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Showing papers on "Insulator (electricity) published in 2012"


Journal ArticleDOI
TL;DR: In this paper, the electronic structure of silicene and the stability of its weakly buckled honeycomb lattice in an external electric field oriented perpendicular to the monolayer of Si atoms were analyzed.
Abstract: We report calculations of the electronic structure of silicene and the stability of its weakly buckled honeycomb lattice in an external electric field oriented perpendicular to the monolayer of Si atoms. The electric field produces a tunable band gap in the Dirac-type electronic spectrum, the gap being suppressed by a factor of about eight by the high polarizability of the system. At low electric fields, the interplay between this tunable band gap, which is specific to electrons on a honeycomb lattice, and the Kane-Mele spin-orbit coupling induces a transition from a topological to a band insulator, whereas at much higher electric fields silicene becomes a semimetal.

969 citations


Journal ArticleDOI
TL;DR: In this article, the band structure of a two-dimensional honeycomb lattice of silicon atoms is investigated and the authors show that the gap closes at a certain critical electric field, and that it is possible to generate helical zero modes anywhere in a silicene sheet by adjusting the electric field.
Abstract: Silicene is a monolayer of silicon atoms forming a two-dimensional honeycomb lattice, which shares almost every remarkable property with graphene. The low energy structure of silicene is described by Dirac electrons with relatively large spin-orbit interactions due to its buckled structure. The key observation is that the band structure is controllable by applying the electric field to a silicene sheet. In particular, the gap closes at a certain critical electric field. Examining the band structure of a silicene nanoribbon, we demonstrate that a topological phase transition occurs from a topological insulator to a band insulator with the increase of the electric field. We also show that it is possible to generate helical zero modes anywhere in a silicene sheet by adjusting the electric field locally to this critical value. The region may act as a quantum wire or a quantum dot surrounded by topological and/or band insulators. We explicitly construct the wave functions for some simple geometries based on the low-energy effective Dirac theory. These results are applicable also to germanene, that is a two-dimensional honeycomb structure of germanium.

593 citations


Journal ArticleDOI
TL;DR: In this article, the wave functions for simple geometries based on the low-energy effective Dirac theory were constructed for a silicene nanoribbon and showed that a topological phase transition occurs from a topologically topological insulator to a band insulator with an increase of electric field.
Abstract: Silicene is a monolayer of silicon atoms forming a two-dimensional (2D) honeycomb lattice and shares almost all the remarkable properties of graphene. The low-energy structure of silicene is described by Dirac electrons with relatively large spin–orbit interactions owing to its buckled structure. A key observation is that the band structure can be controlled by applying an electric field to a silicene sheet. In particular, the gap closes at a certain critical electric field. Examining the band structure of a silicene nanoribbon, we show that a topological phase transition occurs from a topological insulator to a band insulator with an increase of electric field. We also show that it is possible to generate helical zero modes anywhere in a silicene sheet by adjusting the electric field locally to this critical value. The region may act as a quantum wire or a quantum dot surrounded by topological and/or band insulators. We explicitly construct the wave functions for some simple geometries based on the low-energy effective Dirac theory. These results are also applicable to germanene, which is a 2D honeycomb structure of germanium.

573 citations


Journal ArticleDOI
TL;DR: In this article, the feasibility of inkjet-printed passive components such as resistor, capacitor, and inductor were demonstrated on a polyimide (PI) substrate with various functional inks.

141 citations


Journal ArticleDOI
TL;DR: This work determines the drag current of two metallic layers separated by a ferromagnetic insulator layer by using the semiclassical Boltzmann approach with proper boundary conditions of electrons and magnons at the metal-FI interface.
Abstract: In a semiconductor heterostructure, the Coulomb interaction is responsible for the electric current drag between two 2D electron gases across an electron impenetrable insulator. For two metallic layers separated by a ferromagnetic insulator (FI) layer, the electric current drag can be mediated by a nonequilibrium magnon current of the FI. We determine the drag current by using the semiclassical Boltzmann approach with proper boundary conditions of electrons and magnons at the metal-FI interface.

