Electronic properties of ITGO (Sn+Ge doped In2O3) thin films have been investigated for various compositions with decreasing doping levels (molar ratios [Sn]/[In] ≤ 0.05 with [Ge] = 0.2 [Sn]). Conductivity and Hall measurements versus temperatures ranging from 77 to 500 K have shown that two electron scattering mechanisms are to be considered. Even though ionised impurities dominate the electron scattering in the whole temperature range, the influence of optical phonons cannot be neglected. It appears gradually from 200 to 250 K and involves a marked decrease of the electron mobility with temperature. The influence of the doping level on the electron mobility has also been studied. It can be correlated with the effective mass variations deduced from the evolution of the thermoelectric power versus temperature [1, 2] and with the observation by optical absorption of localised states for the lowest doping levels [1, 8].

Non destructive techniques like scanning infrared microscopy and light beam induced current mapping are used to reveal the presence of stacking faults in heat treated Czochralski grown silicon wafers. In oxidized or contaminated samples, scanning infrared microscopy reveals that stacking faults grow around oxygen precipitates. This could be due to an aggregation of silicon self-interstitials emitted by the growing precipitates in the (111) plane. Light beam induced current maps show that the dislocations which surround the stacking faults are the main source of recombination centers, especially when they are decorated by a fast diffuser like copper.

This paper proposes a new process of temperature measurement of a material or object at microwave frequencies. This process allows self-balancing of the temperature measurement system and takes into account any mismatching between the antenna and the radiating object. The process uses a temperature sensor based on a monolithic integrated circuit. A theoretical and experimental study is conducted to test this process.

Dielectric measurement characteristics such as the dissipation factor, relative permittivity and conductivity as a function of temperature and frequency have been achieved on composite materials based on different epoxy resins filled with alumina inclusions. The analysis of the results show the presence of porosity and inhomogeneity in these materials. The study of the dissipation factor, as a function of temperature at high frequencies, has shown an unexpected absorption phenomenon in materials designed to be utilized as electrical insulators. The identification of the entities responsible for this relaxation shows that the entities result from one of the components of the material. These results can also confirm the inhomogeneity of the materials.

Dielectric measurements of a new antiferroelectric liquid crystal series exhibiting different phase sequences have been carried out as a function of frequency from 10 Hz to 10 MHz. Structural properties of SCα* and ferrielectric SCFI* phases were discussed on the basis of the experimental results of temperature and dc bias field dependencies of the dielectric modes. Besides the soft mode observed around the SA−SCα* phase transition, a Goldstone mode was detected in the SCα* phase indicating a helicoidal structure with small pitch values. In agreement with a bilayer ordering model, the dielectric absorption in the SCFI* phase was splitted up into two contributions: one related to a Goldstone mode and the other to an azimuthal antiphase mode.

We α present and demonstrate a method to determine the refractive index and absorption changes in a two mode fiber interferometer. Measurement on the 632 nm transitions in Er3+ silica fiber shows that refractive index and absorption changes result from ground and excited state transitions respectively. The GSA/ESA cross-sections ratio was found to be 14.

Based on the deformation theory of plasticity the problem of pressure distribution in a compressed layer at phase transition experiencing a plane plastic deformation is considered. It is found that in the pressure distribution near the phase boundaries anomalies emerge in the form of a “step” or a local maximum caused by volume jumps at phase transition. It is shown that these anomalies and differences in yield limits of the phases can lead to essential change of pressure in the center of the layer in comparison with its value in absence of phase transition, but under equal external load. The maximal value of external load admitting the considered solution is found. The kinetics of possible isothermal regimes of phase transition leading to change in the time-pressure distribution in the plastic layer is investigated.

