN, the SR/ATH/AlN–VTMS composites also exhibited lower dielectric loss along with an increased dielectric constant, suggesting the promising application of VTMS-coupled AlN as a filler for the preparation of the SR composites as high-voltage insulators.

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Eckstein, J. N., I. Bozovic, and G. F. Virshup. "Atomic Layer-by-Layer Engineering of High Tc Materials and Heterostructure Devices." MRS Bulletin 19, no. 9 (September 1994): 44–50. http://dx.doi.org/10.1557/s0883769400047989.

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Oxides exhibit most of the interesting phenomena known to occur in solid-state systems. As a class of materials they may be richer in phenomenology than any other comparable class. Oxides can be insulators, semiconductors, or metals. The copperoxide-based compounds we have studied are superconductors with the highest critical temperatures. In some oxides, electrons manifest simple single-particle transport properties, with a high mobility; in others, they show strongly correlated behavior resulting in a Mott-Hubbard transition, localization, and charge- or spin-density waves. In some oxides, electron-phonon coupling leads to polaronic transport. Others show collective states such as magnetism; in some there are large local magnetic moments that can couple to form ferromagnetic or antiferromagnetic phases that exist up to high temperatures. Yet others have large nonlinear dielectric and optical properties. In fact, it would seem there is very little that some such oxide couldn't do for or to the experimenter.

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Mukherjee, Kalparupa, Carlo De Santi, Matteo Borga, Shuzhen You, Karen Geens, Benoit Bakeroot, Stefaan Decoutere, Gaudenzio Meneghesso, Enrico Zanoni, and Matteo Meneghini. "Use of Bilayer Gate Insulator in GaN-on-Si Vertical Trench MOSFETs: Impact on Performance and Reliability." Materials 13, no. 21 (October 23, 2020): 4740. http://dx.doi.org/10.3390/ma13214740.

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We propose to use a bilayer insulator (2.5 nm Al2O3 + 35 nm SiO2) as an alternative to a conventional uni-layer Al2O3 (35 nm), for improving the performance and the reliability of GaN-on-Si semi vertical trench MOSFETs. This analysis has been performed on a test vehicle structure for module development, which has a limited OFF-state performance. We demonstrate that devices with the bilayer dielectric present superior reliability characteristics than those with the uni-layer, including: (i) gate leakage two-orders of magnitude lower; (ii) 11 V higher off-state drain breakdown voltage; and (iii) 18 V higher gate-source breakdown voltage. From Weibull slope extractions, the uni-layer shows an extrinsic failure, while the bilayer presents a wear-out mechanism. Extended reliability tests investigate the degradation process, and hot-spots are identified through electroluminescence microscopy. TCAD simulations, in good agreement with measurements, reflect electric field distribution near breakdown for gate and drain stresses, demonstrating a higher electric field during positive gate stress. Furthermore, DC capability of the bilayer and unilayer insulators are found to be comparable for same bias points. Finally, comparison of trapping processes through double pulsed and Vth transient methods confirms that the Vth shifts are similar, despite the additional interface present in the bilayer devices.

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Liu, Chang, Yiwen Xu, Daoguang Bi, Bing Luo, Fuzeng Zhang, Tingting Wang, Yingbang Yao, Shengguo Lu, and Wenrong Xu. "The Effects of Aluminum-Nitride Nano-Fillers on the Mechanical, Electrical, and Thermal Properties of High Temperature Vulcanized Silicon Rubber for High-Voltage Outdoor Insulator Applications." Materials 12, no. 21 (October 30, 2019): 3562. http://dx.doi.org/10.3390/ma12213562.

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AlN nanoparticles were added into commercial high-temperature-vulcanized silicon rubber composites, which were designed for high-voltage outdoor insulator applications. The composites were systematically studied with respect to their mechanical, electrical, and thermal properties. The thermal conductivity was found to increase greatly (>100%) even at low fractions of the AlN fillers. The electrical breakdown strength of the composites was not considerably affected by the AlN filler, while the dielectric constants and dielectric loss were found to be increased with AlN filler ratios. At higher doping levels above 5 wt% (~2.5 vol%), electrical tracking performance was improved. The AlN filler increased the tensile strength as well as the hardness of the composites, and decreased their flexibility. The hydrophobic properties of the composites were also studied through the measurements of temperature-dependent contact angle. It was shown that at a doping level of 1 wt%, a maximum contact angle was observed around 108°. Theoretical models were used to explain and understand the measurement results. Our results show that the AlN nanofillers are helpful in improving the overall performances of silicon rubber composite insulators.