135 citations


Journal ArticleDOI
TL;DR: In this article, the effect of surface charges on dc flashover characteristics of a composite polymeric insulator is studied by means of experiments and theoretical calculations, and it was revealed that negative deposited surface charges led to an enhancement of the flashover performance whereas positive ones reduced the voltage level.
Abstract: Effect of surface charges on dc flashover characteristics of a composite polymeric insulator is studied by means of experiments and theoretical calculations The considered insulator consisted of a glass fiber reinforced epoxy core covered with a layer of silicone rubber and terminated by metallic electrodes with rounded smooth edges In the experiments, the insulator surface was charged by external corona while keeping the electrodes grounded and different charging levels were realized by varying its intensity A series of disruptive discharge tests were carried out on the charged insulator under negative dc voltages It was revealed that negative deposited surface charges led to an enhancement of the flashover performance whereas positive ones reduced the flashover voltage level A theoretical model has been developed and utilized for analyzing the experimental results In the model, surface charge density profiles deduced from measured surface potential distributions were used as boundary conditions for calculations of electric fields The measured and calculated flashover voltages were found to be in agreement indicating that the observed variations in the flashover characteristics could be attributed to the modifications of the electric field produced by the surface charges

126 citations


Journal ArticleDOI
TL;DR: In this paper, the stationary resistive field distribution on the gas-solid interface along epoxy resin insulators is theoretically and experimentally investigated, and the results are compared to simulations, in which the electric conductivity of the gas is assumed to be constant.
Abstract: The stationary resistive field distribution on the gas-solid interface along epoxy resin insulators is theoretically and experimentally investigated. Due to the phenomenon that the charge carriers necessary for the conduction process originate from natural ionization and a constant generation rate is assumed, the resulting electric conductivity of gases under dc voltage stress is nonlinearly depending on the field strength. A simulation model which considers the relevant characteristic is used to calculate the electric field in gas-solid insulation systems. The influence of the ion pair generation rate of the gas, the electric field strength and the surface conductivity of an insulator on the resistive field distribution is investigated. The results are compared to simulations, in which the electric conductivity of the gas is assumed to be constant. The simulations are verified by measurements of the surface potential along an epoxy resin insulator under dc voltage.

105 citations


Journal ArticleDOI
TL;DR: In this paper, the optical response of silicene and similar materials, such as germanene, in the presence of an electrically tunable band gap for variable doping was investigated.
Abstract: We investigate the optical response of silicene and similar materials, such as germanene, in the presence of an electrically tunable band gap for variable doping. The interplay of spin-orbit coupling, due to the buckled structure of these materials, and a perpendicular electric field gives rise to a rich variety of phases: a topological or quantum spin Hall insulator, a valley-spin-polarized metal, and a band insulator. We show that the dynamical conductivity should reveal signatures of these different phases which would allow for their identification along with the determination of parameters such as the spin-orbit energy gap. We find an interesting feature where the electric field tuning of the band gap might be used to switch on and off the Drude intraband response. Furthermore, in the presence of spin-valley coupling, the response to circularly polarized light as a function of frequency and electric field tuning of the band gap is examined. Using right- and left-handed circular polarization, it is possible to select a particular combination of spin and valley index. The frequency for this effect can be varied by tuning the band gap.

103 citations


Journal ArticleDOI
TL;DR: In this paper, a fractured 500 kV ac composite insulator, whose fracture characteristics differ significantly from those of brittle fracture, is analyzed in order to identify the aging mechanisms involved and their causes.
Abstract: In this paper, a fractured 500 kV ac composite insulator, whose fracture characteristics differ significantly from those of brittle fracture, is analyzed in order to identify the aging mechanisms involved and their causes. Several sheath punctures occurred along the insulator which apparently originated from inside the insulator. Removal of the sheath revealed weak adhesion as well as tracking along the sheath-core interface. Weak microscopic as well as macroscopic interfaces were indicated by the insulator's weak performance in the water diffusion and dye penetration test according to IEC 62217. The core material was analyzed by means of FTIR identifying glass corrosion, ion exchange and hydrolysis as major degradation mechanisms. Based on the results of analysis, a water induced aging process is proposed and recommendations for online monitoring of composite insulators with respect to interfacial aging are given.

