Characterization of nanoscale atomic motion of Si in polycrystalline Cu layer.

Atomic migration of silicon through grain boundaries of a thin polycrystalline Cu film and island formation on the Cu surface were studied in the temperature range of 403-520 K. Samples used in these experiments was prepared on Si(111) wafers by room temperature magnetron sputtering and they consisted of amorphous Si layer (80 nm) and polycrystalline Cu layer (40 nm). The silicon layer served as the source layer of diffusion, while the copper surface was the accumulation surface. Detection of Si atoms on the accumulation surface after penetration through the Cu layer was made by low energy ion scattering spectroscopy and the grain boundary diffusion coefficient DGB was determined from the appearance time. The depth distribution of Si in the Cu film was analysed by secondary neutral mass spectroscopy. From this depth distribution, DGB was also determined. By scanning probe microscope and electron microscope measurements, it was experimentally detected that Si atoms on the Cu surface did not form a continuous layer. Instead, amorphous Si islands were formed at the accumulation surface with surface protrusions in their centres.

Depositing silver nanoparticles on/in a glass slide by the sonochemical method.

A glass substrate was coated with silver by ultrasound irradiation. The structure and morphology of the nanoparticles in the deposited film were characterized using methods such as XRD, TEM, HR TEM, HRSEM, AFM, TOF-SIMS and optical spectroscopy. It was demonstrated that nucleation and the ensuing growth of the nanoparticles occurs in solution and is influenced by the concentration of the precursor, temperature and time of sonication. TOF-SIMS measurements revealed that silver nanoparticles passed through the glass interface and diffused within the glass substrate up to ∼60 nm. An analysis of the thermal effects accompanying the sonochemical cavitation of micro-bubbles in the solution near the solid surfaces shows that the collision of nanoparticles can lead to their melting and coalescence. Sonochemical deposition takes place layer by layer, so that the completion of the deposition of each layer of nanoparticles is followed by the sintering of adjacent particles and the formation of a close-packed layer. Using PVP as a stabilizing agent, a monolayer coating of silver nanoparticles on the glass surface was obtained. The coated glass demonstrated antibacterial activity.

Light scattering from particles located under a rough dielectric layer.

A discussion is presented of the effect of roughness on the detectability of subsurface particles by means of the light-scattering method. We have studied the scattering of light by calibrated spheres located under a slightly rough dielectric surface both experimentally and theoretically. In our experiments, the scattering from slightly rough layers with nonresonant particles was dominated by the roughness, and the scattering diagram did not bear any discernible indications of the spheres. However, at resonance, the subsurface particles manifested themselves by an increase in the total scattered intensity and by well-pronounced maxima in the angular dependence of both the scattering diagram and the backscattered intensity. Theoretical calculations show that the angular positions of the maxima in the scattering diagram are essentially determined by the interference of fields scattered by the particles and by the surface, whereas the contribution of the multiple interparticle scattering is negligible. By contrast, the oscillations in the angular dependence of the backscattered intensity are due primarily to the scattering between neighboring spheres.