The effect of annealing on the physical properties of DC and RF sputtered ITO thin films has been investigated. Two series of samples were deposited onto glass substrates, the first one consists of several In2O3:Sn (ITO) prepared by DC reactive sputtering with different partial pressure of oxygen (ppo); in the second one, the ITO samples were done by RF sputtering with different RF powers. Annealing experiments were done in various conditions: in air, in vacuum and in Ar atmosphere for temperatures in the 100 °C to 500 °C range. Structural properties were studied using Scanning Electron Microscopy (SEM), the usual X-ray diffraction (XRD) and also in-situ X-ray diffraction where X-ray spectra were recorded while the sample was being annealed. The optical properties were inferred by means of a spectrophotometer with wavelength in the 200–900 nm range. It was found that, for DC sputtered films, annealing favours the existing texture either $\langle 111\rangle$ or $\langle 100\rangle$ ; while, for the RF sputtered ones it always favours the $\langle 111\rangle$ texture. Annealing induced some similar changes in both series of samples such as the increase of grain size, the decrease of the strain and the electrical resistivity. The values of the optical transmission decreases after annealing at temperatures T = 400 °C and T = 500 °C for the DC and the RF sputtered films respectively. The decrease seems to be more important in the DC than in the RF sputtered ITO films.

Raman spectra of a variety of polymorphous (pm-Si:H) and amorphous silicon (a-Si:H) samples deposited by plasma enhanced chemical vapor deposition (PECVD) at different pressures were recorded in the range of 150 cm-1 to 750 cm-1 using a 514 nm excitation source. A comparison of Raman spectra between a-Si:H and pm-Si:H samples reveals significant differences. The Transverse Optical (TO) peak in case of pm-Si:H is asymmetric and shifted to higher wave numbers. In the literature, discrepancies between predictions of various quantum confinement models and experimental spectra have typically been attributed to either strain or negligible fraction of nanocrystallites. We show that a quantum confinement model along with a Gaussian size distribution is able to accurately predict particle size of nanocrystallites embedded in the amorphous matrix. The crystallite size and size distribution obtained by fitting the TO peak is consistent with high-resolution transmission electron microscopy observations. In our case typical mean crystallite size obtained is about 3 nm with FWHM of the distribution varying in the range 0.2–1 nm. A comparison of ratio of heights in TA and TO peaks of a-Si:H and pm-Si:H material indicates that pm-Si:H as a material has higher medium range order (MRO). This ratio has been used to compare the degree of MRO in pm-Si:H samples prepared under different conditions. Thus, we demonstrate that Raman Spectroscopy along with our model can be used to obtain the crystallite size distribution and provide a measure of degree of medium range order.

Current-voltage dependence for In2O3-SrOceramics contains three regions: linear at low voltages,superlinear at intermediate voltages (current is increasedstronger than voltage) and sublinear at higher voltages (currentis increased weaker than voltage). The appearance of sublinearregion after superlinear one cannot be explained by the existingtheory. Based on the experimental data (electrical measurements,SEM and XPS) a modified grain-boundary model is suggested. In themodel the additional adsorption of oxygen due to a capture ofelectrons at the grain-boundary states is assumed. Accordingly,the barrier height is increased and current is saturated.Calculated current-voltage dependences correspond experimentallyobserved ones.

Ultra-wide band antennas can be characterized by the time-domain impulse response. This paper introduces an approximate form of the impulse response that can be calculated by applying the method of moments to the Freedholm integral equation of convolution. Numerical results are compared to those obtained using the traditional frequency-domain approach. The validity of the approximate impulse response and the application constraints are also discussed. It is shown that the time-domain approach is faster than the frequency-domain approach while the accuracy is preserved.

Organic field-effect transistors (OFETs) in which the active semiconductor is made of polycrystalline octithiophene (8T) were fabricated and characterized. Several methods have been used to extract the parameters of the polycrystalline (8T) transistors as function of gate voltage at room and at low temperatures. These parameters such as the mobility, the threshold voltage, contact resistance and density of traps are extracted from the current-voltage characteristics of OFETs. The first method consists of deriving the drain current as function of gate voltage (transconductance), leading to the so-colled field effect mobility. It appears that the data must be corrected for the substantial source and drain contact resistance. In the second method, the carrier mobility has been corrected for the contact resistance. It is found to increase quasi linearly with gate voltage. Therefore, the contact resistances have been directly extracted from the experimental channel conductance. In the third method, data are interpreted according the multiple thermal trapping and release model using a power law dependence of the mobility with gate voltage together with a constant resistance. Finally, using a model where charge transport is limited by trapping and thermal release at localized states located at grain boundaries, the barrier height at grain boundaries in polycrystalline octhithiophene FETs has been estimated. It is shown that is gate bias dependent.

