Thin films of antimony-doped tin oxide (ATO) have been prepared by the sol-gel dip-coating (SGDC) process, using tin(II) chloride dehydrate (SnCl2, 2H2O) and antimony (III) chloride (SbCl3) as host and dopant precursors respectively. The effect of antimony doping on the structural, thermal, electrical and optical properties of the samples were investigated. The structure of the (ATO) powders was analysed by X-ray diffraction (XRD) and the microstructure of the thin films by scanning electron microscopy (SEM). It was clear from these investigations that its structure is tetragonal rutile type and that an increase in Sb-doping decreases the crystallite size of the (ATO) particles. Thermal analysis by differential scanning calorimetry (DSC) showed that the crystallization temperature is about 370 °C whatever the Sb-doping amount. The lowest resistivity (2.6 × 10−3 ${\rm \Omega}$ cm) was obtained for the 5% Sb-doped film and the value of the band gap (3.69 eV) for the undoped film, increases slightly with Sb-doping increasing for the doped films.

Electrical properties ofSnO2-Co3O4-Nb2O5-Cr2O3 ceramicssintered at 1100−1400 °C were studied. Materials exhibitknown varistor properties (superlinear and symmetric current-voltagecharacteristic) only if sintered at relatively high temperatures of1300−1400 °C. In ceramics sintered at 1100−1200 °C,the current limiting effect (current is saturated and even decreasedwith voltage increase) and its transformation into the varistoreffect were found. It was ascertained that the capacitance ofsamples is decreased with increasing frequency more sharply forceramics sintered at 1100−1200 °C than at1300−1400 °C. The low-frequency capacitance and acconductance of ceramics sintered at 1100−1200 °C wereincreased and showed further strong decrease with electric field.The results of electrical measurements are discussed in terms of thebarrier model.

For industrial applications, microwave heating is an important technique. However, the homogenizationproblem must be taken into account to obtain rapid and reliable processes. Some industrialmicrowave heating systems are complex and expensive. In this paper, we propose a simple techniquewhich use a cavity excited by a linear or a circular electric field polarization. A better microwaveheating homogenization is obtain on ferrite and ethanol samples when the circular polarizationis used. A specific test bench was made to perform temperature measurements on several samplepoints.

Silicon carbide junction field effect transistor (SiC-JFETs) is a mature power switch newly applied in several industrial applications. SiC-JFETs are often simulated by Spice model in order to predict their electrical behaviour. Although such a model provides sufficient accuracy for some applications, this paper shows that it presents serious shortcomings in terms of the neglect of the body diode model, among many others in circuit model topology. Simulation correction is then mandatory and a new model should be proposed. Moreover, this paper gives an enhanced model based on experimental dc and ac data. New devices are added to the conventional circuit model giving accurate static and dynamic behaviour, an effect not accounted in the Spice model. The improved model is implemented into VHDL-AMS language and steady-state dynamic and transient responses are simulated for many SiC-VJFETs samples. Very simple and reliable optimization algorithm based on the optimization of a cost function is proposed to extract the JFET model parameters. The obtained parameters are verified by comparing errors between simulations results and experimental data.

Thin film organic field-effect transistors were grown with vapor-deposited polycrystalline-octithiophene on silicon oxide insulating layers. This component requires an ohmic source and drain contacts for ideal operation. The performance of organic electronic-devices is often limited by injection. In many real situations, however and specifically in organic devices, the injection of charge carriers from metals into semiconductors is non-linear. This has an adverse impact on the performance of thin film transistors, and makes the analysis of electrical measurements a complex task because contact effects need to be disentangled from transistor properties. This paper deals with the effects of non-ohmic contacts on the modeling of organic transistors and gives specific rules on how to extract the real transistor parameters using only electrical measurements. Several methods are used in order to study the influence of the contact resistance on the performance of organic transistors. This influence appears especially on the current-voltage characteristics of organic field effect transistor. We present a first method used to extract the key parameters of OFET such as; mobility, threshold voltage and contact resistances using the fit of the transfer characteristic of the devices. The second method has been used to exploit the different functional dependences of current on gate voltage which is induced by the presence of contact resistances in the linear and in the saturation regimes. All electrical key parameters of OFETs based on octithiophene have been extracted and we demonstrate that both mobility and contact resistance depend on gate voltage and temperature.

We present the successful recrystallization of Bechgaard salts with the microwire shape using the drop casting method. The samples are deposited on a substrate with previously prepared patterns made by optical lithography. The physical properties of the microwires are shown. The excellent transport properties show that this technique provides a new method for the tuning of the physical properties of molecular conductors and the first step toward applications. The pressure effects of the substrate on the conduction are discussed.

The electrical and photovoltaic characteristics of thermally evaporated thin films of 4-tricyano-vinyl-N,N-diethylaniline sandwiched between indium tin oxide and aluminium has been investigated. Dark current density-voltage characteristics under forward bias are found to be due to thermionic emission conduction at lower voltage region. While, at higher voltage region there is space-charge-limited conduction controlled by exponential trap distribution above the valance edge. Reverse bias curve is interpreted in terms of Poole-Frenkel effect. The device exhibits photovoltaic characteristics when it illuminated through Al electrode. The typical photovoltaic parameters were estimated at room temperature and under light illumination with an input power density of 80 mW/cm−2.

