The scaling of complementary metal oxide semiconductor (CMOS) transistors has led to the silicon dioxide layer used as a gate dielectric becoming so thin (1.4 nm) that its leakage current is too large. It is necessary to replace the SiO2 with a physically thicker layer of oxides of higher dielectric constant (κ) or ‘high K’ gate oxides such as hafnium oxide and hafnium silicate. Little was known about such oxides, and it was soon found that in many respects they have inferior electronic properties to SiO2, such as a tendency to crystallise and a high concentration of electronic defects. Intensive research is underway to develop these oxides into new high quality electronic materials. This review covers the choice of oxides, their structural and metallurgical behaviour, atomic diffusion, their deposition, interface structure and reactions, their electronic structure, bonding, band offsets, mobility degradation, flat band voltage shifts and electronic defects. The use of high K oxides in capacitors of dynamic random access memories is also covered.

Non-ablative laser heating has recently turned out to be an efficient synthesis method for boron nitride (BN) nanotubes, offering flexibility in the control of experimental parameters. Long tubes are obtained as a hairy growth on the target around laser impact. Tubes are mostly assembled in bundles and thin. Selected area diffraction diagrams reveal that zigzag and armchair helicities are dominant, without preference. A field emission gun enabled to resolve the fine modulations in the diffraction diagrams for multi-walled nanotubes (MWNT) and for bundles of MWNT. The interpretation of the diffraction pattern of nanotubes is generalised for such modulations, considering the analytical expression of the diffracted amplitude at each graphite reflection. The fine modulations in the pattern are linked to roll diameters, bundle lattice, and interlayer distances. Experimentally, several roll diameter modulations are observed. Unusual modulations corresponding to an interlayer distance of 2 layers are also observed. They show a two-roll period, with an alternative shift along tube axis, in the piling of the rolls of MWNT.

Multiwalled carbon nanotubes (MWNTs) were displaced on low-friction graphite surfaces in an easily controlled fashion by moving a voltage-applied tip of an atomic force microscope (AFM) across them. MWNTs on Si (5 5 12) surfaces were not displaced using the same electrostatic parameters. The friction at a Si (5 5 12) surface was measured to be 29 times larger than that of a graphite surface. We found that the electrostatic force applied to the MWNT was larger than the frictional force between the MWNT and the graphite surface, but much smaller than the frictional force on the Si (5 5 12) surface, allowing us to conclude that the electrostatic force may be responsible for the displacement of the MWNT on the graphite surface.

In this paper we report a study of the magnetostatic coupling of square dot films and strips of films of Permalloy/Copper/Permalloy (200/20/200 nm). Results show a good magnetostatic coupling which leads to a monodomain structure in the case of square dots as it is observed from hysteresis loops. These monodomain structures appear to be stable for a wider range of dot dimensions rather than in monolayers. Magnetic simulations also support the existence of these kind of magnetic structures. Results obtained for strips are also reported. These samples exhibit a multidomain structure where it is possible to observe a coupling between domains and also between domain walls in the different magnetic layers.

Distinction between superhard coatings obtained by energetic ion bombardment during their deposition and superhard nanocomposites whose superhardness and high thermal and oxidation stability originates from a stable nanostructure is described together with the properties of the latter materials. The reasons for the poor reproducibility of our data as reported by some authors may be either an incorrect choice of a too low nitrogen pressure or temperature during the deposition or built-in impurities, or a combination of those.

