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Peer Reviewed
See detailELECTRICAL AND THERMOMAGNETIC EFFECTS IN BI1.7PB0.3SR2CA2CU3O10 SUPERCONDUCTING CERAMICS
Pekala, M.; Bougrine, Hassan ULg; Ausloos, Marcel ULg

in Journal of Physics : Condensed Matter (1995), 7(28), 5607-5621

We report the electrical resistivity and thermoelectric power of polycrystalline Pb-doped Pi 2:2:2:3 superconductors. In particular the mixed-state properties are investigated by measuring the ... [more ▼]

We report the electrical resistivity and thermoelectric power of polycrystalline Pb-doped Pi 2:2:2:3 superconductors. In particular the mixed-state properties are investigated by measuring the longitudinal and transverse (Nernst) thermoelectric power. For the first time we show the presence of hysteresis in a high magnetic field for the Nernst effect. We discuss the variation with magnetic field in the properties with respect to the zero-field case and show the power-law behaviour with exponents depending on the transport quantity. We extract 'derived properties' such as the effective mass, the transport entropy, the Ginzburg-Landau parameter, the thermal Hall angle and the activation energy and compare them with previous data on related systems. [less ▲]

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See detailElectrical characterization of InGaN/GaN multiple-quantum-well structures by thermal admittance spectroscopy
Nguyen, Ngoc Duy ULg; Schmeits, Marcel; Germain, Marianne et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2002)

Experimental results of electrical characterization of InGaN/GaN multiple-quantum-well electrolu- minescence test structures obtained by thermal admittance spectroscopy are presented. The stu- died GaN ... [more ▼]

Experimental results of electrical characterization of InGaN/GaN multiple-quantum-well electrolu- minescence test structures obtained by thermal admittance spectroscopy are presented. The stu- died GaN : Mg/5 × (InGaN/GaN)/GaN:Si structures were grown on c-plane sapphire substrate by metal-organic vapor phase epitaxy. Admittance measurements were conducted from room tem- perature down to 125 K for a wide frequency range and for different applied bias voltages. Analy- sis of the capacitance versus frequency curves shows the presence of several cutoff frequencies which originate from the response of equivalent RC series circuits and give peaks in the conduc- tance divided by angular frequency. The dependence of the position and the amplitude of these peaks on temperature is discussed. [less ▲]

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Peer Reviewed
See detailElectrical characterization of InGaN/GaN multiple-quantum-well structures by thermal admittance spectroscopy
Nguyen, Ngoc Duy ULg; Schmeits, Marcel; Germain, Marianne et al

Poster (2002)

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See detailElectrical characterization of pGeSn/nGe diodes
Baert, Bruno ULg; Gupta, Somya; Gencarelli, Federica et al

Conference (2014, June 03)

I-V characteristics of pGeSn/nGe diodes have been measured and show very good properties. Simulations of the same structure are able to reproduce most of the observed behavior and point to the ... [more ▼]

I-V characteristics of pGeSn/nGe diodes have been measured and show very good properties. Simulations of the same structure are able to reproduce most of the observed behavior and point to the predominating influence of parameters such as the band gap energy of the GeSn layer. C-V characteristics showing little frequency dependence have also been measured, and their analysis for the determination of the carrier concentration is confirmed by simulations. More investigations, including the effect of temperature and other defects at the interface or in the bulk of either layers are still required in order to explain some of the observed behaviors, notably the reverse saturation current. [less ▲]

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See detailElectrical characterization of semiconductor heterostructures by admittance spectroscopy
Nguyen, Ngoc Duy ULg

Scientific conference (2010, December 16)

Electrical characterization by admittance spectroscopy enables the study of interface properties of semiconductor structures such as p-n junctions, Schottky diodes, light-emitting systems, photodiodes ... [more ▼]