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Lucchini, Francesco, Nicolò Marconato, and Paolo Bettini. "Automatic Optimization of Gas Insulated Components Based on the Streamer Inception Criterion." Electronics 10, no. 18 (September 17, 2021): 2280. http://dx.doi.org/10.3390/electronics10182280.

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Gas insulated transmission lines (GILs) are used in electrical systems mainly for power transmission and High Voltage substation interconnection. In this paper, we focus on the development of complex numerical tools for the optimization of gas insulated HVDC components by the estimation of realistic electric field distribution and the voltage holding of the designed geometry. In particular, the paper aims at describing the correct modelling approach suitable to study high voltage components in DC, considering the nonlinear behaviour characterizing the electrical conductivity of solid and gas insulators. The simulated field distribution is then adopted to estimate the voltage holding of the dielectric gas, with a convenient engineering technique, based on the streamer criterion. These two tools are integrated in an automatic optimization package developed in COMSOL® and MATLAB®, with the purpose of adjusting the critical geometry features, suffering from excessive electrical stress and possibly giving rise to electrical breakdown, in order to guide the designer towards a robust solution.

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Kannan, V. C. "Fresnel fringe contrast in the TEM: Application to study the microstructure of amorphous silicon." Proceedings, annual meeting, Electron Microscopy Society of America 49 (August 1991): 1000–1001. http://dx.doi.org/10.1017/s0424820100089317.

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Amorphous silicon-hydrogen (α - Si:H) alloy films deposited by plasma enhanced chemical vapor deposition (PECVD) of silane exhibit a remarkable property; namely, the films are practically insulators in the as deposited state. When sandwiched between two metals or highly conductive refractory metal silicides, the films can be converted to near conductivity state by “programming” the sandwich structure to complete dielectric breakdown of the insulator. Such α - Si:H films are used in permanently programmable integrated circuits such as PGA (Programmable Gate Arrays) as “antifuse” materials.TEM technique has, usually, limited application to study the microstructure of amorphous materials since they do not exhibit the well understood diffraction contrast as seen in crystalline materials. However, Fresnel fringe contrast due to electron interference effects at either sides of interfaces or at the edges can be used to provide the sort of information needed to characterize amorphous films. The profiles of Fresnel fringes are often complex for interface thickness of <100 A and their shape and contrast are very sensitive to compositional changes on either sides of the interfaces.

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Xayyavong, Mingkhouan, Kittipong Tonmitr, Norrawit Tonmitr, and Eiji Kaneko. "The Scrutiny of the Insulation Breakdown Strength for the Nanocomposite Oxide Doped Epoxy Resin Insulator with Different Electrodes by Using Positive Impulse Voltage." Key Engineering Materials 705 (August 2016): 63–67. http://dx.doi.org/10.4028/www.scientific.net/kem.705.63.

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This research presents the ratio of doping nanocomposite oxides in dielectric materials for increasing the efficiency strength and endurance voltage. Tests were conducted and analyzed the characteristics of epoxy nanozinc oxides. By using positive standard impulse voltage abilities of nanocomposite oxides were used as electrical insulators-epoxy resin doped with zinc oxides nanocomposite in ratios of 0, 5, 10, 15, and 20% by weight. And the design of electrodes embeds in the specimens with 4 types of electrode, as needle electrode, point electrode, spherical electrode and the partial spherical electrode. When adjusted the impulse voltage level of 75kV to the specimen immersed in transformer oil. The experiment aforementioned to investigate the ratios damages on insulator surfaces and the number of breakdowns. The microscopes with magnification levels of 20-800X were used to view the damages on insulator surfaces. Results, it was found that regarding specimens used for doping an epoxy resin with zinc oxides nanocomposite in a ratio of 5% had high withstand insulator with electrode types. The partial spherical electrode tested with positive impulse standard voltage has destructive distance lower damage than other electrode types.

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Liu, Yunpeng, Wanxian Wang, Hechen Liu, Mingjia Zhang, Jie Liu, and Junwei Qi. "Blending Modification of Alicyclic Resin and Bisphenol A Epoxy Resin to Enhance Salt Aging Resistance for Composite Core Rods." Polymers 14, no. 12 (June 13, 2022): 2394. http://dx.doi.org/10.3390/polym14122394.