Glow discharges of oxygen and nitrogen were applied to low density polyethylene thin films in order to study accelerated oxidation and nitridation in the polymer. The studies were focused on the morphologic, crystalline and hydrophilic evolution promoted by plasma exposure. The particular chemical characteristics of the gases and the constant impact of high-energy particles on the surfaces produced different types of erosion. Oxygen plasmas produced the release of fragments from the polymeric surface which created fibered textures and nitrogen plasmas resulted in folded morphologies of nano and micro dimensions on polyethylene. The plasmas of both gases increased and decreased the crystallinity in the polymers, between 33% and 57%, with similar tendencies, differing only in the percentage of crystallinity. The plasma exposure produced a decrease in the contact angles of water on polyethylene in the first 30 min of plasma, from 70% in the untreated polymers, to 45% and 35% as a consequence of the polar groups added to the surface.

Regular patch arrays of random gold nanostructures were fabricated by electrochemical deposition of nanowires in ion track-etched templates. During ion irradiation with GeV ions of fluence 106, 107, or 108 cm−2, a shadow mask was used resulting in templates structured with square arrays of 50 μm holes and 100 or 150 μm pitch. The Au nanowires grown in the track-etched pores had a length of 7–28 μm and a diameter of ~300 nm, and were either solitary or clustered after template dissolution. The structured wire ensembles were systematically investigated with scanning electron and field emission scanning microscopy. Field emission with about 90% efficiency was achieved for wide-spaced patch arrays with medium and high number of Au nanowires at 1500 V for 20 μm anode distance. The current carrying capability of the patches strongly varied between 40 nA and 90 μA. The corresponding processing effects are correlated to adsorbates and nanostructural changes of the wires which give suitable hints for the optimization of structured Au nanowire cathodes.

Electrical and magnetic properties were studied for evaporated Fe thin films on glass and Si substrates. These properties were investigated by means of the four point probe and the magneto-optical Kerr effect techniques. Rutherford backscattering (RBS) and scanning electron microscopy (SEM) experiments show no interdiffusion at the interface Fe/Si for these samples. The electrical resistivity $\rho $ is found to be larger in Fe/glass than in Fe/Si for the same thickness. Diffusion at the grain boundaries seems to be the dominant factor in the $\rho $ values in this 6 to 110 nm thickness range; the reflection coefficient is smaller in Fe/glass (R ≈ 0.40) than in Fe/Si(100) (R ≈ 0.65). Saturation field and strain values confirm that Fe films have a stress induced magnetic anisotropy. Coercive field H C values range from 2.45 Oe for Fe/Si(100) to 17.65 Oe for Fe/Si(111) for the same Fe thickness (45 nm).

Fe-Cu alloys were grown on polycrystalline titanium substrates after determining the suitable deposition potentials. Based on the results obtained from cyclic voltammetry curves, a potential region between –1.8 V and –2.3 V vs. saturated calomel electrode (SCE) was selected. During growth, the electrochemical characterizations of the films were made by recording the current-time transients. The structure of films becomes more brittle with the increase of the deposition potential over –2.3 V vs. SCE due to extreme hydrogen liberation from cathode surface. The structural analysis by the X-ray diffraction demonstrated that the films have a typical body centered cubic of $\alpha $ -Fe preferentially grown in the (211) direction. The grain sizes, lattice parameters and interplanar spacings were also calculated. Energy dispersive X-ray spectroscopy measurements demonstrated that the ratio of Fe:Cu was almost the same. The magnetic analysis by vibrating sample magnetometer indicated that the coercivity of the films was slightly affected by the deposition potential.

The configurations, electronic structures and magneticproperties for M n N clusters (M = Fe, Co, Ni;n = 2−12, 14, 18) are obtained using all-electron density functionaltheory calculations at the general gradient approximation level. Ondoping an N atom into the pure M n clusters, theground-state structures, binding energies of the resulting mixedclusters have changed but the average M–M bond lengthdoes not obviously change except for Fe2N, Co7N and Ni7N.The doping N atom prefers surface sites except for n = 14 and 18.The results also show the enhanced stability for M n Nclusters compared with that of the corresponding pure M n clusters. The large energy gaps between the highest occupiedmolecular orbital and the lowest unoccupied molecular orbital forFen N (n = 6,12), Con N (n = 3,5,7,9,11) and Nin N(n = 3,6,11,14) clusters indicate their high chemical inertness.Moreover, it has also been found that the total spin magneticmoments of all the M atoms increase slightly for: M =Fe, n = 9,12,14; M = Co, n = 8,9,11,18; and M = Ni,n = 3,11,12.