93 citations


Journal ArticleDOI
TL;DR: In this article, the authors used an inclined plane (IP) tracking and erosion test under both positive and negative dc voltages for silicone rubber samples filled with micron and nano-sized particles to understand the phenomena occurring during such tests.
Abstract: In order to improve the tracking and erosion performance of outdoor polymeric silicone rubber (SR) insulators used in HV power transmission lines, micron sized inorganic fillers are usually added to the base SR matrix. In addition, insulators used in high voltage dc transmission lines are designed to have increased creepage distance to mitigate the tracking and erosion problems. ASTM D2303 standard gives a procedure for finding the tracking and erosion resistance of outdoor polymeric insulator weathershed material samples under laboratory conditions for ac voltages. In this paper, inclined plane (IP) tracking and erosion tests similar to ASTM D2303 were conducted under both positive and negative dc voltages for silicone rubber samples filled with micron and nano sized particles to understand the phenomena occurring during such tests. Micron sized Alumina Trihydrate (ATH) and nano sized alumina fillers were added to silicone rubber matrix to improve the resistance to tracking and erosion. The leakage current during the tests and the eroded mass at the end of the tests were monitored. Scanning Electron Microscopy (SEM) and Energy dispersive Xray (EDX) studies were conducted to understand the filler dispersion and the changes in surface morphology in both nanocomposite and microcomposite samples. The results suggest that nanocomposites performed better than microcomposites even for a small filler loading (4%) for both positive and negative dc stresses. It was also seen that the tracking and erosion performance of silicone rubber is better under negative dc as compared to positive dc voltage. EDX studies showed migration of different ions onto the surface of the sample during the IP test under positive dc which has led to an inferior performance as compared to the performance under negative dc.

90 citations


Journal ArticleDOI
TL;DR: Low voltage operation minimizes Joule heating effects that have limited previous systems, opening up the possibility for new biological applications of iDEP.
Abstract: Insulator-based dielectrophoresis (iDEP) is a very promising technique for sorting microparticles based on their electrical properties. The need for microfabricated electrode arrays is eliminated by using constrictions in a microchannel to induce large electric field gradients. In this work, micro-milling is used to build devices with three-dimensional features that exhibit very large constriction ratios. These three-dimensional insulator-based dielectrophoresis (3DiDEP) devices allow for trapping microparticles at average electric fields one order of magnitude lower than two-dimensional designs with the same footprint. Low voltage operation minimizes Joule heating effects that have limited previous systems, opening up the possibility for new biological applications of iDEP.

Journal ArticleDOI
TL;DR: In this paper, an approach to high field control, particularly in the areas near the high voltage (HV) and ground terminals of an outdoor insulator, is proposed using a nonlinear grading material; Zinc Oxide (ZnO) microvaristors compounded with other polymeric materials to obtain the required properties and allow easy application.
Abstract: An approach to high field control, particularly in the areas near the high voltage (HV) and ground terminals of an outdoor insulator, is proposed using a nonlinear grading material; Zinc Oxide (ZnO) microvaristors compounded with other polymeric materials to obtain the required properties and allow easy application. The electrical properties of the microvaristor compounds are characterised by a nonlinear field-dependent conductivity. This paper describes the principles of the proposed field-control solution and demonstrates the effectiveness of the proposed approach in controlling the electric field along insulator profiles. A case study is carried out for a typical 11 kV polymeric insulator design to highlight the merits of the grading approach. Analysis of electric potential and field distributions on the insulator surface is described under dry clean and uniformly contaminated surface conditions for both standard and microvaristor-graded insulators. The grading and optimisation principles to allow better performance are investigated to improve the performance of the insulator both under steady state operation and under surge conditions. Furthermore, the dissipated power and associated heat are derived to examine surface heating and losses in the grading regions and for the complete insulator. Preliminary tests on inhouse prototype insulators have confirmed better flashover performance of the proposed graded insulator with a 21 % increase in flashover voltage.

Journal ArticleDOI
TL;DR: It is shown that topological quantum phase transitions are driven by external electric fields in thin films of Sb2Te3, and the band topology is identified by directly calculating the invariant from electronic wave functions.
Abstract: Using first-principles calculations, we show that topological quantum phase transitions are driven by external electric fields in thin films of Sb(2)Te(3). The film, as the applied electric field normal to its surface increases, is transformed from a normal insulator to a topological insulator or vice versa depending on the film thickness. We identify the band topology by directly calculating the Z(2) invariant from electronic wave functions. The dispersion of edge states is also found to be consistent with the bulk band topology in view of the bulk-boundary correspondence. We present possible applications of the topological phase transition as an on/off switch of the topologically protected edge states in nano-scale devices.

