Three chemical cleaning procedures for InSb(111) wafers were studied. X-ray photoelectric spectroscopy, and scan electron microscope were used to assess their credibility for use in manufacturing the InSb detectors. It is shown, a suitable thermal treatment can remove In oxide and Sb oxide and therefore, all procedures approach to similar results from this point of view. But undulation and peel-like features has been observed on InSb(111) surface etched by all etchants except a modified CP4A etchant (HNO3:CH3COOH:HF:H2O at 2:1:1:10). Also control the etch rate and etching process can be done better in CP4A than the others. The XPS results show different spectra for SbOx and InOx when, InSb(111) is compared with InSb(100) and it means that, for different crystal orientation and different etchant there are different cleaning method for removing SbOx and InOx. Finally the effect of etchants on the performance of InSb detectors was shown.

The vacuum thermal evaporation technique (VTET) allows the deposition of highly homogeneous thin films with excellent step coverage. This method has already shows promising results for the deposition of indium sulphide at different substrate temperature between 453 and 513 K. Indium sulphide thin films have been synthesised and deposited by vacuum thermal evaporation technique. Experimental parameters have been adjusted in order to obtain a high band gap and low absorption material at low deposition temperature, as required for photovoltaic applications. The structural, morphological and optical properties were characterised by X-ray diffraction analysis, Surface Electron Microscopy and spectrophotometry. The VTET-In2S3 thin films are homogeneous and crystallised at 513 K with direct band gap values of about 2 eV.

The plasma parameters for the fast deposition of highly crystallized microcrystalline silicon (µc-Si) films with low defect density are presented using a high-density and low-temperature SiH4-H2 mixture microwave plasma. A very high deposition rate of $\sim $65 Å/s was achieved for a SiH4 concentration of 67% diluted in H2 with a high Raman crystallinity Ic/Ia > 2.5 and a low defect density of 1−2 × 1016 cm−3 by adjusting the plasma conditions. Contrary to the case of a conventional rf plasma, the defect density of the µc-Si films strongly depends on substrate temperature, Ts, and increases with increasing Ts even if Ts is below 300 °C. This indicates that the real temperature at the growing surface is higher than the monitored value. A sufficient supply of deposition precursors such as SiH3 at the growing surface under an appropriate ion bombardment is effective for the fast deposition of highly crystallized µc-Si films as well as for the suppression of the amorphous incubation and transition interface layers at the initial growth stage.

Solar blind detectors based on AlGaN heterostructures grown on sapphire by Molecular Beam Epitaxy and with a dielectric interference filter deposited on the back side are demonstrated to provide record spectral selectivity. Rejection ratios of 2 × 104, and better than 5 × 104, measured between 280 and 320 nm, are achieved in Metal Semiconductor Metal detectors and Schottky diodes respectively. The whole detector process is fully compatible with low cost array fabrication.

The breakdown electroluminescence spectra of individual microplasmas in a p-n-junction with microplasma breakdown, which was prepared on a 3C-SiC crystal, have been investigated. The clear periodic structure of an oscillatory nature, which was discovered first by the authors recently, with a period of about 0.16 eV was observed in the emission spectra of this microplasma. The oscillations were superimposed over the entire investigated spectral region between 1.8–4.7 eV. The amplitude of the oscillations amounted to 0.05–0.25 of the background radiation intensity. The characteristics of the oscillatory structure and of the background radiation have been separated and compared. It turned out that they depend in different ways on the temperature and on the sample-powering regime. It has been revealed that the oscillatory structure is associated apparently with the energy transition (X3c−X1c) in the conduction band.

Nanocomposite films containing Au nanoparticles embedded in a polymer matrix were prepared by vapour phase co-deposition of Au and polymers (Teflon AF and Poly($\alpha $-methylstyrene)) in high vacuum. The microstructure of the composite materials as well as metal content strongly depend on the condensation coefficient of the Au atoms, the deposition rates of the components, the substrate temperature, and the type of polymer matrix. The condensation coefficient, which varies between 0.03 and 1, was determined from energy dispersive X-ray spectrometer (EDX) and surface profilometry. It is shown that the microstructure of nanocomposites (size, size distribution, and interparticle separation of metal clusters), which was determined by transmission electron microscopy, can be controlled by the deposition parameters and the choice of polymer matrix. The optical absorption in the visible region due to the particle plasmon resonance has a strong dependence on the metal filling factor. The correlation between the microstructure of nanocomposites and optical properties, studied using UV-Vis spectroscopy, was also established. Further more, the electrical properties of the composites were studied as a function of the metal volume fraction. It was observed that the nanocomposite films exhibit a percolation threshold at a metal volume fraction of 0.43 and 0.20 for gold nanoclusters in Teflon AF and Poly(α-methylstyrene), respectively.