Removal of molecular atmospheric pollutants by non-thermal plasmas is under study since the beginning of the eighties. It has been shown that pulsed electrical discharges, such as dielectric barrier or corona discharges, are powerful means to eliminate Volatile Organic Compounds (VOCs) from the ambient air, or to treat flue gases which contain nitrogen oxide. However it is now recognised that, for several pollutants, the use of the plasma alone does not allow a complete elimination of the undesirable molecule. For example NO is oxidised in the air plasma to form other oxides like NO2 and N2O5, and reactions of oxygen atoms or hydroxyl radicals produced by the discharge with VOCs can lead not only to H2O and CO2 but to a number of by-products following the partial oxidation of the molecule, which can be as undesirable than the compound to be initially removed from effluents. This is particularly the case when the electrical energy deposited in the gas flow must be kept as low as possible in order to design a low energy cost equipment. As a result addition of a catalyst together with the pulsed discharge is now investigated in various laboratories in order to achieve a complete oxidation of VOCs, i.e. the so-called de-COV process, or a complete reduction of NOX (NO and NO$_{2})$ to produce N2 and O2, i.e. the so-called de-NOX process, at low energy consumption. This paper is a short review of works which have been done these last years in that domain, specifically on NOX and some selected VOC molecules.

Metastable atoms play an important role in the kinetics of plasmas. A self-absorbing method has been used to determine the population density of Ar(3P0) and Ar(3P2) atomic metastable levels and Ar(1P1) and Ar(3P1) atomic resonant levels in an argon microwave discharge sustained by a surface wave at atmospheric pressure. Under the operative conditions investigated, the concentrations of these levels ranged from 1010−1012 cm−3, being in agreement with those reported in the literature, which seems to indicate that this method could be used for this calculation.

Low dielectric constant materials (low-k) are used as interlevel dielectrics in integrated circuits. This paper concerns the etching process of these materials in high density plasma with the aim to provide some insights concerning the etch mechanisms. Materials studied are methylsilsesquioxane (MSQ) polymers, either dense (SiOC) or containing 40% of porosity (porous SiOC). Amorphous hydrogenated silicon carbide (SiC) material, used as hard mask and/or etch stop layer, is also investigated. Etch is performed in an inductively coupled reactor using fluorocarbon gases, which have proven to be very successful in the etch of conventional SiO2. First, etching with hexafluoroethane (C2F$_{6})$ is performed. Although etch rates are high, etch selectivities with respect to SiC are weak. So, oxygen, argon, and hydrogen are added to C2F6 with the aim of improving selectivities. The best selectivity is obtained for the C2F6/H2 (10%–90%) mixture. To understand etch rate and selectivity variations, plasma analyses by optical emission spectroscopy are correlated to surface analysis using X-Ray Photoelectron Spectroscopy (XPS). In general, atomic fluorine concentration in the plasma explains the etch rate, while the presence of a fluorocarbon layer on the surface is well correlated to the selectivity. To ensure that the etch process does not affect materials properties, and particularly their dielectric constant, bulk analysis by Fourier Transformed Infra-Red spectroscopy and images by Scanning Electron Microscopy have also been carried out.

In previously published papers [G. Musa et al., Rom. Rep. Phys. 49, 195 (1997); G. Musa et al., Eur. Phys. J. Appl. Phys. 4, 165 (1998)] we reported a drastic change of time evolution of the barrier discharge current at the addition of hydrogen to neon–filling gas of the discharge device. Both, discharge current and discharge emitted light durations increase at least five times. We established that the main explanation of the above mentioned behavior consists in the negative-positive ion recombination, process which has one of the largest known cross–section [M.A. Lieberman and A.J. Lichtenberg, Principles of plasma discharges and material processing (John Wiley & Sons, N.Y., 1994)]. The first condition to have negative-positive ions recombination is to use as filling gas of the discharge device an electronegative–electropositive gas mixture [G. Musa et al., ESCAMPIG-16, Grenoble France, 2002, Vol. 2, p. 29; G. Musa et al., J. Phys. D: Appl. Phys. 18, 2119 (1985); A. Baltog et al., Contrib. Plasma Phys. 40, 537 (2000); G. Musa and A. Baltog, Contrib. Plasma Phys. 43, 210 (2003)]. Additional conditions must be fulfilled in order to ensure enough density of negative ions necessary for such a recombination process. An increased “consumption” of electrons is necessary to produce needed negative ions. Consequently, the wall polarization process is slowing down with subsequent increase of the light emission and discharge current duration. Possible use of this increase of light emission at electronegative gas addition to the filling gas neon as a mean to increase the discharge light generation efficiency is considered.