Journal ArticleDOI
TL;DR: In this article, a unified model for low resistivity metal-insulator-semiconductor (M-I-S) ohmic contact was developed for low conduction band offset.
Abstract: A comprehensive, physics-based unified model is developed for study of low resistivity metal-insulator-semiconductor (M-I-S) ohmic contact. Reduction in metal-induced gap state density and Fermi unpinning in semiconductor as a function of insulator thickness is coupled with electron transport including tunnel resistance through the metal-insulator-semiconductor (M-I-S) system to calculate specific contact resistivity at each insulator thickness for n-Si, n-Ge, and n-InGaAs. Low conduction band offset results in ∼1×10−9 Ω−cm2 contact resistivity with TiO2 insulator on n-Si, ∼7×10−9 Ω−cm2 can be achieved using TiO2 and ZnO on n-Ge, and ∼6×10−9 Ω−cm2 can be achieved with CdO insulator on n-InGaAs, which meet the sub-22nm CMOS requirements.

Patent
12 Jan 2012
TL;DR: In this article, a bus bar is inserted into a through-hole formed in the housing 30 of the ECU to prevent the bus bar from contacting a housing of an electronic control unit and electronic parts.
Abstract: PROBLEM TO BE SOLVED: To provide an electric power steering device which prevents a bus bar of an electric motor from contacting a housing of an electronic control unit (ECU) and electronic parts.SOLUTION: The electric motor 18 for assisting the steering includes the bus bar 32 extended from the electric motor 18. The ECU, which controls the drive of the electric motor 18, includes a housing 30 and a power source module 31 consisting of an insulator provided in the ECU, while the power source module 31 includes a power supply bus bar 33 extended from the power source module 31. On the power source module 31, an extension part 35 is also formed that contacts the electric motor 18. This extension part 35 is inserted into a through-hole formed in the housing 30 of the ECU. In the extension part, a bus bar insertion hole 34, through which the bus bar 32 extended from the electric motor 18 is passed, is formed.

Journal ArticleDOI
TL;DR: In this paper, a vertical power MOSFET with an interdigitated drift region using high- $k$ (Hk) insulator was studied and it was shown that the specific on-resistance of the Hk-MOSET is comparable to that of the superjunction MOSET with the same breakdown voltage.
Abstract: A vertical power MOSFET with an interdigitated drift region using high- $k$ (Hk) insulator (Hk-MOSFET) is studied. Due to the fact that most of the electric displacement lines produced by the charges of the depleted drift region under reverse bias are through the Hk insulator, much heavier doping concentration can be used in the drift region when comparing with a conventional MOSFET with the same breakdown voltage. It is shown that the specific on-resistance of the Hk-MOSFET is comparable to that of the superjunction MOSFET (SJ-MOSFET) with the same breakdown voltage. The turn-on and turn-off times are found to be little longer than those of the conventional MOSFET and the SJ-MOSFET. The theoretical results of the electrical characteristics are in good agreement with the results from numerical simulations.

Journal ArticleDOI
TL;DR: In this article, the spin Chern number of a monolayer of silicon atoms forming a honeycomb lattice is analyzed and the origin of pseudospin meron in the momentum space is found.
Abstract: Silicene is a monolayer of silicon atoms forming a honeycomb lattice. The lattice is actually made of two sublattices with a tiny separation. Silicene is a topological insulator, which is characterized by a full insulating gap in the bulk and helical gapless edges. It undergoes a phase transition from a topological insulator to a band insulator by applying external electric field. Analyzing the spin Chern number based on the effective Dirac theory, we find the origin to be a pseudospin meron in the momentum space. The peudospin degree of freedom arises from the two-sublattice structure. Our analysis makes clear the mechanism how a phase transition occurs from a topological insulator to a band insulator under increasing electric field. We propose a method to determine the critical electric field with the aid of diamagnetism of silicene. Diamagnetism is tunable by the external electric field, and exhibits a singular behaviour at the critical electric field. Our result is important also from the viewpoint of cross correlation between electric field and magnetism. Furthermore, nano-electromechanic devices transforming electric force to mechanical force may be feasible. Our finding will be important for future electro-magnetic correlated devices.