The aims of this article is presentation of a numerical simulation of the six degrees of freedom evolution of an inertial flywheel with high speed rigidly bound to a permanent magnet close a multifilamentaries superconductors winding. The simulation starts immediately after injecting an initial current in the winding and short circuiting it. We studied two configurations. One qualified as pendulum type in which the magnet is `suspended' to the winding and the other as a top type, the magnet `resting' on the winding. The simulation leads to a steady state conditions only for the pendulum type.

In this work, a non-Fourier heat conduction model considering the effect of heat source is presented and applied into pulsed laser deposition (PLD) technique to study target temperature evolvement when the target is radiated by high-power (≥1013 W/m2) short-pulse (in the order of picosecond) laser. Under this kind of irradiation conditions, the finite propagation speed of heat wave must be taken into account. The temperature profiles obtained from our model are compared with those obtained from Fourier conduction model and non-Fourier model without heat source term. The effects of heat source and relaxation time on non-Fourier temperature evolution are emphatically studied. It is found that the effect of non-Fourier heat conduction mainly shows in that it takes the target temperature certain time to start to increase and the increasing of temperature with time is faster obviously than that of Fourier heat conduction case. As for the heat source, it plays an important role that makes surface temperature ascending quicker than the case without heat source. Results also demonstrate that with the increasing of relaxation time, the Non-Fourier effect becomes remarkable more and more. Meanwhile, the corresponding physical mechanisms are investigated in detail.

In the present paper, we report the compensation effect for the crystallization of different binary and ternary systems of some chalcogenide glasses. We have observed Meyer-Neldel rule between the pre-exponential factor K0 of rate constant K(T) of crystallization and activation energy of crystallization Ec in the present case.

Tris(8-hydroxyquinoline) aluminium (Alq3) inserted in the structure ITO/Alq3/Al is used to show how dielectric spectroscopy and a $\log \varepsilon '' ={\rm f}(\log \omega)$ representation can separate dielectric conductivity by bound charges from $\gamma _{0 }$ conductivity due to residual pseudo free charges. Coupled with the I(V) characteristic, the $\log \varepsilon '' ={\rm f}(\log \omega)$ representation allow to study the mobility of these carriers as a function of the applied bias voltage V; then the mobility was estimated to be $\mu \approx 2 \times 10^{-6}$ cm2 V−1 s−1 (with V = 0), and we demonstrate that $\mu $ approximately follows a Poole-Frenkel like law. Consequently, these results show that mobility determined by field effects is generally overestimated by around one order of magnitude for an electric field at around 1  MV cm−1. More precisely, we demonstrate that pseudo free charges exhibit a field and weakly temperature dependent mobility, which is in contrast to carriers involved in the trap–charge limited current regime which exhibit a temperature dependent and field independent mobility.

We propose a pair of approaches to account for voltage driven coils when solving 3D eddy-current problems with a discrete geometric approach. The formulation we use is based on the circulation a of the magnetic vector potential on primal edges and on a scalar potential χ on conductor primal nodes. The proposed approaches consider distributed or localized voltage sources respectively and they can be applied to general coil geometries. The results are compared with those obtained with Finite Elements.

This work is a contribution to the understanding of mechanisms controlling the Atmospheric Pressure Glow Discharge (APGD). The approach consists in developing an electrical model of the discharge based on electrical circuit compounds. This model takes into account the main phenomena of the discharge including the memory effect and the creation of the cathode fall. It allows to have a general view of the process and can be easily associated to the power supply with short computational duration; it is also an interesting tool for the optimization of the whole process.

The structural and magnetic properties of Nd2AlFe16−xMnx (x = 1, 2, 3, 4, and 5) compounds have been investigated by means of X-ray diffraction and magnetization measurements. The Nd2AlFe16−xMnx compounds have a rhomhedral Th2Zn17-type structure. There exist an anisotropic strong spontaneous magnetostriction in magnetic state and a negative thermal expansion near their Curie temperatures. The nearly zero thermal expansion coefficient is found over a broad temperature range including room temperature from 103 to 342 K for Nd2AlFe15Mn compound. In the magnetic state, the thermal expansion coefficients of Nd2AlFe16−xMnx compounds increase with the increasing Mn concentrations x. Mn concentration dependences of the lattice parameters and unit-cell volume, the spontaneous magnetostrictive deformation, the Curie temperature, and the saturation magnetization have been discussed.