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In order to promote the application of composite insulators in coastal areas with high temperature, high humidity and high salt, it is of great importance to develop matrix resin with salt corrosion resistance for composite core rods. In this study, bisphenol A epoxy resin was modified by blending with alicyclic epoxy resin (2021P). Three different proportions of 2021P/DGEBA blend resins (0% 2021P/DGEBA, 10% 2021P/DGEBA and 20% 2021P/DGEBA) were prepared, and the high salt medium corrosion test was carried out. The physicochemical (FTIR, DMA, TGA) and electrical properties (dielectric loss, leakage current and breakdown field strength) of the blend resin before and after aging were tested and analyzed, and the optimal blend proportion was determined. The results showed that after salt aging, the Tg of 0% 2021P/DGEBA decreased to 122.99 °C, while the Tg of 10% 2021P/DGEBA reached 134.89 °C; The leakage current of 0% 2021P/DGEBA increased to 48.994 μA, while that of 10% 2021P/DGEBA only increased to 44.549 μA; The breakdown field strength of 0% 2021P/DGEBA dropped to 40.36 kv/mm, while that of 10% 2021P/DGEBA only dropped to 43.63 kv/mm. The introduction of 2021P enhanced the salt corrosion resistance of the blend resin, which could hinder the penetration, diffusion and erosion of external media (such as Na+, Cl−, H2O, etc.) to the matrix resin. The comprehensive properties of 10% 2021P/DGEBA blend system reached the best, which was better than other blending resins, showing great application potential.

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Pinterić, M., T. Ivek, M. Čulo, O. Milat, M. Basletić, B. Korin-Hamzić, E. Tafra, A. Hamzić, M. Dressel, and S. Tomić. "What is the origin of anomalous dielectric response in 2D organic dimer Mott insulators κ-(BEDT-TTF)2Cu[N(CN)2]Cl and κ-(BEDT-TTF)2Cu2(CN)3." Physica B: Condensed Matter 460 (March 2015): 202–7. http://dx.doi.org/10.1016/j.physb.2014.11.071.

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Renz, Arne Benjamin Benjamin, Oliver J. Vavasour, Peter Michael Gammon, Fan Li, Tianxiang Dai, Guy W. C. Baker, Nicholas E. Grant, et al. "(Invited, Digital Presentation) Improved Reliability of 4H-SiC Metal-Oxide-Semiconductor Devices Utilising Atomic Layer Deposited Layers with Enhanced Interface Quality." ECS Meeting Abstracts MA2022-01, no. 19 (July 7, 2022): 1065. http://dx.doi.org/10.1149/ma2022-01191065mtgabs.

