Search query: alternative current conduct conductivity

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abstract: Transparent conductive oxides (TCOs) are semiconductor like materials that exhibit high electrical conductivity and high optical transparency combined. They are adopted in various applications ranging from gas sensors, to electrochromic windows or photovoltaic cells. Indium based TCOs represent the industry standard. Nevertheless, indium is among the less abundant elements in the earth crust and forecasts based on its current consumption recommend an urgent need to replace it. Tin based TCOs are a promising alternative, since their optoelectronic characteristics mimic the ones of indium based materials. This thesis aims to investigate the link between opto electronic and microstructural properties of tin dioxide and zinc tin oxide (ZTO) with a composition Zn0.05Sn0.30O0.65 and their stability when submitted to thermal treatments. Indeed, lots of practical applications require the TCO to operate in high temperature conditions. To conduct this study, a combination of analytical techniques, such as transmission electron microscopy (TEM) energy dispersive X ray spectroscopy (EDX) X ray diffraction (XRD) electron paramagnetic resonance (EPR) and differential scanning calorimetry (DSC) as well as optoelectronic measurements were employed. Amorphous SnO2 and ZTO were deposited by RF sputtering and annealed up to 1050 *C in different atmospheres. The influence of annealing temperature and atmosphere were decoupled and led us to an in depth comprehension of the mechanisms governing the opto electronic properties of both materials. When annealed in air, between room temperature and 300 *C, ZTO exhibits increased mobility and carrier concentration with respect to the as deposited state. This increase, investigated with DSC, was ascribed to a structural relaxation that allows point defects to release electrons in conduction band. Between 300 *C and 500 *C atmospheric oxygen passivates oxygen vacancies, drastically decreasing the carrier concentration and therefore causing a large drop of the conductivity. EPR experiments allowed to ascribe the drop in conductivity to the decrease of
author_names: Federica Landucci
title: A multi technique approach to study the microstructural properties of tin based transparent conductive oxides
year: 2019

abstract: Abstract The Beerkan method along with BEST algorithms is an alternative technique to conventional laboratory or field measurements for rapid and low cost estimation of soil hydraulic properties. The Beerkan method is simple to conduct but requires an operator to repeatedly pour known volumes of water through a ring positioned at the soil surface. A cheap infiltrometer equipped with a data acquisition system was recently designed to automate Beerkan infiltration experiments. In this paper, the current prototype of the automated infiltrometer was tested to validate its applicability to the Beerkan infiltration experiment under several experimental circumstances. In addition, the accuracy of the estimated saturated soil hydraulic conductivity, Ks, and sorptivity, S, was assessed by applying different BEST algorithms to the data obtained with the infiltrometer. At this purpose, both analytically generated and real experimental data were used. The analytical assessment showed that the use of the infiltrometer along with BEST methods could lead to accurate estimates of the considered soil properties in most cases, which validated the design of the infiltrometer and its combination with BEST algorithms. Loamy soils and high initial water contents led to misestimating Ks and S or to failure of BEST algorithms, but advices about the infiltrometer design were developed to alleviate such problems. A comparison between the automated procedure and the original BEST procedure was made at three field sites in Sicily (Italy) Other experiments were carried out in an infiltration basin located in the pumping well field of Crepieux Charmy (Lyon, France) in order to assess the ability of the automated infiltrometer to check clogging effects on Ks. The experiments showed that the automatic data collection increased measurement speed, allowed a more efficient data handling and analysis, and reduced sensitivity of the calculated hydraulic parameters on the applied BEST algorithm.
author_names: Simone Di Prima

Laurent Lassabatere

Vincenzo Bagarello

Massimo Iovino

Rafael Angulo-Jaramillo
title: Testing a new automated single ring infiltrometer for Beerkan infiltration experiments
year: 2016

abstract: Aquifer characterization such as hydraulic conductivity (K) is necessary due to groundwater sustainability for agriculture industry. The current method for calculating K is to conduct a pumping test or a permeability test. This study is trying to find an alternative method to obtain a K value by determining the correlation between water and aquifer resistivity which is conducted in the laboratory and field scale. The aquifer resistivity is gathered from Electrical Resistivity Tomography (ERT) and the water resistivity from direct measurement. The correlation can perform the Kozeny Carman equation, which is modified from Archie and Waxman Smits formulas, to estimate the hydraulic conductivity. The hydraulic conductivity estimation is compared with the hydraulic conductivity value from the permeability and pumping test solutions. The measurement result showed 12.63 m/day, which was similar to the permeability test with 10.3 m/day. However, the field result revealed 14.07 m/day, while the pumping test indicated 24.5 m/day. An analysis has been conducted with the fact that geological condition, grain size, and water resistivity have a significant contribution to the result. Nevertheless, the outcome of the ERT profile can be an alternative method to get an estimation of K that is more efficient, yet not offensive.
author_names: Tsania Fadilah