This paper shows that a suitable design of a corrugation-pitch-modulated (CPM) distributed-coupling-coefficient (DCC) distributed feedback (DFB) laser structure can strongly improve the mode selectivity $(\mathfrak{G})$ and the flatness $(\mathfrak{F})$ of DFB laser structures in order to ensure the required criteria for single longitudinal mode operation ( $\mathfrak{G}$ ≥ 0.25 and $\mathfrak{F}$ ≤ 0.05), through an extended range of current injection. It is shown that a symmetric structure should be used in order to accomplish the requirements imposed by the modern optical communication systems.Photon and carrier rate equations have been used in order to evaluate the performance of the proposed laser structure in the above-threshold regime. The variations of $\mathfrak{G}$ , $\mathfrak{F}$ , the lasing wavelength, the emitted power (P) and the side-mode-suppression-ratio (SMSR) with the current injection (I) have been evaluated.For I = 5 I th , where I th is the laser threshold current, substantial improvements in $\mathfrak{G}$ (3.8 times better), in $\mathfrak{F}$ (2 times better), in P (15% higher) and in the SMSR (about 3.4 dB higher) are achieved in the proposed CPM-DCC-DFB laser when compared to an optimised CPM-DCC-DFB laser referred elsewhere. The improvements are even better when compared to the standard QWS-DFB laser.

The cathodoluminescence spectrum of n-GaN crystal has been studied with emphasis placed on its self-absorption behavior. An improved analysis of cathodoluminescence spectral shift with electron penetration depth is shown, according to the following approach: (i) a main band and a sub-band, both of Gaussian nature, are used for spectral convolution; (ii) the observed absorption edge is still described in terms of the Urbach rule, but the Urbach tail is experimentally retrieved by directly using the absorption spectrum (at low energies) obtained from standard cathodoluminescence spectra; (iii) an experimental approach is used to retrieve the actual morphology of the cathodoluminescence probe.

In this article we present an alternative explanation of the phenomenon of wire fragmentation under high transient currents based on classical electromagnetism. We also explain how this phenomenon can be utilized as a primitive example of low energy-high power disruptive phenomena that can affect even nuclear matter.

Analysis of applied magnetic field and electrical current in Magnetohydrodynamic (MHD) accelerator due to electrical efficiency has been numerically investigated. Studies were carried out using air plasma as a working gas in equilibrium condition. Composition of simulated air-plasma consists of two species, N2, and O2, with concentration of 1 mol and 0.284 mol, respectively. The working gas is seeded with potassium and seed fraction is 1% by weight of all gas, which corresponds to 0.949% in mole ratio. In order to solve the set of differential equations with MHD approximations, the MacCormack scheme is employed. The Magnetohydrodynamic Augmented Propulsion Experiment (MAPX) channel designed and developed by NASA MSFC is used to investigate the MHD accelerator performance. Numerical results show the characteristic of MHD accelerator electrical efficiency with variation of different applied magnetic field and electricalinput.

A device for measuring total electron yields in the energy range 4–65 keV from conductor was set up successfully, which was made up of electron gun system, vacuum system and electrical system. By the pulse electron gun method, the total electron yields in the energy range 4–65 keV from silver were measured, based on the relation between the secondary electron yield and total electron yield at high incident electron energy from metals, the secondary electron yields in the energy range 10–65 keV from silver were deduced. Total electron yields measured with the device were compared with theoretical values, and the deduced secondary electron yield were compared with several authors' values, the results were discussed and a conclusion was drawn that the deduced secondary electron yields and the total electron yields from silver measured with the device are credible.

The eddy current testing method is widely used to evaluate conductive pieces. This method requires an adequate mathematical model which is able to describe the complicated interactions between the source and induced currents, primary and secondary, the fields and the flaws in materials. This paper describes a model which predicts the apparent changes in the impedance of an absolute ferrite-cored probe in axially symmetric non destructive testing (NDT) configurations. Originally, this model is based on coupled electromagnetic quantities principle. To include the contribution of the magnetic environment, the state variable chosen is the current because the magnetic magnetization is replaced by the fictional equivalent currents. The obtained modelling results are validated by comparison to finite element computations. Once validated, the suggested model is not only applied to calculation of probe's impedance in the presence of a defect inside the load but it is also applied to determine geometrical and physical characteristics of the eddy current non destructive testing (ECNDT) device. This half-numerical technique with a very weak time of simulation can be used for the design of new probes and offers a simple solution to the inversion problem. The model is implemented within a software tool (CECM: coupling electromagnetic circuits method) developed in MATLAB environment.

Mechanical abrasion is a phenomenon which commonly occurs during the application of polar-molecular electrorheological (PMER) fluids. We experimentally investigate its effect by milling PMER particles for different times. We find that this effect can significantly reduce electrorheological effects of PMER fluids made of butyrolactone-modified TiO2 particles. This reduction results from the reduced interaction between PMER particles due to the loss of polar molecules on the surface of TiO2 particles. It is further revealed that adding proper amount of suitable polar molecules to the host fluid may compensate for the reduction of yield stress which can be about 100% at high electric fields.