On the compact modelling of Si nanowire and Si nanosheet MOSFETs

2021 ◽  
Author(s):  
Antonio Cerdeira ◽  
Magali Estrada ◽  
Marcelo Antonio Pavanello
Keyword(s):  
Electric Field ◽  
Electron Concentration ◽  
Current Density ◽  
Electric Field Distribution ◽  
Double Gate ◽  
Si Nanowire ◽  
Circuit Simulator ◽  
Aspect Ratios ◽  
Good Agreement ◽  
Tcad Simulations

Abstract In this paper, 3D TCAD simulations are used to show that the electron concentration, current density, and electric field distribution from the interface at the lateral channels and from the top channel to the centre of the silicon wire, in Nanowire and Nanosheet structures, are practically same. This characteristic makes possible to consider that the total channel width for these structures is equal to the perimeter of the transistor sheet, allowing to extend the application of the Symmetric Doped Double-Gate Model (SDDGM) model to Nanowires and Nanosheets MOSFETs, with no need to include new parameters. The Model SDDGM is validated for this application using several measured and simulated structures of Nanowires and Nanosheets transistors, with different aspect ratios of fin width and fin height, showing very good agreement between measured or simulated characteristics and modelled. SDDGM is encoded in Verilog-A language and implemented in SmartSPICE circuit simulator.

scholarly journals Analysis of Electric Field and Current Density for Different Electrode Configuration of XLPE Insulation

2018 ◽  
Vol 7 (3.36) ◽  
pp. 127 ◽  
Author(s):  
Nishanthi Sunthrasakaran ◽  
Nor Akmal Mohd Jamail ◽  
Qamarul Ezani Kamarudin ◽  
Sujeetha Gunabalan
Keyword(s):  
Electric Field ◽  
Power System ◽  
Field Distribution ◽  
High Voltage ◽  
Current Density ◽  
Electric Field Distribution ◽  
Electrical Power ◽  
High Electric Field ◽  
Electrode Configuration ◽  
Maximum Electric Field

The most important aspect influencing the circumstance and characteristics of electrical discharges is the distribution of electric field in the gap of electrodes. The study of discharge performance requires details on the variation of maximum electric field around the electrode. In electrical power system, the insulation of high voltage power system usually subjected with high electric field. The high electric field causes the degradation performance of insulation and electrical breakdown start to occur. Generally, the standard sphere gaps widely used for protective device in electrical power equipment. This project is study about the electric field distribution and current density for different electrode configuration with XLPE barrier. Hence, the different electrode configuration influences the electric field distribution. This project mainly involves the simulation in order to evaluate the maximum electric field for different electrode configuration. Finite Element Method (FEM) software has been used in this project to perform the simulation. This project also discusses the breakdown characteristics of the XLPE. The accurate evaluation of electric field distribution and maximum electric field is an essential for the determination of discharge behavior of high voltage apparatus and components. The degree of uniformity is very low for pointed rod-plane when compared to other two electrode configurations. The non- uniform electric distribution creates electrical stress within the surface of dielectric barrier. As a conclusion, when the gap distance between the electrodes increase the electric field decrease.  

scholarly journals On the question of using solid electrodes in the electrolysis of cryolite-alumina melts. Part 3. Electric field distribution on the electrodes

2021 ◽  
Vol 25 (2) ◽  
pp. 235-251
Author(s):  
E. S. Gorlanov ◽  
A. A. Polyakov
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Edge Effect ◽  
Current Density ◽  
Molten Salts ◽  
Functional Relationship ◽  
Electric Field Distribution ◽  
Chemical Inhomogeneity ◽  
Electrolytic Process ◽  
Solid Electrodes

The aim of this work is to identify the theoretical limitations of molten salts electrolysis using solid electrodes to overcome these limitations in practice. We applied the theory of electric field distribution on the electrodes in aqueous solutions to predict the distribution of current density and potential on the polycrystalline surface of electrodes in molten salts. By combining the theoretical background of the current density distribution with the basic laws of potential formation on the surface of the electrodes, we determined and validated the sequence of numerical studies of electrolytic processes in the pole gap. The application of the method allowed the characteristics of the current concentration edge effect at the periphery of smooth electrodes and the distribution of current density and potential on the heterogeneous electrode surface to be determined. The functional relationship and development of the electrolysis parameters on the smooth and rough surfaces of electrodes were established by the different scenario simulations of their interaction. It was shown that it is possible to reduce the nonuniformity of the current and potential distribution on the initially rough surface of electrodes with an increase in the cathode polarisation, alumina concentration optimisation and melt circulation. It is, nonetheless, evident that with prolonged electrolysis, physical and chemical inhomogeneity can develop, nullifying all attempts to stabilise the process. We theoretically established a relationship between the edge effect and roughness and the distribution of the current density and potential on solid electrodes, which can act as a primary and generalising reason for their increased consumption, passivation and electrolytic process destabilisation in standard and low-melting electrolytes. This functional relationship can form a basis for developing the methods of flattening the electric field distribution over the anodes and cathodes area and, therefore, stabilising the electrolytic process. Literature overview, laboratory tests and theoretical calculations allowed the organising principle of a stable electrolytic process to be formulated -the combined application of elliptical electrodes and the electrochemical micro-borating of the cathodes. Practical verification of this assumption is one direction for further theoretical and laboratory research.

