The glass formation and divitrification of a-Se80Te19.5M0.5 (M = Ag, Cd, In, Sb) alloys were studied by Differential Scanning Calorimetry (DSC). A comparison of various simple quantitative methods to assess the level of the stability of these glassy alloys is presented. All of these methods are based on characteristic temperatures such as the glass transition temperature (T g ), on-set crystallization temperature (T o) at which crystallization begins, peak crystallization temperature (T c ) at which the crystallization rate is maximum and melting temperature (T m ). The Hruby number (H r ), which is the strong indicator of Glass Forming Tendency (GFT) and thermal stability parameter (S) representing resistance to divitrification have also been evaluated for these glassy alloys. The stability criteria based on Arrhenius dependence of rate constant K(T) are also studied. The stability of these glasses has been evaluated experimentally and correlated with the activation energy of the crystallization by the kinetic K(T) criteria and it is compared with S criterion.

GaN is grown on Si-face 4H-SiC(0001) substrates using remote plasma-assisted metalorganic chemical vapour deposition (RP-MOCVD). The pre-dissociation of nitrogen by the remote plasma is used for lowering the deposition temperature to approximately 700 °C. Remote plasma processing is also used for SiC surface pre-treatments including a low-temperature atomic hydrogen cleaning (by remote H2 plasma) and nitridation (by remote N2 plasma). Furthermore, in situ spectroscopic ellipsometry is used for monitoring in real time all the steps of substrate pre-treatments and the heteroepitaxial growth of GaN on SiC. Our characterization emphasis is on understanding the nucleation mechanism and the GaN growth mode, which depend on the SiC surface preparation.

We report the structural and electrical properties of polycrystalline silicon on glass crystallized by using a CW Nd:YVO4 laser. Various microstructures appear on amorphous silicon after a scanning of the laser regardless of the crystallization process parameters such as laser power and scan speed. The crystallized region could be characterized by their grain size as 3 distinct regions; RTA-SPC (rapid thermal annealed-solid phase crystallization) region, small-grain region and SLC (sequential lateral crystallization) region with very large grains of ~10 μm. To verify its electrical properties, p-ch TFTs were fabricated on the 3 different regions. The characteristics of TFTs on SLC region were superior to those on other regions and average performances of SLC poly-Si TFTs were $u_{\rm fe} = 132$  cm2/V s, $V_{\rm th} = -4.6$  V, S.S. = 0.5 V/dec, and $I_{\rm off} =\,\sim 1$  pA/μm at $V_{d} = -10$  V, respectively.

In this paper, we present the theoretical and experimental results of the influence of a charge trapped in ultra-thin oxide of metal/ultra-thin oxide/semiconductor structures (MOS) on the I(Vg) current-voltage characteristics when the conduction is of the Fowler-Nordheim (FN) tunneling type. The charge, which is negative, is trapped near the cathode (metal/oxide interface) after constant current injection by the metal (Vg<0). Of particular interest is the influence on the $\Delta Vg$ (Vg) shift over the whole I(Vg) characteristic at high field (greater than the injection field (>12.5 MV/cm)). It is shown that the charge centroid varies linearly with respect to the voltage Vg. The behavior at low field (<12.5 MV/cm) is analyzed in référence A. Aziz, K. Kassmi, Ka. Kassmi, F. Olivié, Semicond. Sci. Technol. 19, 877 (2004) and considers that the trapped charge centroid is fixed. The results obtained make it possible to analyze the influence of the injected charge and the applied field on the centroid position of the trapped charge, and to highlight the charge instability in the ultra-thin oxide of MOS structures.

Optical constants of 2,3-bis-(N,N-1-naphthylphenylamino)-N-methylmaleimide (NPAMLI) thin film grown on silicon substrate by thermal evaporation were investigated using variable angle spectroscopic ellipsometry (VASE). Accurate refractive index n and extinction coefficient k are reported in the energy range of 1.0 to 5.0 eV. Cauchy model, one-oscillator Lorentz model, and six-oscillator Lorentz model were used to fit the experiment data. The optical gap of NPAMLI and the visible absorption peaks at 2.35 and 2.87 eV were also derived from the VASE spectrum.

A convenient way is given in this paper to calculate the effective secondary electron emission coefficient (γ $_{\it eff}$ ) of protective layers in AC-PDP by fitting breakdown voltage curves. Based on the analysis of chemical kinetics of gas discharging in Plasma Display Panels, we deduced an empirical equation of self-sustaining discharge condition for Penning gas mixture in terms of Townsend breakdown criteria. It was used to calculate the breakdown voltage curves of Ne-Xe/MgO, Ne-Ar/MgO, Ne/MgO, Ar/MgO and Xe/MgO in a testing macroscopic discharge cell of AC-PDP. The effective secondary electron emission coefficients were derived by comparing the breakdown voltage curves obtained from the empirical equation with the experimental data of breakdown voltages. The γ $_{\it eff}$ results showed a good conformity with the secondary electron emission coefficients in literatures. The empirical equation can be used as a convenient approach to research gas discharge characteristics and the effective secondary electron emission behaviors in plasma display panels.