Hydrogenated diamond-like carbon (DLC:H) films were deposited on Si substrates by a methane (CH4)-argon (Ar) plasma enhanced chemical vapor deposition (PE-CVD) technique assisted by carbon (C) sputtering. The deposition rates of DLC:H films increased with increasing Ar gas flow rate under a CH4 gas flow rate, and saturated at large Ar gas flow rates. The dielectric constants varied from 2.2 ε 0 on DLC:H films deposited without Ar gas flow to 6.3 ε 0 on DLC:H films deposited with large Ar gas flow. The C – V curve for the sweep of bias voltages from positive to negative was positioned above that of the return sweep of bias voltages from negative to positive because electrons are injected from Si substrates to the surfaces of DLC:H films. The C – V curve on the returning bias voltage sweep approached that of the going bias voltage sweep accompanying to an increase in dielectric constant.

In this paper, a new SPICE-compatible circuit model for low voltage, low on-resistance power FLYMOSFETs is presented for the first time. In this new structure, the improvement of the on-resistance has been obtained by inserting floating islands in the lowly doped layer. Our modelling is based on device physics, analytical study and on experimental characterization. The inter-electrode capacitances are modelled accurately as nonlinear functions, and good agreement between simulation and measurements is found.

This paper proposes a general applicable numericalalgorithm for the simulation of two dimensional electrode shapechanges during electroforming processes. The computational modelconsists of two coupled problems: electrode shape change ratecomputation and a moving boundary problem. The innovative aspect isthat the electrode shape is computed over a number of predefinedtime steps by convection of its surface proportional with and in thedirection of the local growth rate. Validation of the electrodegrowth algorithm is made by comparison with experimental resultsobtained for the electrode growth in the vicinity of a singularity(incident angle between the electrode and insulator = 180°).Finally an example related to the plating of two adjacent wires inorder to demonstrate the strong features of the applied method willbe presented.

The generalized Mie theory, also known as themultiple-scattering theory, is an analytical method for solving the scattered field by a collection of spherical scatterers. This is the fastest, most reliable method when the wavelength is close to the structure's dimensions. It is applicable to frequency selective surfaces and is the onlymethod for analyzing finite photonic crystals with a large size. We used simplified structures to compare this method with other techniques.

Using both acoustic-optic (AO) modulator and GaAs saturable absorber in the same cavity, a diode-pumped doubly Q-switched c-cut Nd:GdVO4 laser has been realized. This laser can generate the more symmetric pulse with shorter pulse width in comparison with singly AO or GaAs Q-switched laser. We also made a comparison between c-cut and a-cut Nd:GdVO4 crystals and the experimental results shows that the doubly Q-switched c-cut Nd:GdVO4 laser can generate narrower pulse with higher peak power when the incident pump power higher than 3.4 W. The coupled rate equations, in which the spatial distributions of the intracavity photon density and the population-inversion density are taken into account, are introduced to theoretically analyze the experimental results, and the experimental results are in fair agreement with the numerical solutions.

The thermal conductivities of nine different synthetic garnet laser crystals at various temperatures, range from 273 to 393 K have been investigated by instantaneous measurement method. The results show that the thermal conductivity of each crystal decreases exponentially with the temperature increasing. It is notable that, different host crystals, such as YAG, GGG, and GSGG have different thermal conductivity, which is attributed to the crucial influence of crystal structure and composition on the absolute value of their thermal conductivity. Moreover, with respect to the same host crystals, the impurity scattering also results in the change of their thermal conductivities. This is because that a higher concentration of doped ions leads to a more phonon scattering modes, which results in a shorter mean free path of the phonons and a lower thermal conductivity. In addition, different host crystals have various dependences of thermal conductivity on dopant concentration. This works provides reliable and useful information for designing high power, high quality, and high stability laser devices.

Dielectric, impedance, modulus and conductivity studies were performed over temperature 35 °C–600 °C and frequency 45 Hz–5 MHz range on the Lead Potassium Lithium Niobate (Pb4.0K1.0Li1.0Nb10O30, PKLN) ceramics. These studies established the conduction ion motion and polarization mechanism in the material. The dispersive dielectric loss at high temperature reveals the ionic conductivity. From frequency variation of ε l response the pre-factor A(T) and critical exponent n(T) are evaluated, and are used in Jonscher's dielectric dispersion relation for ε' to fit with the experimental data. Complex impedance plots showed a non – Debye type relaxation, are used to evaluate the grain and grain boundary conduction and relaxation activation energies. DC and ac conduction activation energies are estimated from Arrhenius plots. Occupancy of Li+ for C-sites gave a completely filled structure and enhanced the phase transition temperature to 520 °C compared to PKN. This is supported by the conduction activation energy in ferro region is more than the para region. Also, the dc conductivity characterized from bulk resistance and Mll peak frequency. Polaron hoping mechanism at room temperature has been confirmed via the linear variation of the plot log (σ ac – σ dc ) as a function of log ω 2. Stretched exponential parameter, β(0 < β $\leqslant$ 1) has been evaluated from impedance plots, interpreted as a result of correlated motions between the Li+ ions and distribution of dielectric relaxation. Compared the results from different techniques, and discussed the conduction mechanism in the material.

