Nanostructured Au films were deposited on Si(111) by room-temperature sputtering. By the atomic force microscopy technique we studied the evolution of the Au film morphology as a function of the film thickness h and annealing time t at 873 K. By the study of the evolution of the mean vertical and horizontal sizes of the islands forming the film and of their fraction of covered area as a function of h from 1.7×1017 to 1.0×1018 Au/cm2 we identified four different growth stages such as: (1) 1.7×1017≤h≤3.0×1017 Au/cm2, nucleation of nanometric three-dimensional (3D) hemispherical Au clusters; (2) 3.0×1017<h≤5.2×1017 Au/cm2, lateral growth of the Au clusters; (3) 5.2×1017<h≤7.7×1017 Au/cm2, coalescence of the Au clusters; (4) 7.7×1017<h≤1.0×1018 Au/cm2, vertical growth of the coalesced Au clusters. The application of the dynamic scaling theory of growing interfaces allowed us to calculate the dynamic scaling exponent z=3.8±0.3, the dynamic growth exponent β=0.38±0.03, the roughness exponent α=1.4±0.1 and the Avrami exponent m=0.79±0.02. Finally, the study of the evolution of the mean Au clusters size as a function of annealing time at 873 K allowed us to identify the thermal-induced self-organization mechanism in a surface diffusion limited ripening of 3D structures and also the surface diffusion coefficient of Au on Si(111) at 873 K was estimated in (8.2×10−16)±(3×10−17) m2/s.

Very thin Au layers were deposited on SiC hexagonal and SiO2 substrates by sputtering. The Au surface diffusion, clustering, and self-organization of Au nanoclusters on these substrates, induced by thermal processes, were investigated by Rutherford backscattering spectrometry, atomic force microscopy, scanning electron microscopy, and transmission electron microscopy. On both types of substrates, clustering is shown to be a ripening process of three-dimensional structures controlled by surface diffusion and the application of the ripening theory allowed us to derive the surface diffusion coefficient and all other parameters necessary to describe the entire process. The system Au nanoclusters/SiC and Au nanoclusters/SiO2 are proposed as nanostructured materials for nanoelectronic and nanotechnology applications.

The morphology evolution of nano-grained Ag and Au films deposited on polystyrene (PS) and poly(methyl methacrylate) (PMMA) polymeric layers were studied, using the atomic force microscopy technique, when annealed above the polymers glass transition temperature. The main effects on the morphology changes were identified with those concerning the embedding kinetics of the Ag and Au nanoparticles in the PS or PMMA layers. The embedding process of the nanoparticles follows as a consequence of the long-range mobility of the polymeric chains above the glass transition temperature. In particular, the dependence of the nanoparticles mean height and surface density on the annealing time at various temperatures was quantified. The analyses of these behaviors allowed us: (1) to distinguish the overall embedding process in a first stage in which a thin wetting layer of the polymer coats the nanoparticles followed by a true embedding process of the nanoparticles into the polymer layer; (2) to evaluate the characteristic coating time for the Ag and Au nanoparticles in the PS and PMMA in the first stage; (3) to evaluate the characteristic embedding velocity for the Ag and Au nanoparticles in the PS and PMMA in the second stage; (4) to derive the activation energies for the embedding process of the Ag and Au nanoparticles in PS F. Ruffino ( ) · M.G. Grimaldi

Experiments are reported for Te and Ag implantation in silicon, as examples of slow and fast diffusers, after furnace or laser annealing. Slow diffusers are substitutionally located at concentrations in great excess of the maximum solid solubility after both processes. Fast diffusers inhibit the solid-phase epitaxial regrowth or are rejected at the sample surface after laser irradiation. Although the epitaxial growth occurs with velocities which differ up to ten orders of magnitude after furnace or laser annealing, the supersaturation is interpreted as due to the same basic mechanism: solute trapping at the moving interface when the residence time is larger than the one monolayer regrowth time. This process is controlled by the diffusion coefficient in the two adjacent phases.