Complex scattering amplitude functions of a small metamaterial spheroid are derived. The Mueller matrix solution for polarimetric bistatic scattering from a layer of random metamaterial small spheroids is then constructed. Bistatic scattering of metamaterial and dielectric spheroids are numerically calculated. Linearly co-polarized backscattering coefficients $\sigma _{hh} $ , $\sigma _{vv} $ and $\sigma _{hh} -\sigma _{vv} $ are presented to show the dependence upon frequency. The co-polarized and cross-polarized backscattering coefficients and polarizability degree of a layer of non-uniformly oriented metamaterial spheroids under illumination of an elliptic polarized plane wave are numerically simulated. Effects of metamaterial parameters on scattering pattern and scattering mechanism are interpreted. Numerical results indicate that the bistatic scattering of metamaterial particles is enhanced largely and demonstrates asymmetric directivity. Meanwhile, polarized difference of $\sigma _{hh} -\sigma _{vv} $ strongly varies with frequency due to constitutive dispersion of $\varepsilon (\omega )$ and $\mu (\omega )$ .

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.

The forward current-voltage (I-V) characteristics of Au/n-GaAs Schottky barrier diodes (SBDs) have been studied over a wide temperature range (80–300 K). The barrier height inhomogeneities by assuming a Gaussian distribution of barrier heights at the interface were observed. The evaluation of the experimental I-V data reveals a non-linear increase of the zero-bias barrier height ( $q\Phi _{0}$ ). To remove the spatial inhomogeneity of the barrier height based on small regions or patches and to increase the barrier height compared to the reference sample Au/n-GaAs, the front surface of the n-type GaAs semiconductor has been oxidized by the anodic oxidation method and metal/insulating/semiconductor (MIS) Au/n-GaAs SBDs have been formed. The ln( $I_{0}/T^{2}$ ) versus 1/T and $q\Phi _{0}$ versus T plots of the MIS have exhibited the linear behavior in the temperature range of 80–300 K. Thus, the I-V data of the MIS diodes have obeyed the interfacial layer model due to the interfacial layer and it has been concluded that the inhomogeneity of the barrier height can be disappeared by a formed interfacial layer at the metal and semiconductor interface.

In this work, we simulate and optimize the photocurrent densities in a model of an n-p-n-p type thin film multilayer silicon solar cell for space applications. The incident light penetrates the cell perpendicularly to the junctions. The electrodes tailored inside the structure connect the n-layers together and the p-layers together. The equations giving the photocurrent density produced in each abscissa of the structure was developed. We used Matlab software to simulate and optimize the different parameters of the model. The results of simulation show that the optimized n-p-n-p silicon multilayer solar cell could deliver a photocurrent density of more than 46 mA/cm2 under Air Mass 0 (AM0) solar spectrum (solar constant of 1.36 KW/cm2) and that the photocurrent density produced by the n-p-n-p multilayer silicon solar cell is at least 10% higher than the photocurrent density produced by the simple n-p junction solar cell. We also show that the most important components of the total photocurrent densities (94%) is due to the minority carrier collection which happens on both side of the three space charge regions tailored inside the cell.

Indium tin oxide (ITO) is widely utilized in numerous industrial applications due to its unique combined properties of transparency to visible light and electrical conductivity. ITO films were deposited on glass substrates by an electron beam evaporation technique at room temperature from bulk samples, with different thicknesses. The film with 1500 Å thick was selected to perform annealing in the temperature range of 200–400 °C and annealing for varying times from 15 to 120 min at 400 °C. The X-ray diffraction of the films was analyzed in order to investigate its dependence on thickness, and annealing. Electrical and optical measurements were also carried out. Transmittance, optical energy gap, refractive index, carrier concentration, thermal emissivity and resistivity were investigated. It was found that the as-deposited films with different thicknesses were highly absorbing and have relatively poor electrical properties. The films become opaque with increasing the film thickness. After thermal annealing, the resistance decreases and a simultaneous variation in the optical transmission occurs. A transmittance value of 85.5% in the IR region and 82% in the visible region of the spectrum and a resistivity of 2.8 $ \times\, 10^{-4}\,{\rm \Omega}$ Cm were obtained at annealing temperature of 400 °C for 120 min.

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.

W-Cu-W sandwich coatings are prepared by d.c. magnetron sputtering and the film density is evaluated by RBS and scanning electron spectroscopy measurements. In order to improve the film density up to the bulk density and obtain a dense metallic coating, it is necessary and effective to optimize the deposition parameters, such as, increasing target power and decreasing Ar working pressure. The reduction of the film density from its bulk density is induced by microstructure change and incorporated impurity gas, such as oxygen and argon. When film density is increased, oxygen contamination, due to wall desorption or sample storage in air, decreases.

The effect of both annealing and In content on the properties of ZnO films prepared by electron beam evaporation were investigated. The evaporation was carried out at room temperature from bulk samples prepared by sintering technique. X-ray diffraction showed that the structure of ZnO-In2O3 films depends on both the In content and annealing temperature. Amorphous, highly transparent and relatively low resistive films which can be suitable for the usage as transparent electrode of organic light-emitting diode were obtained upon annealing at 300  $^{\circ}$ C. Partially crystalline, highly transparent and highly resistive films which can be used in piezoelectric applications were obtained upon annealing at 500  $^{\circ}$ C. For each composition the refractive index has no monotonic variation upon increasing annealing temperature.

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.

Amorphous thin films of Se $_{80-x}$ Te20Pbx (0 < x < 2) have been prepared by thermal evaporation. The effect of 40 MeV 28Si5+ ion irradiation on the electronic conduction of Se $_{80-x}$ Te20Pbx (0 < x < 2) thin films has been investigated. The DC electrical conductivity of the films increases by two to three order of magnitude with increase in irradiation fluence from 1012 to 5×1013 ions/cm2. The DC activation energy of conduction also increases with increase in irradiation fluence. Results have been explained on the basis of structural disorders and defects formed due to heavy ion irradiation.