Lutz Gross

Ralf Schaa
title: Estimation of Aquifer Properties Using Surface Based Electrical Resistivity Tomography
year: 2018

abstract: Knowledge of the way pore geometry affects the conductivity of rocks is important for the evaluation of sedimentary rocks for hydrocarbon potential. Virtually all formation evaluation from logs, however, uses the empirical Archie equation that has never been given a satisfactory physical basis. As an alternative, we have formulated a new model based on the efficiency with which water bearing rocks conduct electric currents as determined by the conducting phase geometry. Electric current densities are not uniform throughout the conducting phase in the pore system of a rock. Numerical model studies show high current density in pore throats and low current density in nearly stagnant volumes in isolated parts of the pore system. The electrical efficiency of a rock is the ratio of the average power developed in all water bearing parts of the pore system to the power developed in a straight tube with the same length and water volume as the rock. It is inherently independent of the bulk volume of water in the ro.
author_names: David C Herrick

William D Kennedy
title: Electrical efficiency A pore geometric theory for interpreting the electrical properties of reservoir rocks
year: 1994

abstract: Due to their extremely high electron mobility alternative semiconductor materials such as Germanium (Ge) and III V materials are being investigated as channel materials for high performance NMOS [1 4] Although their small transport mass leads to high injection velocity (vinj) III V materials have a low density of states (DOS) in the valley, tending to reduce the inversion charge (Qinv) and hence reduce drive current [5 6] Furthermore, the small direct band gaps of Ge and III V materials inherently give rise to very large band to band tunneling (BTBT) leakage current compared to Si [9] They also have a high permittivity and hence are more prone to short channel effects (SCE) Although in these ultra thin channel devices quantum confinement plays a very important role, these effects were overlooked in previous studies. In III Vs, Large quantum confinement makes electrons populate and conduct in heavier L or X valleys, which other studies [5,7] by Monte Carlo method did not capture. Furthermore, increased conductivity mass in quantized sub bands due to large non parabolicity of valley has been underestimated [6 7] Quantum confinement effects also reduce BTBT leakage in ultra thin channel [9] which has not been considered in other MOSFET studies [5 8] In this work, we have thoroughly investigated Double Gate (DG) n MOSFETs with Ge (111) and III V materials (GaAs (111) InP (111) InAs (111) and InSb (111) and compared to Si (100) The simulations performed under ballistic transport take into account non parabolic full band structure, quantum confinement effects, BTBT leakage and SCE effects. Device structure and bias conditions are LG=15nm, TOX=0.7nm, TS=3 10nm and VDD=0.3 0.7V. Source and drain are assumed to be perfect absorbers. Results are shown in Figs. 1 (ION) 2 (IOFF,BTBT) and 3 (Intrinsic gate delay vs. IOFF,BTBT) The intrinsic gate delay is calculated as Q/Ieff, where Ieff is defined as, 1/2 {ID(VDD,VDD/2) ID(VDD/2,V= ID(VG,VD) The minimum achievable standby leakage by BTBT (IOFF,BTBT) is at the intersection of the BTBT leakage with the subthreshold leakage. DGFET cannot have lower leakage current than IOFF,BTBT by adjusting threshold voltage. From drive current (ION) standpoint, Ge looks very promising; it has highest ION due to its very large DOS (L valleys) and small transport. Despite of low inversion charge (Qinv) thanks to their large injection velocity (vinj) III V materials like InAs, InSb and InP can flow up to 80% larger drive current than Si. In GaAs majority of electron resides in L valleys, which makes GaAs behaves like Ge but with slightly worse ION. Intrinsic delay is strongly dependent on transport effective mass, thus III Vs always switch faster than Si by up to 6 times. Small bandgap materials such as InAs, InSb and Ge have extremely large IOFF,BTBT higher than 0.1mA/mm. Scaling TS enhances the device performance by eliminating the SCE effect and reducing BTBT leakage. IOFF,BTBT in Ge, InAs, GaAs and InSb can be reduced by over 1000x by scaling Ts to 3nm (Fig. 2) due to enlarged bandgap by quantization of sub bands. As Ts scales, ION is increased by 2.5 times (Fig. 1) but concurrently electrons become heavier, resulting in losing the advantage of III Vs over Si. Overall, among III V materials InP exhibits the best performance; high ION, short delay and low IOFF,BTBT compared Si. Ge has highest ION thanks to its large DOS and small transport effective mass, but it suffers from large BTBT leakage. If the technology let Ts scale under 5nm, IOFF,BTBT for Ge can be lowered below 0.1uA/um. Acknowledgement: This work was supported by FCRP Materials, Structures and Device Center. References: 1. S. Datta et.al, Int. Solid State IC Conf. (2004) 2. M.V. Fischetti, IEEE TED, 634 (1991) 3. R. Chau et.al. IEEE TON, 153 (2005) 4. A. Asenov et al, Microelec. Eng. 2398 (2007) 5. M.V. Fischetti et al, IEEE TED, 115 (2007) 6. M. Michielis et al, IEEE TED, 115 (2007) 7. S.E. Laux, IEEE TED, 2304 (2007) 8. K.D. Cantley et al, IEEE IEDM, 113 (2007) 9. D. Kim et al. SISPAD, 389 (2006) 10. K. Natori, J. Appl. Phys. 4879 (1994) 11. Q. Chen et al, IEEE TED. 1086 (2002) 12. E. O. Kane, J. Appl. Phys. 83 (1961)
author_names: Dong-hyun Kim