Journal ArticleDOI
TL;DR: In this article, a leakage current that is continuous, periodic, or increasing with time is one consideration in the performance of insulators in pollution zones, whereas the maximum permissible levels of leakage current at flashover, which is considerably different for each insulator profile, is another consideration.
Abstract: Monitoring of leakage currents on various types of insulators, in the field and in laboratory tests, has provided a much broader perspective on the performance of outdoor insulators in various pollution zones. The technique can be effective for corrective maintenance of transmission lines, provided the type of pollutant and the critical leakage currents are analyzed periodically. A leakage current that is continuous, periodic, or increasing with time is one consideration in the performance of insulators in pollution zones, whereas the maximum permissible levels of leakage current at flashover, which is considerably different for each insulator profile, is another consideration. What this means is that insulators showing lower leakage currents will not necessarily have the best operating performance. The insulator profile affects the accumulation of pollutants, which defines their pollution performance, and control of the leakage current by the insulator design depends largely on the type of pollutant. As a result, there is no unique solution, and leakage current values with flashover risk from laboratory tests for various types of insulators must be determined by using the type of pollutant in the field. This combination of strategies will provide an effective means of ensuring reliable transmission line operation in pollution zones.

Journal ArticleDOI
TL;DR: Aiming at porcelain long rod, disc type and composite long rod UHVDC insulators, the authors presents a comparison of their dc pollution flashover performances and an analysis of arcing behavior at high altitudes (1970m).
Abstract: Aiming at porcelain long rod, disc type and composite long rod UHVDC insulators, this paper presents a comparison of their dc pollution flashover performances and an analysis of arcing behavior at high altitudes (1970m). The solid layer method was used in artificial pollution tests, in which sodium chloride and kaolin powder were used to simulate conductive and inert materials. The insulators were wetted by steam fog in a fog chamber. The 50% flashover voltage (U50%) was measured with the up-and-down method. According to the test results, the three types of insulators are similar in the characteristic exponent which characterizes influence of the salt deposit density on the flashover voltage. Due to lower utilization ratio of leakage distances, pollution flashover voltage gradient for the porcelain long rod insulators is lower than that for the disc type insulators. Whereas covered with Room Temperature Vulcanized (RTV) silicone rubber coatings on the trunk surfaces, the porcelain long rod insulator is much superior to the disc type insulators in pollution flashover voltage gradient. The dc pollution flashover performance and the utilization ratio of leakage distances for the composite long rod insulators are much better than those for the other two types of insulators, which are induced by the special configuration of composite long rod insulators.

Journal ArticleDOI
TL;DR: In this article, a new inspection robot system for live-line suspension insulator strings was developed to prevent an insulator failure in 345-kV power transmission lines, which adopted a wheel-leg moving mechanism.
Abstract: A new inspection robot system for live-line suspension insulator strings was developed to prevent an insulator failure in 345-kV power transmission lines. Compared with the existing inspection robots, this robot structure is very simple, small-sized, lightweight, and more superior in insulation by adopting a wheel-leg moving mechanism. In addition, the robot measures the distribution voltage of an insulator together with its insulation resistance, thereby providing more information for its analysis and diagnosis. Moreover, a manual tool for its installation and removal is presented. Its effectiveness was confirmed through experiments, including a live-line test.

