The stability of compressed thin films on substrates is discussed in the frame of the Föppl-Von Karman theory of thin plate buckling. The destabilization from pre-existing straight-sided to worm-like patterns is investigated and a critical stress is determined, above which the morphological change of the film occurs. Experimental investigations by atomic force microscopy have been also conducted and the different stages of this evolution have been characterized.

Thin films of Ge20Te80 and Cu6Ge14Te80 of different thicknesses are deposited on glass substrate by thermal evaporation under vacuum. The effect of incorporation of copper in Ge20Te80 film is studied by measuring the optical absorption. The mechanism of optical absorption follows the rule of direct transition. The films are annealed at different elevated temperatures from 370 to 520 K. The measurements were carried on as-deposited and annealed specimens. The optical energy gap (Eg) was found to decrease with increasing the annealing temperatures in the case of Ge20Te80 films. But in the case of Cu6Ge14Te80 films, Eg first increases with annealing temperature up to 410 K, then decreases sharply after further increasing the annealing temperature above the glass transition temperature. The decreases of Eg and the increase of the width of localized states Ee could be attributed to the amorphous - crystalline transformation. The values of optical energy gap Eg are also found to increase with thickness of both two-type films. The effect of films thickness on optical energy gap (Eg) of the films is interpreted in terms of the density of state model of Mott and Davis. The refractive index n, extinction coefficient k and dielectric constant $\varepsilon_{\rm i}$ and $\varepsilon_{\rm r}$ are also calculated for all samples.

In the present work, the stress-impedance and the stress-resistance for Co68.5Fe4.5Si12B15 amorphous ribbon are reported. The stress-impedance decreases with increasing tensile stress. In contrast, the large stress-resistance appears at high frequency. The value of $(R(0)-R(F))/R(0)$ with F = 20g can reach 31.4% at 5 MHz. The mechanism of the stress-impedance effect is also discussed.

Triglycine sulphate, $(\rm NH_2CH_2CO_2H)_3\cdot H_2SO_4$ (TGS), is a ferroelectric crystal widely used in optical properties studies, phase transitions theory as well as test for experimental techniques. Lead monohydrogen phosphate, PbHPO4 (LHP), is a typical representative of the family of ferroelectric schultenites, suitable in testing microscopic theories of ferroelectricity. In this work the so-called high-accuracy universal polarimeter (HAUP) has been used to determine the natural anisotropy in the birefringent crystalline sections (010), obtaining the temperature dependence of optical anisotropy magnitudes of the crystal: gyrotropy, birefringence and optical indicatrix rotation. Our HAUP technique also permits to investigate the electro-optic (EO) coefficients associated to the phases above and below phase transition temperatures.

We describe a home made small angle light scattering apparatus. The detection is based on a high sensitivity 16 bits CCD camera placed in the focal plane of a lens. The apparatus is calibrated in such a way that it allows measurements of the scattered intensity in absolute values as a function of the scattering vector. Carefully characterized latex particle suspensions (determined size distribution and particle density number) are used to test the validity of calibrations. Particle scattering patterns in absolute units show good agreement with computed intensities using Mie theory. The apparatus performances are finally discussed.

The correlation of deposition parameters with output functions when using a novel rotating cryostat (RC) system to produce magnetic materials has been investigated here. In order to do this, an orthogonal design technique was applied for magnetic material production using a resistively heated furnace. The results of orthogonal analysis indicate that the thickness uniformity across the film was not greatly improved, due to the large standard deviation, but an optimum deposition rate was obtained by appropriate choice of control parameters. Furthermore, the orthogonal design process was applied to systematically optimise the production of low coercivity in iron films. The results indicate that the process can be easily optimised.

In this paper the finite-difference time-domain (FDTD) method is reviewed and then used to model and predict the geometric parameters used for the design of the device. The waveguide consists of a periodic array of air gap etched into a silicon (Si) strip on a silicon dioxide (SiO2) layer. The width and the depth of the grooves of the air gap (n = 1) as well as the length of the silicon layer (n = 3.4) are investigated. Using FDTD, the optical parameters are characterized. The effect of the air gap on the field profile distribution of the whole structure is calculated and performed in the range 0.09687 μm –1.55 μm. The field profile, and the response of the microcavity against frequency are calculated from sinusoidal sources. The spectral behavior of the structure is performed and its validity is verified by calculation of the reflectance spectra.

Electrical properties of a device depend primarily on the active dopant concentration; understanding of the activation (annealing) process is crucial for the prediction of device behaviour. The present paper reports results from a computer based simulation approach to improve the breakdown performance of the device by studying the annealing behaviour of boron implanted in silicon. In order to have deep insight of the effect of defect complexes on the device performance, extended defect model has been incorporated in the simulation program. Optimization of annealing time, annealing temperature and dose has been performed, for the first time, incorporating a complete set of process induced defects like {113} defects, interface traps, dislocation loops and the optimization has been validated in terms of the breakdown performance of the device.

The effect of inter particle collisions on a “kinematic” shock wave produced by a velocity gradient in a cold atomic gas is studied, to the end of establishing a connection between such kinematic shocks and the “traditional” fluid dynamic shock front. In order to include the collisional effects we use both a DSMC (Direct Simulation Monte Carlo) model and a Monte Carlo solution of the Bhatnagar-Gross-Krook equation (BGK/MC). The substantial agreement of DSMC and BGK/MC results for a sufficiently high value of the collision frequency proves that the kinematic and thermodynamic descriptions of the shock front can be smoothly joined by scaling this parameter.

The main factors limit the field of the magnetic lenses are the current density σ and the accelerating voltage Vr. Optical properties such as chromatic and spherical aberration have been studied in terms of σ and Vr. Values of the other aberration coefficients for the optimum lens size corresponding to the desired minimum aberration are estimated.

A new approach to determine the displacement field between a reference and a deformed image is introduced. The method is based on a spectral decomposition of the displacement field which is determined through a multi-scale approach. The method is tested here on an artificial example by using computer-generated images devoid of boundary effects (i.e., periodic boundary conditions are used in the image texture and displacement field). The performance of the proposed algorithm allows for the determination of the prescribed displacement field up to machine precision, for a strain field whose trace extends from −50% to 40% with a root-mean-square average of 15%, within sub-minute runs on a standard PC.