Induction motors optimal design can involve many variables and objectives, and generally requires to make several trade-offs, especially when including the audible electromagnetic noise criterion beyond the usual performance criteria. Multiobjective optimization techniques based on Pareto optimality are useful to help us finding the most interesting solutions and decide which one(s) to adopt. However, it is not always easy to analyse the Pareto-optimal solutions obtained with such methods, especially when treating more than three objectives, and Pareto fronts may contain more data than we might think.This paper briefly describes an analytical model of the variable-speed squirrel-cage induction machine which computes both its performances and sound power level of electromagnetic origin. The model is then coupled to the Non-dominated Sorting Genetic Algorithm (NSGA-II) in order to perform global optimization with respect to several objectives (e.g. noise level, efficiency and material cost). Finally, an optimization problem is solved and analysed, and some useful visualization tools of the Pareto optimal solutions and their characteristics are presented.

A metamaterial with a negative effective index of refraction is made from a three-dimensional hexagonal lattice photonic crystal with a metallic basis embedded in foam. It has been simulated with Ansoft HFSSTM in a frequency range from 7.0 to 12.0 GHz. Simulated results tested experimentally and negative refraction verified in some frequencies. Experimental results are in good agreement with simulations.

Conducting poly(o-toluidine) (PoT) was synthesized from a derivative of aniline (o-toluidine) monomer by chemical oxidative polymerization method. After polymerization, the polymer prepared was then blended with Poly Vinyl Chloride (PVC) to achieve films. FTIR and UV-Visible studies were carried out to get their optical information. The blends were irradiated by Swift Heavy Ion (SHI) beam of 60 MeV C5+ ions with different fluences. Post Irradiation FTIR and UV-Visible spectroscopy were carried out on these films, which revealed changes in the band gap with irradiation. There are also changes in the functional groups, which are confirmed by FTIR spectra. Optical band gap is found to decrease at all fluences and increased with increase in fluence.

Intra-dot inter-layer magnetostatic coupling have been investigated in trilayers which consist of two [Co/Pt] multilayers with out-of-plane anisotropy and different coercivities separated by a thick Pt layer. For single domain nanodots, the strong intra-dot inter-layer magnetostatic interactions manifest as a shift of the soft layer hysteresis loop. The amplitude of this shift decreases when the size of the dots is increased and/or when the temperature is increased. Satisfactory agreement is found between calculations and experimental results.

The shielding of strong electromagnetic fields at power frequency, performed by ferromagnetic plates, is often successfully modelled by the effective reluctivity. This method delivers good results for the RMS value of the shielded field. The following paper shows that a small variation of the magnetization curve (e.g. by taking another material charge) can strongly influence the shielded field. The field calculation is performed by the Finite Element Method (FEM), where for the interior plate region a) finite elements and b) non-linear Impedance Boundary Conditions (IBC) are used which circumvents the need to discretize the shielding plate.

Polycrystalline halosulphate phosphors are prepared by a wet chemical method. Strong thermoluminescence (TL) was observed in KZnSO4Cl, KMgSO4Cl, Na3SO4F and NaMgSO4F hosts. In these hosts Ce, Dy; Ce, Mn and Ce, Tb the Ce3+ ions acting as sensitizers and Dy3+, Mn2+and Tb3+ ions as activators. The TL glow curves of these halosulphate phosphors exposed to γ-rays for 5 Gy at the rate of 0.995 kGyh-1 are described and discussed first time here.

The behaviour of clays is not still well understood. Most information concerning clays has been obtained by techniques which give statistical information on the structure and chemistry. However papers have reported results from scanning and high resolution electron microscopy. This work presents a nanoscopic approach, using electron energy loss spectroscopy (EELS), of different purified clays. EELS permitted to detect all the elements found by classical chemistry at a macroscopic level. In particular it made it possible to determine the Si/Al ratio in kaolinite (Si/Al ~ 1), smectite and illite (Si/Al ~ 2). In all the cases, the K edge oxygen energy loss near edge structure (ELNES) is often similar to that of other clays we studied, but a strong heterogeneity has been observed. It was also possible to highlight an influence of the presence of iron on the profile of the oxygen peak.