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A major component of reliability of Silicon Carbide (4H-SiC) power electronics are due to the gate dielectric. Specific aspects such as hysteresis, insulator lifetime, threshold voltage (VTH) instability and high leakage currents, remain an issue of paramount importance which hamper the uptake of 4H-SiC power MOSFETs.1 The oxide understood to have the most importance is coincidently the native oxide, SiO2, due to the suitable band offset to 4H-SiC. However, most of the SiO2/SiC interface problems, such as carbon clusters, H content and O vacancies, are directly related to the thermal oxidation process.2 Here, we show these issues can partially be avoided by using dielectric deposition instead. Atomic layer deposition (ALD) offers specific advantages such as very low deposition temperature, excellent process control and suitability for conformal deposition of gate oxides in trench structures.3 Deposited oxides still require a post-deposition anneal (PDA) in a nitrogen-containing ambient4 such as nitrous oxide (N2O) or nitric oxide (NO) [2] to passivate the defects within the stack and improve the as-deposited layer’s poor electrical quality. We present the excellent reliability performance of ALD-deposited SiO2 layers on SiC through fabrication of metal-oxide-semiconductor capacitors (MOSCAPs) and then using time-dependent dielectric breakdown (TDDB) characterisation. The distribution of interface parameters, as well as the results from TDDB, have been investigated as metrics of improvement following the N2O PDA process. For benchmarking, processes will be compared to thermally grown oxides4 and LPCVD-deposited dielectric layers to demonstrate the superior process quality. An active 10 µm thick epitaxial layer of 4 × 1015 cm-3 n-type doping is used in this study and grown on 100 mm diameter, 4° off-axis (0001) 4H-SiC wafers. Growth was performed using a 30 μm/hr growth and N2 as a dopant in an LPE ACiS M8 chemical vapour deposition (CVD) reactor. After an initial clean, a 1 µm thick field oxide was deposited and a window was opened via photolithography and reactive ion etching (RIE). Then, quarter wafers underwent one of the three oxidation routines: 1. SiO2 plasma deposition at 200 °C using bis(diethylamino)silane (BDEAS) and O2 plasma precursors in an Ultratech Fiji G2 Plasma-Enhanced ALD System. 2. SiO2 deposition at 750 °C using tetraethyl orthosilicate (TEOS) as a precursor in a Thermco LPCVD system. 3. direct thermal growth of SiO2 in a HiTech furnace at 1300 °C for 5 hrs in N2O ambient. Samples that had undergone one of the first two routines then underwent a PDA in N2O, in the HiTech furnace at 1300°C for 2 hrs. All oxidation measurements resulted in oxide thicknesses between 50 and 60 nm, which were verified using step-height AFM measurements and optical interferometry. To create the vertical MOSCAP structure samples had a 500 nm aluminium (Al) backside contact deposited, before a 1 μm Al layer was deposited on the topside of the samples by means of a liftoff process. A cross-sectional diagram of the fabricated final device structure is shown in Fig. 1 (a). Table I shows the key electrical parameters which were extracted using room temperature C-V measurements, combined with I-V and constant field TDDB measurements at 175 °C. Fig. 1 (b) shows the improvement brought about by the N2O anneal, which also results in the average flatband voltage being reduced by more than 10 V to the lowest value of the dataset (1.44 V) and frequency dispersion mostly removed, with all but the ALD as-deposited samples reaching average breakdown oxide fields of about 10 MV/cm. The most promising improvement of the ALD-deposited SiO2 can be seen observing the breakdown distribution of MOSCAPs when stressed at constant high electric field (9 MV/cm), which can be seen in Fig. 2 (a) and (b). Here, these samples reach a TDDB, 63% value of 4786 s, which represents an average increase of 28% when compared to LPCVD samples and 58% when comparing this to a purely thermal process. Further evidence will be presented that high-quality, high-reliability SiO2 layers, formed by ALD and PDA have been formed. Flatband voltage and hysteresis are reduced, compared to thermally grown oxide, and frequency dispersion in accumulation is negligible. The ALD oxide with PDA has higher reliability than LPCVD and thermal oxides in TDDB tests, offering 29% to 345% improvement. The degradation mechanisms of the ALD oxide are different to that the LPCVD and thermal oxides and will be discussed in this talk. [1] P. Moens et al, ISPSD 32, 78-71 (2020). [2] P. Fiorenza et al, Appl. Surf. Sci., 149752 (2021). [3] A. Renz et al, MSSP 122, 105527 (2021). [4] K. Tachiki et al, Appl. Phy. Expr. 13.12, 121002(2020). Figure 1

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Rashid, Arooj, Jawad Saleem, Muhammad Amin, and Sahibzada Muhammad Ali. "Long-term aging characteristics of co-filled nano-silica and micro-ATH in HTV silicone rubber composite insulators." Polymers and Polymer Composites 29, no. 1 (January 26, 2020): 40–56. http://dx.doi.org/10.1177/0967391120901421.

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Multiple environmental stresses produce complex phenomena of aging in polymeric insulators. The main aim of this research is to investigate the improved aging characteristics of silica (SiO2)/alumina trihydrate (ATH) hybrid samples (HSs) in high-temperature vulcanized rubber. For this purpose, three HSs comprising 20% micro-ATH with 2% nano-SiO2 (S2), 4% nano-SiO2 (S4), 6% nano-SiO2 (S6) along with sample-virgin (SV) are subjected to long-term accelerated aging of 9000 h. A special aging chamber is fabricated for the aging process of samples. The aging characteristics of these samples are investigated by measuring leakage current (LC) and hydrophobicity classification (HC) after every weathering cycle. Similarly, Fourier transform infrared (FTIR) spectroscopy is performed to observe the important structural changes over the entire aging time. The dielectric strength of AC is also performed after every 1000 h of aging. Tracking and erosion resistance and mechanical properties are also investigated before and after aging. From the critical investigation, it is observed that HSs possess improved results in all the conducted tests. S2 has the lowest LC and HC values throughout the aging time. Similarly, S6 described the highest breakdown strength at the end of the accelerated aging. In the case of FTIR, it is analyzed that the important wave numbers remain intact for all the HSs in the accelerated aging environment. The loss percentage in the wave number for SV is higher, compared to the HSs. After performing the tracking and erosion resistance test, HSs have superior performance. For some of the mechanical properties, HSs showed improved values. Thus, from the experimental analysis, it is deducted that the sample S2 offers the highest resistance to the aging conditions, compared to the SV and other HSs.