Copper (260 nm) and Ag (1000 nm) films deposited on glass substrates, at different substrate temperatures. Their optical properties were measured by ellipsometry (single wavelength of 589.3 nm) and spectrophotometry in the spectral range of 200–2600 nm. Kramers Kronig method was used for the analysis of the reflectivity curves of Cu and Ag films to obtain the optical constants of the films, while ellipsometry measurements was carried out as an independent method. The influence of substrate temperature on the microstructure of thin metallic films [Structure Zone Model (SZM)] is well established [Movchan and Demchishin, Phys. Met. Metall. 28, 83 (1969); Thornton, J. Vac. Sci. Technol. 12, 830 (1975); Savaloni and Bagheri Najmi, Vacuum 66, 49 (2002); Savaloni and Player, Vacuum 46, 167 (1995); Savaloni et al., Vacuum 43, 965 (1992)]. The Effective Medium Approximation (EMA) analysis was used to establish the relationship between the SZM and EMA predictions. Good agreements between SZM as a function of substrate temperature and the values of volume fraction of voids obtained from EMA analysis, is achieved; by increasing the substrate temperature the separation of the metallic grains decreases, hence, the volume fraction of voids decreases and denser films formed. The predictions of the Drude free-electron theory are compared with experimental results for dielectric functions of Cu and Ag films of different substrate temperature. The real part of the dielectric constant is decreased with increasing the substrate temperature, while the imaginary part of the dielectric constant increased with temperature for both materials over the whole energy range measured, including intraband and interband regions. The increase of the imaginary part in the interband region suggests a temperature and frequency dependence of the relaxation time in the Drude model, namely $\tau ^{-1}\left( \omega \right)=\tau _0^{-1} +\beta \omega ^2.$

The microstructure and morphology evolution in nanocrystalline PbSe films chemically deposited on GaAs(100) and GaAs(111) substrates were compared to PbSe films on Si(100) under the same conditions. On GaAs substrates, dense and continuous PbSe films were obtained. We show that the temperature dependent morphological changes on GaAs substrates occurred as a result of increased sample thickness due to higher reaction rates. Notably, the deposition of PbSe on Si(100) did not lead to continuous films and no preferred orientation was observed. The improved wetting between PbSe and GaAs appears to be a key factor responsible for the differences observed on the two substrates.

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 general-purpose formulae for the nonretarded two-dimensional Green functionin the case of arbitrary geometrical shapes of lossy dielectricsis derived by the method of complex variables. Spectral powerdensities of fluctuating electromagnetic fields are determined byreal and imaginary parts of the Green function. Spectralproperties of fluctuating fields in given geometrical domains maybe obtained by appropriate conformal mappings. The applicabilityof the method is illustrated by in comparison with some exactsolutions, in particular, related to a cylinder, to an arbitrarywedge, and to a plane slit. The impact of curved surfaces uponspectral characteristics is analyzed by numerical calculations offields inside the “open” parabolic domain and inside or outside of“close” cylindrical domains as compare with a plane case. Thecontrollability of spectral properties by a local curvature ofsurface is demonstrated.

An optical apparatus designed for the mapping of binaryor ternary phase diagrams is described. A polychromatic polarizedlight illuminates a sample and the rotation of its polarization ismeasured with a spectrometer for various magnetic fields. Themeasured parameters are the natural and magnetic rotatory power ofthe sample which allow the concentration retrieval of everycompound to be done. Results show that the apparatus issuitable for correct positioning of single phase boundary on theternary water - n-dodecyl-β-d maltoside - sodium chloridesystem.

The intracavity photon density is assumed to be Gaussian spatial distributions and the nonlinear loss that is due to second-harmonic generation (SHG) to the photon-density equation is given under Gaussian spatial distributions in the rate equations for a diode-pumped passively Q-switched intracavity-frequency-doubling Nd:GdVO4/KTP laser with Cr4+:YAG saturable absorber. These space-dependent rate equations are solved numerically. The dependences of pulse width, pulse repetition rate, single-pulse energy and peak power on incident pump power are obtained for the generated-green-laser pulses. In the experiment, a diode-pumped passively Q-switched intracavity-frequency-doubling Nd:GdVO4/KTP laser with Cr4+:YAG saturable absorber is realized and the experimental results are consistent with the numerical solutions.

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.

In this paper, we analyze in detail the etching parameters that are used for manufacturing gold tips for tip-enhanced near-field optical microscopy and spectroscopy. From the current variation versus time, we first demonstrate that the sharpest tips are obtained if the etching is stopped at a specific time where the curve presents an inflexion point. We then analyze the influence of the concentration of the etching solution and the applied voltage on the roughness and the tip apex. As a result, we propose a set of parameters allowing for reproducible production of gold tips with 20 nm radius of curvature.

Using an Atomic Force Microscope (AFM) operated in contact mode under ambient conditions, we have tried to resolve atomically sharp cracks perpendicular to the basal plane of muscovite mica. However, although tip radius of probes of less than 10 nm allowed a lateral resolution of 0.7 nm and the tip-sample adhesive force has been minimized, our experimental results demonstrate that the molecular structure of crack tips can't still be resolved. Even worse, sometimes the tip-sample friction can disrupt the region around the crack tip. This thus leads to the conclusion that one will fail to resolve atomically sharp cracks under ambient conditions by contact AFM. The inability is due to low lateral resolution of contact AFM and strong tip-sample interaction force under ambient conditions. New techniques of scanning samples in liquids and UHV non-contact AFM both of which have true atomic resolution are strongly recommended for future studies.