Electrical characterization by admittance spectroscopy enables the study of interface properties of semiconductor structures such as p-n junctions, Schottky diodes, light-emitting systems, photodiodes, solar cells or quantum well devices. The technique consists in monitoring the complex admittance of the device under test as a function of frequency, applied dc voltage and temperature. This method gives a direct access to the emission-capture processes occurring between an impurity level and the conduction or the valence band and leads to the determination of important electronic properties including the activation energy and the carrier capture cross sections. In the case of organic semiconductors, the field-dependent carrier mobility can be measured as well. However, the interpretation of the admittance curves is straightforward only under restrictive assumptions such as full ionization of the shallow dopant, with a concentration larger than the deep impurity concentration. Numerical simulations, based on the solution of the basic semiconductor equations, allow to carry out a detailed analysis of the steady-state and small-signal electrical characteristics of the systems and thus contribute to a better understanding of the conduction mechanisms and of the microscopic origin of the features in the experimental admittance spectra. In this presentation, the results obtained for different structures are shown in order to illustrate the method. [less ▲]

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See detailElectrical conduction by interface states in semiconductor heterojunctions
El Yacoubi, Mohamed; Evrard, Roger ULg; Nguyen, Ngoc Duy ULg et al

in Semiconductor Science & Technology (2000), 15

Electrical conduction in semiconductor heterojunctions containing defect states in the interface region is studied. As the classical drift-diffusion mechanism cannot in any case explain electrical ... [more ▼]

Electrical conduction in semiconductor heterojunctions containing defect states in the interface region is studied. As the classical drift-diffusion mechanism cannot in any case explain electrical conduction in semiconductor heterojunctions, tunnelling involving interface states is often considered as a possible conduction path. A theoretical treatment is made where defect states in the interface region with a continuous energy distribution are included. Electrical conduction through this defect band then allows the transit of electrons from the conduction band of one semiconductor to the valence band of the second component. The analysis is initiated by electrical measurements on n-CdS/p-CdTe heterojunctions obtained by chemical vapour deposition of CdS on (111) oriented CdTe single crystals, for which current--voltage and capacitance--frequency results are shown. The theoretical analysis is based on the numerical resolution of Poisson's equation and the continuity equations of electrons, holes and defect states, where a current component corresponding to the defect band conduction is explicitly included. Comparison with the experimental curves shows that this formalism yields an efficient tool to model the conduction process through the interface region. It also allows us to determine critical values of the physical parameters when a particular step in the conduction mechanism becomes dominant. [less ▲]

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See detailElectrical conductivity in carbon black-loaded polystyrene-polyisoprene blends. Selective localization of carbon black at the interface
Soares, Bluma G; Gubbels, Frédéric; Jérôme, Robert ULg et al

in Polymer Bulletin (1995), 35(1-2), 223-228

The electrical conductivity of carbon-black loaded polystyrene-polyisoprene blends has been studied. In this ternary system, the filler is at the interface of co-continuous polyblends as confirmed by the ... [more ▼]

The electrical conductivity of carbon-black loaded polystyrene-polyisoprene blends has been studied. In this ternary system, the filler is at the interface of co-continuous polyblends as confirmed by the very low value of the filler percolation threshold (0.2 vol % for blends compression molded at 250 degrees C) and by optical microscopy. As a result of the selective localization of carbon black at the interface, the percolation threshold is very sensitive to the compression molding temperature. [less ▲]

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Peer Reviewed
See detailElectrical investigation of TCMs: role of structural defects and external stress
Langley, Daniel ULg; Giusti, Gael; Consonni, Vincent et al

Conference (2012, October 24)

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See detailElectrical investigations of granular arches
Dorbolo, Stéphane ULg; Vandewalle, Nicolas ULg

in Physica A: Statistical Mechanics and its Applications (2002), 311(3-4), 307-312

Compaction dynamics and granular arches have been studied using the electrical resistance of a packing. An exponential decay of the resistance is found whatever the electrical current is. A fluctuation ... [more ▼]

Compaction dynamics and granular arches have been studied using the electrical resistance of a packing. An exponential decay of the resistance is found whatever the electrical current is. A fluctuation regime is then encountered. A characteristic relaxation time has been pointed out and is linked to the arch formation in the system. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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Peer Reviewed
See detailElectrical mapping of spontaneous ventricular fibrillation in acutely ischemic pigs.
Desaive, Thomas ULg; Janssen, Nathalie; Péters, Fabrise et al

in Proceedings of the 5th Belgian Day on Biomedical Engineering, 2005, Brussels (2005)