We have accelerated the ageing of CuAlS2 by the application of a static electrical field for different degradation times. We have investigated the admittance spectroscopy and the scanning electron microscopy to follow and understand the (mass-charge) coupled transport processes produced in the volume and on the surface of these films. The electrical constraint induces, after an incubation phase, an activated decrease of the resistance, followed by a susbstantial increase correlated to the formation of an open circuit. This degradation occurs more rapidly for the films having initially a lower resistance, due to the thermal dissipation which increases considerably the temperature to about 140 °C. Admittance spectra reveal, at low frequencies, a capacitive loop related to the formation of a charge space induced by copper diffusion. Such migration develop induces the formation of copper arborescences, spreading from the cathode towards the anode. The effect of these structures on the properties of the degraded films is discussed in relation to electromigration and associated processes (whiskers, fracture, healing, bridge-building, ...). Also, we have noticed their similarity with fractal phenomena such as electrodeposition and dielectric breakdown.

Une méthode d'obtention de couches minces photoconductrices de MoSe2  a été mise au point. Ces couches sont obtenues à partir d'une structure multicouches Mo/Se/Mo/Se...Mo/Se déposée sur une fine couche de Ni. À l'issue d'un traitement thermique on a montré que des couches minces stœchiométriques, texturées et photoconductrices sont obtenues.

A new control method of cascaded power supply converters using the sliding approach is presented here. Variable Structure Control enables the problems of stability brought about by cascaded converters to be solved and its robust behaviour acts against variations in the load parameters and supply voltage.

Les supraconducteurs à haute température critique ouvrent des perspectives prometteuses dans le domaine de l'électronique en raison de la maîtrise de la croissance de films minces de haute qualité cristalline et physique, malgré des difficultés spécifiques. Des dispositifs, aussi bien actifs que passifs, commencent à être réalisés dans divers laboratoires, montrant que des applications peuvent être effectivement envisagées à relativement court terme.

Planar metal/semiconductor/metal (PMSM) junctions buried in a SiO2 layer are fabricated using electron beam lithography on a silicon sample. A technique of jump of pixels is used to obtain different sizes of junctions, the smallest having an inter-electrode distance of 5 nm. The current-voltage characteristics and the variation of the junction conductance with the temperature down to 8 K have been studied. At all sizes and for both polarities, the I−V curves correspond to the reverse characteristic of a metal/semiconductor contact. At low bias voltage, the influence of a thin insulator interfacial layer between the metal and the semiconductor has been pointed out. For these junctions, a non-linear low voltage I−V characteristics is observed before the large voltage thermionic emission regime. For the smallest junctions obtained without interfacial oxide layer, a linear I−V characteristic is recovered at low voltage. Their conductance can be lowered by decreasing the temperature.

Crystalline Ni3B samples have been irradiated with GeV heavy ions (from 16O to 238U) at low temperature in order to study the damage induced in this compound by ion electronic energy loss. Electrical resistance measurements were performed in situ during irradiation and during annealing. Subsequent X-ray diffraction data and transmission electron microscopy observations reveal a change of the radiation damage process as a function of the electronic stopping power (dE/dx)e. At low (dE/dx)e isolated defects are created, while at high (dE/dx)e irradiation generates continuous amorphous tracks. Amorphous inclusions (discontinuous tracks) are most likely formed in the intermediate (dE/dx)e range. The amorphous phase induced by swift heavy ion irradiation, different from that formed by quenching techniques, is unstable at room temperature over a period of a few months.

Microscale phenomena between the surface of chemically vapour deposited silicon films and a silicon nitride tip was investigated using Scanning Force Microscopy. An analysis of friction forces for different scan directions is presented. For different applied forces, the friction forces were measured and consequently the friction coefficient was calculated. We found that the average friction force linearly increases with the applied force and is reversible when unloading. Connection between the surface roughness and the friction coefficient was experimentally demonstrated.

The authors propose study methods of three phase short circuits of an induction traction motor. Methods are based on finite element model or equivalent circuits of the machine and take into account, more or less accurately, saturation and deep bar effects. Depending on the modeling level, they can be used to study short circuit torque or current maxima, waveforms or local constraints. The proposed methods are applied to a 1.5 MW - 4 pole traction motor short circuit study.