Tejas Krishnamohan

Krishna C Saraswat
title: Performance Evaluation of 15nm Gate Length Double Gate n MOSFETs with High Mobility Channels: III V, Ge and Si
year: 2008

abstract: Abstract The Na 1 x Ag x AlP 2 O 7 (x 0.4, x 0.6 and x 0.8) samples were prepared by solid state reaction technique at high temperature. The structural and electrical transport properties have been investigated. The x ray powder diffraction patterns at room temperature show that all samples are formed in single phase and crystallize in the monoclinic system with P2 1/C space group. The electrical technique was measured in the 200 Hz 5 MHz frequency range and 573 673 K temperature intervals. The impedance plot has shown semicircle arcs at different temperatures and in order to explain the impedance results, an electrical equivalent circuit has been proposed. The maximum value of conductivity achieved for this material is 3.47 x 10 6 (O cm) 1 for x 0.4, 3.12 x 10 5 (O cm) 1 for x 0.6 and 1.64 x 10 5 (O cm) 1 for x 0.8. The conductivity increases with increase in Ag substitution. The frequency dependence of alternative current (AC) conductivity is interpreted in terms of Jonscher's law. The AC conductivity is analyzed by different processes, which can be attributed to several models: the non overlapping small polaron tunneling model (NSPT) for x 0.4 and x 0.6, the correlated barrier hopping (CBH) for x 0.8. The conduction mechanism is studied with the help of Elliot's theory, and the Elliot's parameters are determined.
author_names: Y Ben Taher

Abderrazek Oueslati

Mohamed Gargouri
title: Alternative current conduction mechanisms and effect of Ag substitution on conductivity in Na1 xAgxAlP2O7 (x 0.4, x 0.6 and x 0.8) compounds
year: 2016

abstract: Abstract We present a comprehensive numerical analysis of alternative transient eddy current flowmetering methods for liquid metals. This type of flowmeter operates by tracking eddy current markers excited by the magnetic field pulses in the flow of a conducting liquid. Using a simple mathematical model, where the fluid flow is replaced by a translating cylinder, a number possible alternative measurement schemes are considered. The velocity of the medium can be measured by tracking zero crossing points and spatial or temporal extrema of the electromotive force (emf) induced by transient eddy currents in the surrounding space. Zero crossing points and spatial extrema of the emf travel synchronously with the medium whereas temporal extrema experience an initial time delay which depends on the conductivity and velocity of the medium. Performance of transient eddy current flowmetering depends crucially on the symmetry of system. Eddy current asymmetry of a few per cent makes the detection point drift with a velocity corresponding to a magnetic Reynolds number Rm 0.1 With this level of asymmetry transient eddy current flowmetering can be reliably applicable only to flows with Rm 0.1 A more accurate symmetry adjustment or calibration of flowmeters may be necessary at lower velocities.
author_names: Richard Looney

