SiO2 and Si etching in a CF4/O2/Ar plasma has been carried out in an electron cyclotron resonance etcher over a wide range of conditions. The etch rate has been compared with the ion energy flux to the wafer surface, JiEi, and the atomic fluorine density in the gas phase, nF. It is found that the etch rate can be divided into two regimes by a critical value of nF/(JiEi), the ratio of the atomic fluorine density to the ion energy flux. The critical value can be determined from a contour plot of the etch rate as a function of the ion energy flux and the atomic fluorine density. The critical value of nF/(JiEi) for Si is higher than that for SiO2. For nF/(JiEi) higher than the critical value, the SiO2 etch rate linearly increases with the ion energy flux, and the Si etch rate shows a nonlinear increase with the ion energy flux. For nF/(JiEi) lower than the critical value, both SiO2 and Si etch rates linearly increase with the atomic fluorine density.

Different techniques of grafting polymer chains to filler surfaces are often employed to compatibilise filler and polymer matrices. In this paper the influence of graft length and graft density on the state of dispersion, crystallisation and rheological properties of poly(ε-caprolactone) (PCL)/silica (SiO2) nanocomposites are reported. Grafted silica nanoparticles were prepared through polymerisation of PCL from the nanoparticle surface. Graft length was controlled by the reaction time, while the grafting density was controlled by the monomer-to-initiator ratio. Grafted nanoparticles were mixed with PCL of different molecular weights and the state of dispersion was assessed. Different matrix-to-graft molecular weight ratios resulted in different states of dispersion. Composites based on the higher molecular weight matrix exhibited small spherical agglomerates while the lower molecular weight matrix revealed more sheet-like microstructures. The state of dispersion was found to be relatively independent of graft length and density. Under quiescent conditions the grafts showed increased nucleation ability in the higher molecular weight PCL, while in the lower molecular weight matrix the effect was less pronounced. Rheological experiments showed an increase in viscosity with increased filler content, which was beneficial for the formation of oriented structures in shear-induced crystallisation.

An innovative power electronics half-bridge module concept exploiting 3D-design features was proposed to achieve low stray inductance and balanced current sharing, and thus module fast switching capability. In order to verify the switching performance of the concept, a 1.2 kV / 100 A full SiC module was designed using electromagnetic simulations and fabricated exploiting state-of-the-art but still conventional packaging technologies. Afterwards the module was tested and benchmarked to commercially available SiC modules. Performed tests confirmed fast switching capability of the proposed concept and showed more than 20 % lower switching losses compared to the benchmarked commercial modules.978-1-4799-8609-5/15/$31.00 ©2015 IEEE

The vibrational relaxation of CO2 at LiF(100) has been investigated by monitoring infrared fluorescence from vibrationally excited molecules under conditions where they are relaxed primarily by collisions with the solid surface. The relaxation probabilities are found to be 0.65±0.10 at room temperature and 0.35±0.10 at 450 K. In order to understand better the vibrational relaxation results, angular distributions of CO2 scattered from LiF(100) were measured with a molecular beam scattering apparatus. At slow incident beam velocities, the trapping probability of CO2 at LiF(100) is essentially unity. Thus, in the vibrational relaxation measurements, where the incident velocity is even slower than in the scattering experiments, vibrational relaxation is preceded by trapping. Possible mechanisms for relaxation are discussed. Excitation of phonons in the solid and transfer of energy to other degrees of freedom of the molecule (i.e., translation, rotation, and other vibrational modes) are both plausible relaxation channels.

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