The Whole Simulation Analysis and Measurement of the Power Frequency Electric Field in 500kV Substation

2014 ◽  
Vol 672-674 ◽  
pp. 837-841
Author(s):  
Luo Peng ◽  
Li Yong Ming
Keyword(s):  
Electric Field ◽  
Electric Field Distribution ◽  
Simulation Analysis ◽  
Simulation Method ◽  
Rapid Analysis ◽  
Charge Simulation Method ◽  
Power Frequency ◽  
Frequency Electric Field ◽  
Distribution Of Power ◽  
Good Agreement

An improved Charge Simulation Method (CSM) is proposed in this paper. Based on this method, the model of the overall 500kV substation is established, and then the power frequency electric field in substation at the height of the 1.5mabovethegroundis simulated and calculated. Specifically, these on 500kV switch yard in the station are simulated and analysis. The results show that the simulation results are in good agreement with the actual substation measured results, which is proved the correctness of the model and the algorithm. This paper provides an effective method for the rapid analysis of the distribution of power frequency electric field in ultra-high-voltage substation, and also can use the method to study the effects of electric field distribution factors in substation.

scholarly journals Time-Dependent Electric Field Distribution in Layered Paper-Oil Insulation

2019 ◽  
pp. 58-63 ◽  
Author(s):  
Gunnar Håkonseth ◽  
Erling Ildstad
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
Electric Fields ◽  
Current Density ◽  
Test Object ◽  
Dielectric Response ◽  
Electric Field Distribution ◽  
Time Dependent ◽  
Polarization Current ◽  
Dependent Polarization

Layered paper–oil insulation is used in several types of HVDC equipment. In order to better understand breakdown mechanisms and optimize the design, it is important to understand the electric field distribution in the insulation. In the present work, a test object with such insulation has been modeled as a series connection of oil and impregnated paper. The permittivity, conductivity, and the dielectric response function has been measured for impregnated paper and oil separately and used as parameters in a dielectric response model for the layered insulation system. A system of differential equations has been established describing the voltages across each material, i.e. across each layer of the test object. These equations have been solved considering a DC step voltage across the whole test object. Based on this, the time-dependent electric field in each material as well as the time-dependent polarization current density in the test object have been calculated. The calculated polarization current density was found to agree well with the measured polarization current density of the test object. This indicates that application of dielectric response theory gives a good estimate of the time-dependent electric field distribution in layered insulation systems. The results show that 90 % of the change from initial values to steady-state values for the electric fields has occurred within the first 35 minutes after the voltage step. This applies to the electric fields in both of the materials of the examined test object at a temperature of 323 K.

Effect of Electric Field Distribution Generated in a Microspace on Pool Boiling Heat Transfer

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Ichiro Kano
Keyword(s):  
Electric Field ◽  
Traveling Wave ◽  
Electric Field Distribution ◽  
Pool Boiling ◽  
Heating Surface ◽  
Wave Model ◽  
Nucleate Boiling ◽  
Working Fluid ◽  
Helmholtz Instability ◽  
Good Agreement

This study describes the effect of an electric field on nucleate boiling and critical heat flux (CHF) in pool boiling. A dielectric liquid of AE-3000 was used as the working fluid. A heating surface was polished to a surface roughness of 0.05 μm. A microsized electrode, in which slits were provided, was designed to generate a nonuniform electric field and produce electrohydrodynamic (EHD) effects with the application of high dc voltages. The obtained results confirmed CHF enhancement as the EHD effects increased CHF to 86.2 W/cm2 with a voltage of −3000 V, which was four times greater than pool boiling in the absence of the electrode. The usual traveling wave on the bubble interface, induced by the Kelvin–Helmholtz instability, was modified by adding the EHD effects. The traveling wave model exhibits the essential features of the phenomenon and shows good agreement with the experimental data.

scholarly journals 3D modeling of a superconducting dynamo-type flux pump

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Asef Ghabeli ◽  
Enric Pardo ◽  
Milan Kapolka
Keyword(s):  
Electric Field ◽  
3D Model ◽  
Precise Measurement ◽  
Electric Field Distribution ◽  
Three Dimensional ◽  
Working Mechanism ◽  
Voltage Generation ◽  
The Impact ◽  
Good Agreement ◽  
Flux Pump

