Within Silicon Carbide Junction Field Effect Transistor (SiC-JFET) model, body diode is not extensively studied and almost under-researched. Body diode remains a complex device to study particularly during switching transients. In this paper, the JFET body diode is experimentally demonstrated to be a power PiN diode. Finite element method model based on the device geometry and SiC material is used to accurately simulate this diode. Accurate simulations are necessary for analysis and verification purposes. Simulation relies on component models and associated parameters. The paper focuses on a step-by-step extraction procedure for design parameters of the SiC-JFET body diode. A comparative study between experimental data and simulation results is given to validate the device model and associate parameters.

The electronic transport properties of p-type tin selenide (SnSe) grown by direct vapor transport (DVT) technique were investigated via Hall effect in the temperature range 40 <T< 300 K. The temperature dependence of conductivity revealed the existence of impurity energy level in the band gap of the crystal. The temperature dependence of the carrier concentration was analyzed using the single-donor – single-acceptor model. The Hall mobility increases by decreasing temperature up to 120 K and then decreases along with temperature. The observed temperature dependant mobility in the temperature range 120 <T< 300 K and 40 <T< 120 K was found to be limited by homopolar and ionized impurity mode scatterings respectively.

In this work the main effective parameters on the electrical resistivity of copper nitride thin films are investigated. Copper nitride thin films were successfully deposited on glass substrates by reactive dc magnetron sputtering at room temperature but different sputtering time. Working gas was a mixture of argon and nitrogen with equal amounts. The effect of deposition time on the structural, optical and electrical properties of deposited films was investigated. X-ray diffraction measurements show different lattice orientation in the structure of deposited films. By increasing the time of sputtering an orientation change from (100) to (111) can be observed in the films. Film morphology of samples is not changed with the sputtering time. The optical transmittance of deposited films decreases with increasing the deposition time. Results confirm that when the amount of nitrogen in working gas is 50%, we have more (100) planes in the structure of the deposited films, leads to higher resistivity of the films.

The temperature dependence of the electrical conductivity before and after gamma irradiation of hydrogenated amorphous silicon (a-Si:H) films, prepared by the hot wire method, at a dose of 2 kGy of 60Co gamma irradiation are presented and discussed. Fourier transform infrared spectroscopy (FTIR) measurements provide useful information on the characteristics of bond configurations in a-Si:H before and after gamma irradiation. The conductivity increased and the bond configurations changed significantly after gamma irradiation. The results are explained by the filling of shallow donor states and variation of bond type due to migration of hydrogen atoms under the effect of irradiation. The behaviour of the conductivity is consistent with a hopping mechanism. The temperature dependence of the conductivity of a-Si:H exhibits a $T^{-1/4}$ law, instead of the $T^{-1/2}$ law, after gamma irradiation.

Calcium phosphate based biomaterials are widely used in dentistry and as a bone substitutes in orthopedic applications. Calcium pyrophosphate (CPP) – a type of calcium phosphate and a shortest linear polyphosphate can also be used as a bone graft. Successive applications of theses materials depend on the degree of bio-resorption, mechanical strength and bio-compatibility. Zinc improves the bone activity of osteoblast, promotes the bone regeneration and also stimulates enzyme activity. In the present study Zn doped calcium pyrophosphate dihydrate (Zn-CPPD) nanoparticles were synthesized using surfactant mediated approach with varying [Zn]/[Ca] molar ratio as 0% (pure CPPD), 2%, 5% and, 10%. The crystalline nature and the average crystallite size was studied by Powder XRD. Zinc doping was confirmed by EDAX. The TEM study indicated that pure and Zn doped CPPD nanoparticles were in the range from 4 nm to 40 nm. The presence of various bonds was confirmed by FT-IR spectroscopy. The amount of water of hydration and the thermal stability was studied by thermo-gravimetry. Formation of other phases on heating CPPD at $900^{\circ}$ C and $1250^{\circ}$ C were identified by the powder XRD. Substitution of Zn content significantly affects the crystallinity and thermal stability of nanoparticles. The results are discussed.