We propose a novel calorimetric tunneling (CT) experiment allowing exact determination of heat generation (or heat sinking) in individual tunnel junction (TJ) electrodes, which opens new possibilities in the field of design and development of experimental techniques. Using such an experiment we have studied the process of heat generation in normal-metal electrodesof the vacuum-barrier tunnel junction (VBTJ).The results show there exists a dependenceof the mutual redistribution of the heat on applied bias voltageand the direction of tunnel current, although the total heat generatedin the tunnel process is equal to the Joule heat, as expected. Moreover, the present study indicates generated heat representsthe energy of non-equilibrium quasiparticles coming from inelastic electronprocesses accompanying the process of elastic tunneling.

The present work aims at studying mainly the wall shear stress ofa laminar steady flow of an incompressible Newtonian fluid whichis conveyed through a collapsed tube with a straight centreline.This tube is composed of a tapered segment, a contact segmentwhere the opposite walls touch and a reopening segment. The tubegeometry and steady flow characteristics are obtained frommeasurements in a collapsed tube. The Navier-Stokesequations associated with the classical boundary conditions aresolved using the finite element method. The tridimensional flowresults from the tube configuration. In particular, the flowconsists of two side-jets due to two tear-drop shaped outerpassages in the downstream contact segment associated withreversed flow. In order to compute both the stream-wise andcross-wise components of the shear stress on the wall, a localbasis is defined in each wall node. Downstream of the contactsegment, flow is separated in two jets which are studied thoughthe help of the velocity field and the wall shear stress.

Textile cardiovascular prostheses are tubular structures made of polyester filaments. They present particular mechanical properties linked to wavy form of their walls allowing them to stretch under pressure. Pulsatile blood flow was studied in a moving walls vascular prosthesis. First, an image processing device was used to measure prosthesis displacement under air pressure in an free end impregnated textile prosthesis. Then, fluid-structure interaction is simulated with a numerical computation code allowing to couple prosthesis walls motion with blood flow. Navier-Stokes equations governing fluid flow are numerically solved with N3S code based on finite elements method. The numerical process is based on the Arbitrary Lagrangian Eulerian (ALE) formulation allowing moving domains. The obtained results showed a particular distribution of blood flow velocities and shear stress near the graft walls. The flow velocity distribution near a prosthetic surface is strongly influenced by the crimping morphology and deformation. A local flow analysis is imperative to understanding pathologies implying hemodynamic factors and to optimize the prosthesis design.

Composites studied in this work are the associations of aluminosilicates and 13% of calcium phosphates. These composites present great interest. They are destined to be applied in biomedical field, particularly in orthopedic or jawbone surgery. Calcium phosphates are composed of HA (hydroxyapatite) and TCP (tricalcic phosphate). The success of synthesised bony biomaterials depends on two determinant factors: the porosity (which facilitate the cells deposition and the vascularisation) and the compressive strength (which permits the support of body charge). In this way, a statistical experimental design was employed to quantify the influence of these two synthesis parameters. It concerns the effect of the K2O/SiO2 molecular ratio (X 1) and the effect of the calcium phosphate (HA/TCP) weight % (X 2). The K2O/SiO2 molecular ratio characterises the synthesis of the aluminosilicate. It varies between two limit levels: the stoichiometric ratio K2O/SiO2 = 0.54 corresponding to: $X_{1 }= - 1$ and the ratio K2O/SiO2 = 0.80 corresponding to $X_{1 }= 1$ . In bony biomaterials field, various calcium phosphates are commonly used as biomaterials. In our previous works, the influence of the commercial hydroxyapatite HA and tri-calcium phosphate TCP (13 wt%) addition was investigated. To study the effect of calcium phosphate composition, the weight percentage of mixing HA and TCP varied between two levels: the composite aluminosilicate with 13 wt% of HA ( $X_{2 }= -1$ ) and the composite aluminosilicate with 13 wt% of TCP ( $X_{2 }= 1$ ). Eight samples were studied. The statistical experimental design predicted answer surfaces for compressive strength and percentage of porosity. After the validation of models, it was possible to determine composite which presents best compromise between percentage of porosity and compressive strength. This composite will be evaluated by “in-vitro” and “in-vivo” studies to investigate its potential for forthcoming applied as biomaterial.