AbstractHigh temperature superconducting (HTS) dynamos are promising devices that can inject large DC currents into the winding of superconducting machines or magnets in a contactless way. Thanks to this, troublesome brushes in HTS machines or bulky currents leads with high thermal losses will be no longer required. The working mechanism of HTS dynamo has been controversial during the recent years and several explanations and models have been proposed to elucidate its performance. In this paper, we present the first three-dimensional (3D) model of an HTS flux pump, which has good agreement with experiments. This model can be beneficial to clarify the mechanism of the dynamo and pinpoint its unnoticed characteristics. Employing this model, we delved into the screening current and electric field distribution across the tape surface in several crucial time steps. This is important, since the overcritical screening current has been shown to be the reason for flux pumping. In addition, we analyzed the impact of both components of electric field and screening current on voltage generation, which was not possible in previous 2D models. We also explored the necessary distance of voltage taps at different airgaps for precise measurement of the voltage across the tape in the dynamo.

Space Charge Effects Due to Near Contact Non-Uniform Electric Fields in Semi-Insulating GaAs

1992 ◽  
Vol 261 ◽  
Author(s):  
Narbeh Derhacobian ◽  
Nancy M. Haegel
Keyword(s):  
Theoretical Model ◽  
Electric Field ◽  
Electric Fields ◽  
Power Law ◽  
Current Density ◽  
Charge Effects ◽  
Constant Bias ◽  
Contact Field ◽  
Minority Carriers ◽  
Good Agreement

ABSTRACTVariable length semi-insulating GaAs p+-υ-n+ diodes are used to investigate the influence of near contact electric field non-uniformities on the injection of minority carriers. The results show that despite the presence of highly linear IV characteristics, significant nonuniformities in the electric field dominate the device response. The current density through the device is shown to depend on the device length with a power law J ∞ (L)1.0 at a constant bias. The experimental results are compared, with good agreement, to a theoretical model which treats semi-insulating GaAs as a trap-dominated relaxation semiconductor. Electroabsorption measurements are used to observe the slow transients associated with the appearance of near contact field nonuniformities.

scholarly journals Numerical modelling of the thermospheric and ionospheric effects of magnetospheric processes in the cusp region

1996 ◽  
Vol 14 (12) ◽  
pp. 1343-1355 ◽  
Author(s):  
A. A. Namgaladze ◽  
A. N. Namgaladze ◽  
M. A. Volkov
Keyword(s):  
Electric Field ◽  
Electron Concentration ◽  
Current Density ◽  
Electron Flux ◽  
Meridional Wind ◽  
Electron Precipitation ◽  
Ionospheric Effects ◽  
Cusp Region ◽  
Field Aligned Current ◽  
Atmospheric Gravity

Abstract. The thermospheric and ionospheric effects of the precipitating electron flux and field-aligned-current variations in the cusp have been modelled by the use of a new version of the global numerical model of the Earth's upper atmosphere developed for studies of polar phenomena. The responses of the electron concentration, ion, electron and neutral temperature, thermospheric wind velocity and electric-field potential to the variations of the precipitating 0.23-keV electron flux intensity and field-aligned current density in the cusp have been calculated by solving the corresponding continuity, momentum and heat balance equations. Features of the atmospheric gravity wave generation and propagation from the cusp region after the electron precipitation and field-aligned current-density increases have been found for the cases of the motionless and moving cusp region. The magnitudes of the disturbances are noticeably larger in the case of the moving region of the precipitation. The thermospheric disturbances are generated mainly by the thermospheric heating due to the soft electron precipitation and propagate to lower latitudes as large-scale atmospheric gravity waves with the mean horizontal velocity of about 690 m s–1. They reveal appreciable magnitudes at significant distances from the cusp region. The meridional-wind-velocity disturbance at 65° geomagnetic latitude is of the same order (100 m s–1) as the background wind due to the solar heating, but is oppositely directed. The ionospheric disturbances have appreciable magnitudes at the geomagnetic latitudes 70°–85°. The electron-concentration and -temperature disturbances are caused mainly by the ionization and heating processes due to the precipitation, whereas the ion-temperature disturbances are influence strongly by Joule heating of the ion gas due to the electric-field disturbances in the cusp. The latter strongly influence the zonal- and meridional-wind disturbances as well via the effects of ion drag in the cusp region. The results obtained are of interest because of the location of the EISCAT Svalbard Radar in the cusp region and the associated observations at lower latitudes that will be possible using the existing EISCAT UHF and VHF radars. The paper makes predictions for both these regions, and these predictions will be tested by joint observations by ESR, EISCAT UHF/VHF and other ground-based ionosphere/thermosphere observations.

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