Zinc oxide (ZnO) nanorods, with different aspect ratios, were synthesised at room temperature via an inexpensive physico-chemical route. The source material was a mixture of zinc acetate dihydrate [ Zn (CH3 COO)2  $\cdot$  2H2O] , cetyl-trimethyl ammonium bromide [ C19H42BrN] , and sodium hydroxide [NaOH]. The length of the nanorods, as a result of restricted directional growth, was controlled by means of varying the molar ratios of the reactants. As revealed by X-ray diffraction measurements, the as-grown ZnO nanorods exhibited wurtzite crystalline phase, with preferred crystallographic orientation along (101) plane. The visual evidence of the formation of ZnO nanorods was confirmed by transmission electron microscopy studies. The photoluminescence spectra of the ZnO systems show two prominent peaks: a sharp peak located at ~375 nm (UV band) and a broad band peaking at~480 nm (green band). The UV-to-green PL intensity ratio was found to be improved with enhanced aspect ratio. The aspect ratio dependent tunable optical responses would provide better insight to understand the radiative and non-radiative processes in elongated nanosystems.

This paper studies numerically the temperature reached by atomic force microscope tips illuminated by femtosecond laser pulses, in which the laser focusing dependence of tip heating is investigated in detail and the laser heating effects on different tips are discussed too. The results show that tip heating can be significantly reduced if the femtosecond laser is focused tightly on the tip apex.

Using spectroscopic and small angle X-ray scattering analyses, temporal evolution of ionic and neutral silver clusters inside and on the surface of a glass matrix has been studied during the ion-exchange process. It is found that in the beginning of the ion-exchange process the ionic clusters (Ag $_{N}^{+}$ ; where N is the number of atoms of the ionic silver cluster) form and start to grow. But, with continuation of the process the generated ionic silver clusters begin fragmentation and resizing which, in turn, results in modification of the interaction with the glass matrix. Our results show that, longer ion-exchange processing time results in re-growing of the ionic silver clusters. Simultaneously, the index of refraction of the ion-exchanged glass first increases, then decreases and increases again. Our findings imply that, there is no simple linear relation between the index of refraction and the ion-exchange duration time. Some of the ionic clusters may transform to neutral ones by absorbing electrons available in the glass matrix. X-ray and AFM analyses confirm that, at the same time, some neutral silver nanoparticles form on the surface of the samples, and their evolution follows the evolution of the forming ionic clusters. Resizing, movement toward the surface and aggregation of the clusters, are the most important consequences of the interaction of the forming clusters with the glass matrix observed in this study.

We study resonant tunneling through a layered medium with a passive negative index medium (NIM) slab as a constituent layer. Using a causalmodel for susceptibilities with the parameters of a recently reported metamaterial [G. Dolling, C. Enkrich, M. Wegener, C.M. Soukoulis, S. Linden, Opt. Lett. 31, 1800 (2006)] we show that resonant tunnelling and the associated delay are mostly suppressed. This is in sharp contrast with the naive approach of retaining phase velocity dispersion with arbitrary low losses, predicting sharp resonances with large associated delays. This is shown to be a nontrivial issue because of the necessity of losses for NIM behaviour, while their presence spoils the quality factor of the resonant devices.

The vortex dynamics of (Y, Nd)Ba2Cu3O7−δ ((Y, Nd)123) superconductors have been studied using magnetic relaxation measurements obtained at different sweep rates. The temperature dependence of the dynamic relaxation rate (Q) is found to be not vanishing at T = 0 K, and also showed well developed maxima becoming broader and tending to move to higher temperatures with decreasing magnetic field. At temperatures close to the critical temperature (T c ), Q(T) showed well-developed minima becoming deeper and tending to move to lower temperatures with increasing field. These minima appeared to occur approximately at the same reduced temperature position [ T/T c ]as that of oxygen-controlled-melt-grown (OCMG)-Nd(123) samples, thus providing further support for pinning similarities between both systems. Both the field dependence of the characteristic pinning energy [ U c ]and relaxation rate showed significant inconsistency with the collective pinning theory but full agreement with the results of [Perkins et al., Phys. Rev. B 54, 12551 (1996)].