Journal ArticleDOI
Genyo Ueta, Junichi Wada, S. Okabe, Makoto Miyashita1, C. Nishida1, Mitsuhito Kamei1 
TL;DR: In this paper, an estimation method using electric field analysis is used for designing the defect shape and that the breakdown voltage depends on the three-dimensional shape of the defect, and the puncture properties and PD characteristics of artificial micro-defects of cracks, voids, and delaminations produced using an accurate estimation technique and precise production control were investigated and described.
Abstract: Gas insulated switchgear (GIS) has been widely applied in power equipment since the late 1960s due to its reliability and compactness. Because epoxy insulators in GIS are important insulation components that affect the dielectric withstand level and the equipment lifetime, high voltage tests and sensitive partial discharge (PD) tests have been carried out on them in the factory. If a latent defect occurs inside an actual epoxy insulator, its size is predicted to be small, such as a micro-defect, because it will have passed rigorous tests and multiple inspections at the factory. Although many studies have clarified the fundamental phenomena of deterioration caused by PD occurring due to defects in inner epoxy, little is known about the actual size of such defects and their effect on insulation properties. Therefore, to assess the risks associated with aging GIS equipment, it is essential to understand the actual size of latent defects in inner epoxy insulators of GIS and the impact the defects have on the insulation performance. The puncture properties and PD characteristics of artificial micro-defects of cracks, voids, and delaminations produced using an accurate estimation technique and precise production control were investigated and are described. The results suggest that an estimation method using electric field analysis is useful for designing the defect shape and that the breakdown voltage depends on the three-dimensional shape of the defect. Techniques for accurate estimation of small defects in epoxy resin and stable production of micro-defects have thus been achieved.

Journal ArticleDOI
TL;DR: In this article, the surface potential distributions on a cone-type insulator are measured and the charge distributions are calculated based on the 3D field calculation by the surface charge method.
Abstract: In order to study the phenomenon of surface charge accumulation on cone-type insulators, a surface charge measuring system is established, based on the electrostatic probe method. The surface potential distributions on a cone-type insulator are measured and the charge distributions are calculated based on the 3D field calculation by the surface charge method. The characteristics of charge distributions are compared under different voltage durations and voltage amplitudes. The results show that the charge accumulation comes to a steady state after 120 min. A threshold voltage effect is observed that charges seldom accumulate unless the applied voltage reaches a certain magnitude. The mechanisms of charge accumulation are discussed. The surface conduction and volume conduction do not seem to dominate the charge accumulation on the insulator. Partial discharges in gas may be the main sources of surface charges.

Journal ArticleDOI
TL;DR: In this paper, a modification of the modified Peek formula for calculating the corona inception electric field of positive dc conductor has been performed for taking into account the effect of air humidity.
Abstract: The corona on conductors is of importance for ultra-high voltage transmission Humidity in air is an important factor of affecting corona inception electric field Due to long distances of the ultra-high voltage direct current (dc) transmission, the transmission line crossing a high humidity area is inevitable, and thus the humidity should be taken into account in evaluation of the corona inception electric field of positive dc conductor In this work a modification of Peek formula of calculating the corona inception electric field of positive dc conductor has been performed for taking into account the effect of air humidity Using the modified Peek formula, the corona inception electric fields for the conductors with different radii under different humidity are calculated and compared with the reported experimental results Reasonable agreement between calculated results and the experiments is obtained, which shows that the modified Peek formula is a good one for the effective and easy calculations of the corona inception electric field of positive dc conductor under different humidity

Patent
03 Jan 2012
TL;DR: In this article, a method of forming a silicon-on-insulator (SOI) wafer substrate is described, which includes providing a handle substrate, forming a high resistivity material layer over the handle substrate and bonding a donor wafer to the top surface of the insulator layer to form the SOI wafer.
Abstract: A semiconductor structure and a method of forming the same. In one embodiment, a method of forming a silicon-on-insulator (SOI) wafer substrate includes: providing a handle substrate; forming a high resistivity material layer over the handle substrate, the high resistivity material layer including one of an amorphous silicon carbide (SiC), a polycrystalline SiC, an amorphous diamond, or a polycrystalline diamond; forming an insulator layer over the high resistivity material layer; and bonding a donor wafer to a top surface of the insulator layer to form the SOI wafer substrate.

Journal ArticleDOI
TL;DR: In this article, the authors presented a theoretical model for evaluating flashover performance of insulators under contaminated conditions, which introduced several new features when compared with existing models such as, the formation of dry bands, variations in insulator geometry and surface wettability.
Abstract: This paper presents a theoretical model for evaluating flashover performance of insulators under contaminated conditions. The model introduces several new features when compared with existing models such as, the formation of dry bands, variations in insulator geometry and surface wettability. The electric field distribution obtained from software for 3-Dimensional models along with form factor are used to determine the dimensions of the dry bands and the onset of arcing. The model draws heavily from experimental measurements of flashover voltage and surface resistance under wet conditions of porcelain and composite insulators. The model illustrates the dominant role played by the insulator shape and housing material on the flashover performance.