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Raicevic, Nebojsa B., and Nikola Raicevic. "Reducing the impact of ELF electromagnetic fields of HV power cables on the environment by modeling the cable accessories." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 34, no. 4 (July 6, 2015): 1016–28. http://dx.doi.org/10.1108/compel-10-2014-0251.

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Purpose – Underground cables can produce higher electromagnetic fields directly above them than an overhead line. The majority of cable failures on distribution system are caused by defects in the cable accessories. Nowadays, significant research has been carried out worldwide into examining whether electricity, and in particular, the presence of electric and magnetic fields have an adverse impact on health, especially the occurrence of cancer and childhood leukemia. The purpose of this paper is to optimize the electric field distribution in underground cable accessories. This reduces the impact of the harmful effects of the fields on living beings and humans. Design/methodology/approach – Cable terminations and joints are designed to eliminate the stress concentration at the termination screen to avoid the breakdown of the cable and high values of electric field at these points. Any improvement in the cable termination and joints construction is of great interest. There are several methods for the solution of electric field distribution. These can be summarized as analytical, experimental, free-hand field mapping, analogue methods and numerical methods. In this paper cable accessories are modeled by using multilayer dielectric system and very thin deflector’s cones. Findings – This model includes specific insulators design and smart choice of electrodes position. Stress-grading nonlinear materials in form of tapes and tubes were used with much success. In order to optimize the cable joint parameters, two criteria were monitored – total electric field magnitude and magnitude of the tangential component. More than 30 percent is reduced impact of cables on the environment. Originality/value – In order to investigate the accuracy of the applied numerical model, various configurations of the cable accessories are studied. The first time is applied new Hybrid Boundary Elements Method on the protection of the environment.

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Schadler, Linda S., Wei Chen, L. Catherine Brinson, Ravishankar Sundararaman, Prajakta Prabhune, and Akshay Iyer. "(Invited) Combining Machine Learning, DFT, EFM, and Modeling to Design Nanodielectric Behavior." ECS Meeting Abstracts MA2022-01, no. 19 (July 7, 2022): 1068. http://dx.doi.org/10.1149/ma2022-01191068mtgabs.

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Polymer Nanodielectrics are class of materials with intriguing combinations of properties. Predicting and designing the properties, however, is complex due to the number of parameters controlling the properties. This makes it difficult to compare results across groups, validate models, and develop a design methodology. This presentation will share a recent approach to developing a data driven design methodology grounded in physics-based models and experimental calibration. We combine finite element modeling of dielectric constant and loss functions with a Monte Carlo multi-scale simulation of carrier hopping to predict break down strength. Filler dispersion, filler geometry, isotropy and interface properties are explicitly taken into to account to compute objective functions for ideal nanodielectric insulators. Further, we have used machine learning to develop an EFM technique for directly measuring the dielectric constant of the nanoscale interfacial region as critical input to our models. Ultimately, we calculate the Pareto frontier with respect to nanocomposite constitute properties and geometry to optimize properties. The finite element approach can be used to forward predict properties based on the properties of the interfacial region and filler dispersion, or as an inverse tool to calculate interface properties or develop optimized filler morphologies. The breakdown strength model critically depends on the energy distribution of trap states that inhibit space charge motion. We have developed an ab initio approach to determine the trap states at amorphous interfaces, and have used that to do a systematic analyses of trap distributions in composites with functionalized particle interfaces. The models all use 3D particle distributions based on 2D imaging (TEM) of the composites and publicly available tools for binarization and characterization of filler morphology. Finally, we use a design of experiment approach (Latin Hybercube Design) to sample the complete experimental design space, and using calibrated models and morphologies, create a data set spanning the full set of parameters. We use the data from the DOE to train a Gaussian Process metamodel and a genetic algorithm to determine which designs fulfill the design parameters. The talk will present several case studies as examples. The data for this work was accessed from a new data resource, MaterialsMine, using FAIR (Findable, Accessible, Interoperable, and Reusable) principles. MaterialsMine is an open source data repository, and resource. It includes unique visualization tools as well as modeling and characterization resources.

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Journal articles on the topic 'Dielectric breakdown in Mott insulators'

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