The formation of the chemical products produced in an atmospheric glow discharge fed by a N2-CH4 gas mixture has been studied using Fourier Transform InfraRed (FTIR) and Optical Emission Spectrometry (OES). The measurements were carried out in a flowing regime at ambient temperature and pressure with CH4 concentrations ranging from 0.5% to 2%. In the recorded emission spectra the lines of the second positive system CN system and the first negative system of N2 were found to be the most intensive but atomic H $^{\alpha}$ , H $^{\beta}$ , and C (247 nm) lines were also observed. FTIR-measurements revealed HCN and NH3 to be the major products of the plasma with traces of C2H2. These same molecules have been detected in Titan's atmosphere and the present experiments may provide some novel insights into the chemical and physical mechanisms prevalent in Titan's atmosphere with these smaller species believed to be the precursors of heavier organic species in Titan's atmosphere and on its surface.

The elastic and thermodynamic properties of fcc-6LiF under high temperatures and pressures are investigated using the ab initio method and quasi-harmonic Debye model. The lattice constant of 6LiF at ground state is a little larger than that of LiF. When pressure is less than 10 GPa, crystal lattice is compressed easily at low temperature, and when P> 10 GPa, lattice can be compressed easily at high temperature. C 11 increases with pressure and reduces with temperature sensitively. C 12 and C 44 raise or decrease just a little with increasing pressure and temperature. Heat capacity of different pressure increases with temperature and closes to the Dulong-Petit limit at higher temperatures. Debye temperature decreases with temperature, and increases with pressure. Furthermore, under lower pressure, thermal expansion coefficient raise rapidly with temperature, and the increasing trend will get slow at higher pressure.

This paper deals with a technique for calculating the 3D E-field components knowing only the two components (H x and H y ) of the H-field in near-zone. The originality of the under study technique lies on the possibility to take into account the evanescent wave influences. The presented E-field extraction process is based on the exploitation of the Maxwell-Ampere relation combined with the plane wave spectrum (PWS) method. The efficiency of the proposed technique is evidenced by comparing the E-field deduced from H-field and the own E-field radiated by the association of electrical- and also magnetic- elementary dipoles in different configurations by using Matlab text programming environment. In addition, as a concrete demonstrator, the concept was also validated with the computation of EM-wave radiated by an open-end microstrip transmission line. As result of comparison, very good agreement between the exact E-field and that one extracted from the H-field was realized by considering the near-field scanned at the height, z = 5 mm and 8 mm above the under test structure at the operating frequency, f = 1 GHz. The presented technique can simplify the difficulties about the E-near-field measurement in EMC applications.

Sintered cubic boron nitride (cBN) is widely used in various industrial applications because of its extreme wear and corrosion resistance, thermal and electrical properties. Conventional cBN sintered compacts contain binder materials and the binder materials remarkably affect their mechanical and thermal properties. In this work, polycrystalline cBN (PcBN) compacts were sintered on WC-16 wt.%Co substrates without any sintering agent at static high pressure of 5.0 GPa and temperatures of 1550–1750°C for 3–20 min. Chemical reactions between cBN and substances infiltrated from the substrates occurred during the high pressure and high temperature (HPHT) sintering process. Reaction products and their contents strongly depended on the sintering temperatures and heat treatment times according to the X-ray diffraction (XRD) observations. Scanning electron microscopy (SEM) analysis showed that some samples sintered under some specific conditions had plenty of cBN-to-cBN bonding among cBN grains and homogeneous microstructures. We also found that the formation of the cBN-to-cBN bonding in the samples had given rise to an improvement in cutting performance.

An extensive new solid solution was synthesized by substitution of Pd+2 for Cu+2 in Bi2CuO4 compound [J.-C. Boivin et al., C.R. Hebd. Seances Acad. Sci., Ser. C 276, 1105 (1973)]. Polycrystalline ceramic powder with formula Bi2Cu $_{1-x}$ Pdx O4 were prepared by sol-gel method using (Bi, Cu, Pd) nitrates and pure citric acid. X-ray patterns show a single phase with tetragonal symmetry and space group P4/ncc (No. 130). In cases, the tetragonal cell c parameter and therefore the metal-metal distance (d M-M = c/2) increases linearly with increasing palladium concentration. Electrical conductivity measurements show that the resistivity decreases regularly with pd2+ substitution. It is possible to obtain materials with an ambient temperature conductivity ranging from 10-6 to 10-3 S cm-1.