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See detailElectrical microenvironment influence on the hydrolytic activity of free and immobilised Yarrowia lipolytica lipase
Paquot, Michel ULg; Deleu, Magali ULg; Beaufils, C. et al

in Biotechnology Letters (1996), 18(1), 73-78

The role of electrical properties of interfaces upon the activity of free and immobilised Yarrowia lipolytica lipase has been investigated. Sodium taurocholate and Sedipur 400, an anionic polyacrylamide ... [more ▼]

The role of electrical properties of interfaces upon the activity of free and immobilised Yarrowia lipolytica lipase has been investigated. Sodium taurocholate and Sedipur 400, an anionic polyacrylamide, enhance the negative character of the fatty droplets of substrate and tend to improve the lipolytic activity while the cationic polyacrylamide (Sedipur 900) has opposite effects. Ca+ which reduces the fatty droplets charge as Sedipur 900, is however a good activator of the enzyme. The role of electrical properties on the optimum pH of the immobilised enzyme is clearer. Immobilisation of the lipase on a positively charged support shifts its optimum pH to acidic pH by repulsion towards H+ ions around the support. [less ▲]

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See detailElectrical modelling of interface traps in GeSn MOS structures
Baert, Bruno ULg; Cerica, Delphine; Schmeits, Marcel ULg et al

Conference (2014, November 13)

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See detailElectrical properties of improper ferroelectrics from first principles
Stengel, Massimiliano; Fennie, Craig J.; Ghosez, Philippe ULg

in Physical Review. B, Condensed Matter and Materials Physics (2012), 86

We study the interplay of structural and polar distortions in hexagonalYMnO3 and short-period PbTiO3/SrTiO3 (PTO/STO) superlattices by means of first-principles calculations at constrained electric ... [more ▼]

We study the interplay of structural and polar distortions in hexagonalYMnO3 and short-period PbTiO3/SrTiO3 (PTO/STO) superlattices by means of first-principles calculations at constrained electric displacement field D. We find that in YMnO3 the tilts of the oxygen polyhedra produce a robustly polar ground state, which persists at any choice of the electrical boundary conditions. Conversely, in PTO/STO the antiferrodistortive instabilities alone do not break inversion symmetry, and open-circuit boundary conditions restore a nonpolar state.We suggest that this qualitative difference naturally provides a route to rationalizing the concept of “improper ferroelectricity” from the point of view of first-principles theory. We discuss the implications of our arguments for the design of novel multiferroic materials with enhanced functionalities and for the symmetry analysis of the phase transitions. [less ▲]

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See detailElectrical resistance tomography sensor simulations: comparison with experiments
Fransolet, E.; Crine, Michel ULg; L'Homme, Guy ULg et al

in Measurement Science & Technology (2002), 13(8), 1239-1247

This paper compares experimental results (differences of potential), obtained with a 16-electrode electrical resistance tomography (ERT) device using the adjacent-electrode pair measurement strategy, with ... [more ▼]

This paper compares experimental results (differences of potential), obtained with a 16-electrode electrical resistance tomography (ERT) device using the adjacent-electrode pair measurement strategy, with finite-element method (FEM) simulations in two and three dimensions. In the first part of the paper, ERT measurements made on a homogeneous medium are compared with two- and three-dimensional FEM simulations. It is shown that the dependence of the electrical field on the axial coordinate cannot be neglected. Consequently, only the three-dimensional FEM simulations are able to fit the experimental results. In the second part of the paper, ERT measurements on static physical phantoms immersed in water evidence that ERT is significantly more sensitive to non-symmetrical distributions than to symmetrical ones. This observation is confirmed by three-dimensional FEM simulations performed on numerical phantoms that mimic the physical ones. In the last part of the paper, an attempt to use three-dimensional simulations to determine the characteristics (diameter and gas content) of a gas core created by injecting a gas flow from a single-orifice gas sparger leads to promising results. [less ▲]

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See detailElectrical resistivity and magnetic susceptibility measurements on Np2T2X compounds
Pereira, Laura C.J.; Seret, Alain ULg; Wastin, Frank et al

Poster (1995, April)

Detailed reference viewed: 25 (0 ULg)
Peer Reviewed
See detailElectrical resistivity and magnetic susceptibility of AnT2Al3 (An = Np, Pu; T = Ni, Pd)
Seret, Alain ULg; Wastin, Franck; Warenborgh, Joan-Carlos et al

Poster (1994, August)

Detailed reference viewed: 4 (0 ULg)