Janis Priede
title: Alternative transient eddy current flowmetering methods for liquid metals
venue: Flow Measurement and Instrumentation
year: 2019

abstract: Abstract The trimethylammonium cobalt chloride dihydrate was obtained by slow evaporation at room temperature. The behavior in accordance with temperature variation was sought. The Rietveld refinement of the X ray powder diffraction pattern led to the formation of a pure phase which crystallizes in the orthorhombic system with the Pnma space group. Three endothermic peaks at T 1 =310 K, T 2 =349 K, and T 3 =358 K were evidenced by DSC measurements. In order to characterize the phase transitions and their nature, Raman spectra were recorded in the frequency range related to the vibrations of the cations and anions (10 3600 cm 1 The results obtained show the utility of the Raman spectra to probe the changes in T 1 and then the reconstruction of new anionic parts after T 2 transition. The analysis of the line width based on the order disorder model was used to obtain information concerning the activation energy near the phase transition at T 1 A comprehensive study of the dielectric and electric modulus properties of this compound was conducted using impedance spectroscopy in the frequency range of 100 Hz to 1.3 MHz and over the temperature range of 270 K to 335 K. The analysis of Nyquist plots revealed the presence of grains, grain boundaries and the electrode effects. The modulus plots were characterized by the presence of two peaks associated with grains and grain boundaries. The temperature dependence of the electrical conductivity (s g and AC conductivity (s ac confirmed the phase transition. The AC electrical conduction in the (CH 3 3 NH]CoCl 3 *2H 2 O compound underwent two processes attributed to a hopping transport mechanism: the correlated barrier hopping model in region I and the non overlapping small polaron tunneling model proposed as a closely good model for region II.
author_names: Hela Kchaou

Khayria Karoui

Alain D F Bulou

Mohamed Tabellout

Abdallah Ben Rhaiem
title: Raman scattering and alternative current conduction mechanism of the different phase transitions in (CH3)3NH]CoCl3*2H2O
year: 2017

abstract: In vivo measurements of human brain tissue conductivity at body temperature were conducted using focal electrical currents injected through intracerebral multicontact electrodes. A total of 1,421 measurements in 15 epileptic patients (age: 28 10) using a radiofrequency generator (50 kHz current injection) were analyzed. Each contact pair was classified as being from healthy (gray matter, n 696; white matter, n 530) or pathological (epileptogenic zone, n 195) tissue using neuroimaging analysis of the local tissue environment and intracerebral EEG recordings. Brain tissue conductivities were obtained using numerical simulations based on conductivity estimates that accounted for the current flow in the local brain volume around the contact pairs (a cube with a side length of 13 mm) Conductivity values were 0.26 S/m for gray matter and 0.17 S/m for white matter. Healthy gray and white matter had statistically different median impedances (P 0.0001) White matter conductivity was found to be homogeneous as normality tests did not find evidence of multiple subgroups. Gray matter had lower conductivity in healthy tissue than in the epileptogenic zone (0.26 vs. 0.29 S/m; P 0.012) even when the epileptogenic zone was not visible in the magnetic resonance image (MRI) (P 0.005) The present in vivo conductivity values could serve to create more accurate volume conduction models and could help to refine the identification of relevant intracerebral contacts, especially when located within the epileptogenic zone of an MRI invisible lesion. Hum Brain Mapp 38:974 986, 2017. (c) 2016 Wiley Periodicals, Inc.
author_names: Laurent Koessler

Sophie Colnat-Coulbois

Thierry Cecchin

Janis Hofmanis

Jacek Dmochowski

Anthony Matthew Norcia

Louis Maillard
title: In vivo measurements of human brain tissue conductivity using focal electrical current injection through intracerebral multicontact electrodes
venue: Human brain mapping
year: 2017

abstract: The importance of the reduction of oxygen in water in fuel cell and metal/air batteries is well known. Platinum electrodes were the first choice for the use in fuel cells, but their high cost has necessiated the researches leading to preparation of low cost modified electrodes in which there is decreased oxygen reduction at lower potential. Hence the current interest lies in the utilization of carbon based modified electrodes and mediator. Over the last few years, the electrocatalysis of oxygen reduction on various conducting polymers/ceramic modified electrodes were studied. These materials are specially important owing to their bridging the world of conducting polymers and that of nanoparticles.
title: The conductivity of conjugated polymer and conducting polymer inorganic hybrid nanocomposites are discussed. Electrocatalysis of conducting polymer inorganic hybrid nanocomposites oxygen reduction in Direct Methanol Fuel cells (DMFCs) electrocatalysis of Pt based nanocomposites, alternative cathode
year: 2015