The operation of Pichugin pulse generators (named after their Russian inventor) is studied. A set of equations for a one-stage generator enables us to point up the important frequency properties of the magnetic core transformer. An analytical and numerical study of a three-stage generator is performed. Improvements, concerning the voltage gain, are suggested; the consequences on the rise time value are analysed. A new conception method, based on compensated and asymmetrical stages, is proposed. It is a compromise solution to decrease the rise time value and to increase the voltage gain. By using this structure, the realization of a 120 kV, 145 ns rise time three-stage pulser is proposed; its operating at a frequency greater than 1 kHz is studied.

A 120 kV / 200 ns / 13 J transmission line generator building is accurately studied. A design method for achieving compact and reliable Blumlein generators is elaborated and validated by three realizations. In order to estimate the transmission line transformer amplification and droop, a set of equations is established and a new simplified gain expression is suggested. Another set of equations to characterize the secondary parasitic lines is settled. By turning it to account, an innovating building method using iron powder to reduce the transmission line transformer parasitic effects, is proposed. In this case, the transmission line generator energy yield reaches 93%.

We have studied the effect of the substrate on the structural and electrical properties of Ni thin films. Series of Ni thin films have been prepared by dc diode sputtering on four different substrates, glass, Si(111), Si(100) and mica; the Ni thickness ranges from about 47 nm to 317 nm. We observed that Ni grown on glass has no texture. On the other hand Ni deposited on Si gets the 〈111〉 preferred orientation for all samples, even the thinner ones. Grain sizes were found to increase with increasing thickness for Ni/glass and Ni/Si(100), with the grains in Ni/Si(100) much larger than the corresponding ones for Ni on glass. The lattice constant of Ni on glass is smaller than that of the bulk. For the Ni on Si, however, the lattice constant is practically equal to the bulk value. We noted that the resistivity ρ decreases with increasing thickness and with increasing grain size for practically all samples. Also the Ni thin films deposited on a semiconductor substrate (Si(100) and Si(111)) get a higher resistivity than Ni on an insulator (Ni/glass for example) for the same Ni thickness. No magnetoresistance was observed in these Ni thin films at ambient temperature and for about a half kOe perpendicular magnetic field. These experimental results will be interpreted and discussed.

This paper describes a method for modelling the printed conductors employed in high-frequency (range 10 kHz-1 MHz), medium-power (several kW) static converters, in order to simulate their conducted interference emissions. The principle of this method is to divide the circuit's layout into elementary rectangles. These rectangles are then substituted by a bundle of thin cylindrical wires. Afterwards, it becomes possible to determine an electrical equivalent circuit for each bundle, which integrates inductive, capacitive and resistive effects. In the first section of this paper, the theoretical development, with respect to a single rectangular conductor, is presented. The printed conductor and the thin-wire bundle equivalence conditions are then specified in the second section, and the validity of this principle is experimentally verified. The third section is devoted to modelling the coupling phenomena between two printed conductors. Special attention has been paid to separating strong and negligible couplings, in order both to reduce the computing time and to extract equivalent circuits for a complex layout. Quantitative coupling criteria, based on geometrical and current quantities, are proposed; they establish the complexity of the equivalent circuits and thereby the simulation time. The paper's final section focuses on the experimental aspects of this research work. A chopper has been developed on a PCB. Experimental and theoretical results are also compared: the impedance curves of the entire circuit and the conducted emission spectrum of the converter are presented and discussed. The role played by the PCB in the conducted EMI is clearly revealed and allows the designer to optimise the printed circuit pattern.

Low-frequency noise measurements were performed on intrinsic low pressure chemical vapor deposited polycrystalline silicon resistors. The current noise exhibits a transition from 1/f to 1/f0.6 behavior with the resistors biased in the linear region. The origin of the noise is related to carrier density fluctuation between conduction band and gap states consisting of deep states lying close to midgap with uniform energy distribution and exponential band tails. From analysis of the experimental data, the quality of the material is characterized with respect to the deposition pressure. When the resistors are biased in the non-linear regime, an additional noise is observed which is attributed to the temperature rise due to Joule-induced heating within the samples.