The first purpose of this work is to design a new observation technique for the Direct Torque Control (DTC). We put emphasis on robustness especially at very low speed, which represents the basic problem of the DTC operating, and on the optimization of the time computing. The reduced order observer is defined by decoupling the full order one in $\alpha $ and $\beta $ axis. The second basic aim of this paper is to apply the DTC strategy to multi-machine multi-inverter industrial systems. Speed and tension controls are designed; their performances and parameter robustness are analyzed and compared with those obtained with a Flux Oriented Control (FOC). Mechanical and electrical couplings constitute the principal operation difficulty of these systems mainly when one of the machines is perturbed.

The principle of a specific optical device which was designed to homogenize the power density distribution of a CO2 laser beam is described in the paper. The detailed formulas to express the relation between power density distribution of converted beam and optical parameters of device are given. Based on this relation, a scheme to optimize the device is presented. The power density distributions simulated by computer before and after optimization are given. A tentative criterion to estimate the uniformity of a beam spot in which there are interference fringes, is put forward.

The purpose of this paper is to describe the development and the use of two measurement techniques especially adapted to the rapid determination of the thermophysical properties of evolutive porous media. The first technique exploits the method of the “heated and non-heated wires” and is validated on wet clay by comparison with previous works [Mounanga et al., Eur. Phys. J. Appl. Phys. 26, 65 (2004)]. It is then used to quantify the evolution of both thermal conductivity and volumetric heat capacity of hardening cement pastes maintained at 294 ± 1 K. The second technique is based on the classical method of the “heating film” and a data treatment using forward calculation. This technique is first used to measure the properties of well-known materials (hardened mortars, wet sand [Mounanga et al., Eur. Phys. J. Appl. Phys. 26, 65 (2004); Delacre, Ph.D. thesis, University of Artois, 2000] and glass [Bastian, Rev. Phys. Appl. 22, 431 (1987)] and then applied to media whose properties evolve both over time and through space (drying sand).

There has been a renewed interest in zinc oxide in the materials science community after it was shown to be ferromagnetic when doped with cobalt. However, it has remained difficult to tell whether the origin of the phenomenon was intrinsic or due to secondary phases. Here, we examine with analytical transmission electron microscopy the distribution of cobalt in a thin film of ferromagnetic Al-doped Zn0.7Co0.3O that we have grown by pulsed laser deposition on alumina. We show that precipitation of a secondary phase does occur, but that it concerns less than 10% of the cobalt atoms. The precipitates appear to be made of hexagonal metallic Co, and their average diameter is 4 nm. Their magnetism could be the reason for the low measured Curie temperature of the sample (50 K). On the other hand, the overall measured magnetization of 0.7 $\mu_B$ per cobalt atom suggests that the Co atoms in solution are at the origin of most of the signal.

A series of M-type hexaferrite samples with composition Sr1−xLaxFe12O19 (x = 0.00, 0.05, 0.15 and 0.25) were prepared by standard ceramic technique. AC electrical conductivity measurements were carried out at different frequencies (20 Hz–1 MHz) and at different temperatures. The dielectric constant and dielectric loss tangent were measured in the same range of frequencies. The experimental results indicate that AC electrical conductivity increases on increasing the frequency as well as the temperature, indicating magnetic semiconductor behavior of the samples. The increase in AC electrical conductivity with frequency and temperature has been explained on the basis of Koops Model whereas dielectric constant and dielectric loss tangent has been explained with the Maxwell–Wagner type interfacial polarization in agreement with the Koops phenomenological theory.

In this paper we model the thermoelectric magnetic field around isotropic inclusions in anisotropic media. It is demonstrated that while the presence of the inclusion will be the dominant source of the thermoelectric signal, the anisotropy of the host material will affect the signal. Although such a phenomenon will occur for all shapes of inclusions, for simplicity we shall demonstrate our theoretical and numerical modeling on the more mathematically tractable case of a cylindrical inclusion aligned along an axis of symmetry of an anisotropic metal medium.

We report on the characterization of the behaviour of an anisotropic magnetoresistive sensor undergoing a 100 kHz flipping of the magnetic domains, i.e. at frequencies two/three orders of magnitude higher than conventionally recommended. The noise analysis allows for the optimal setting of the relevant parameters defining such high-frequency, and hitherto unexplored, operation regime. Precision and accuracy performance in static conditions have been assessed by keeping into account the role of the sensor temperature. This last parameter has been evaluated by suitably manipulating the signals occurring at the sensor itself. The used technique can provide the base for a temperature sensor conditioning to be employed in magnetometers using this kind of devices.