Journal ArticleDOI
TL;DR: In this paper, an ionic-liquid-gated electric-double-layer transistors (EDLTs) were used for controlling the surface electronic states on metallic systems, and it was shown that an electric double layer works as a nanogap capacitor with 27 (-25) MV cm-1 of electric field by applying only 1.7 V of positive (negative) gate voltage.
Abstract: Electroresistance effect was detected in a metallic thin film using ionic-liquid-gated electric-double-layer transistors (EDLTs). We observed reversible modulation of the electric resistance of a Au thin film. In this system, we found that an electric double layer works as a nanogap capacitor with 27 (-25) MV cm-1 of electric field by applying only 1.7 V of positive (negative) gate voltage. The experimental results indicate that the ionic-liquid-gated EDLT technique can be used for controlling the surface electronic states on metallic systems.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the distribution of charges on surfaces of polymeric cylindrical insulators that emerge due to dc corona discharges in surrounding air and by stressing with dc voltage.
Abstract: Distributions of charges are investigated on surfaces of polymeric cylindrical insulators that emerge due to dc corona discharges in surrounding air and by stressing with dc voltage. The studied model insulator consisted of a glass fiber reinforced epoxy core covered with a sheath of silicone rubber, terminated by metallic electrodes with rounded smooth edges. Surface potential distributions were measured 1 min after completing the charging process by means of a Kelvin electrostatic probe connected to an electrostatic voltmeter. The measured surface potential profiles were utilized to calculate corresponding charge density distributions. The obtained results demonstrated significant differences in the surface charge patterns for different charging conditions, which in turn may affect flashover withstand of the insulator.

Journal ArticleDOI
TL;DR: In this article, a closed form formulation for the impedance of the metal-insulator-metal (MIM) plasmonic transmission lines by solving the Maxwell's equations is proposed.
Abstract: We propose a closed form formulation for the impedance of the metal–insulator–metal (MIM) plasmonic transmission lines by solving the Maxwell’s equations. We provide approximations for thin and thick insulator layers sandwiched between metallic layers. In the case of very thin dielectric layer, the surface waves on both interfaces are strongly coupled resulting in an almost linear dependence of the impedance of the plasmonic transmission line on the thickness of the insulator layer. On the other hand, for very thick insulator layer, the impedance does not vary with the insulator layer thickness due to the weak-coupling/decoupling of the surface waves on each metal–insulator interface. We demonstrate the effectiveness of our proposed formulation using two test scenarios, namely, almost zero reflection in T-junction and reflection from line discontinuity in the design of Bragg reflectors, where we compare our formulation against previously published results.

Journal ArticleDOI
TL;DR: In this article, the asymmetric phenomenon of the carrier conduction behavior at the high-resistance state in high electric field is investigated by current-voltage (I-V) curve fitting in the TiN/WSiOX/Pt RRAM device.
Abstract: Resistance random access memory (RRAM) is a great potential candidate for next-generation nonvolatile memory due to the outstanding memory characteristic. However, the resistance switching mechanism is still a riddle nowadays. In this letter, the switching mechanism is investigated by current-voltage (I-V) curve fitting in the TiN/WSiOX/Pt RRAM device. The asymmetric phenomenon of the carrier conduction behavior is explained at the high-resistance state in high electric field. The switching behavior is regarded to tip electric field by localizing the filament between the interface of top electrode and insulator.

Journal ArticleDOI
TL;DR: In this paper, the surface conductance of an insulating spacer is measured and the influence of surface conductivity on charge accumulation is examined both experimentally and by numerical computation.
Abstract: When a DC voltage is applied to an insulating spacer, the electric field distribution around it is determined by the resistivity of the material. Consequently, charges are accumulated on the surface of the insulator, and its breakdown voltage may become low. In this paper, the charge density distribution of the insulator is measured. The measured data indicate that the surface conductance is the main factor in charge accumulation. Therefore, the conductivity of the insulator is also measured, and the influence of the surface conductivity on charge accumulation is examined both experimentally and by numerical computation. It is confirmed that nonuniformity of surface conductivity is responsible for charge accumulation and the conductivity of the insulator in atmospheric-pressure SF6 is estimated to be . © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(2): 29–36, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22272