A range of silicon-based optical thin films have been deposited in a matrix distributed electron cyclotron resonance (MDECR) reactor. Process parameters were optimized in order to obtain optical quality thin films at low substrate temperatures and high deposition rates without post-deposition treatment. Stoichiometric silica films have been deposited at the rates up to 70 nm/min at temperatures lower than 150 °C. Oxynitride films with a controllable refractive index ranging from 1.46 to 1.86 have been obtained from SiH4/O2/N2 mixtures. Real time process control by multichannel ellipsometry has been implemented and successfully applied for the deposition of silica, silicon oxynitrides and amorphous silicon. Better than 0.3% in thickness accuracy was achieved in high rate deposition of silica layers of various predefined thickness. Refractive indices were determined in real-time with an absolute precision of 0.005–0.02. The control algorithm was used for fabrication of multilayer optical filters. The results show that the MDECR concept coupled with real-time process control by ellipsometry can be technology of choice for the deposition of interference coatings.

The experimental determination of the iron losses created in a localized zone of an electric machine is a difficult operation. We try to verify and to valid by local thermal measurements the sum of local iron losses. To realize our verification, we determine the optimal measurement conditions by calculation and simulation before the realization of a prototype specially designed for this operation. This structure represents a part of an electric machine, with emphasis on inhomogeneous flux distribution areas. This device permits to obtain an experimental temperature mapping which is compared to the calculated temperature distribution obtained by finite elements modelling.

A hybrid method is presented for the calculation of the interaction of a complicated shape ferrite-core eddy current testing probe with extremely small size cracks in a plate. The method is obtained by blending the boundary integral (BIM) and finite element (FEM) methods preserving their attractive properties, that is, the fast and accurate evaluation of the defect field and the versatility in specimen and probe geometry, respectively. FEM is applied for the computation of the electric field induced in the specimen without cracks. Using the obtained, so-called, incident field the BIM is used for the calculation of the field perturbation due to the presence of the cracks in the tested specimen. With the application of the presented hybrid calculations, a very fast and accurate method is developed for the solution of a problem that would pose considerable difficulties for either the FEM or the BIM if they were applied purely alone in the conventional way. The results of the calculations are compared with a large number of experimental data. The very good correlation between the measured and simulated probe responses proves the applicability of the presented method.

High-frequency ultrasonic pulses at 36 MHz are used to measure velocity profiles in a complex fluid sheared in the Couette geometry. Our technique is based on time-domain cross-correlation of ultrasonic speckle signals backscattered by the moving medium. Post-processing of acoustic data allows us to record a velocity profile in 0.02–2 s with a spatial resolution of 40 μm over 1 mm. After a careful calibration using a Newtonian suspension, the technique is applied to a sheared lyotropic lamellar phase seeded with polystyrene spheres of diameter 3–10 μm. Time-averaged velocity profiles reveal the existence of inhomogeneous flows, with both wall slip and shear bands, in the vicinity of a shear-induced “layering” transition. Slow transient regimes and/or temporal fluctuations can also be resolved and exhibit complex spatio-temporal flow behaviors with sometimes more than two shear bands.

We previously used the Pulsed Photoacoustic Spectroscopy to quantify sunscreen chromophore diffusion into human skin, and suggested a methodology to evaluate the time and the depth diffusion profile into human skin. In the present study we present the results obtained for the diffusion of an emulsion in human skin, which is used in the sunscreen compositions. This study shows, for the first time, a particular behaviour due to a chemical reaction inside the skin during the diffusion process. This result brings a particularly interesting technique through the PPAS spectroscopy, to evaluate in situ, the eventual chemical reactions that can occur during drug diffusion into human skin. Numerical simulation allows us to understand the impact of thermal, optical and geometrical parameters on the photoacoustic signal and thus the physics of the diffusion phenomenon. The present simulation shows clearly that the $t_{\max}$ values corresponding to the maximum of the photoacoustic signal magnitude, $\Delta P _{\max}$, decrease when the thickness, $\ell $, of the sample decrease. Conclusions about possibilities and limitations of the considered model are discussed.