Crystallization of amorphous Si nanoclusters in SiO(x) films using femtosecond laser pulse annealings.

The SiO(x) films of various stoichiometries deposited on Si substrates with the use of the co-sputtering from two separate Si and SiO2 targets were annealed by femtosecond laser pulses. Femtosecond laser treatments were applied for crystallization of amorphous silicon nanoclusters in the silicon-rich oxide films. The treatments were carried out with the use of Ti-Sapphire laser with wavelength 800 nm and pulse duration about 30 fs. Regimes of crystallization of amorphous Si nanoclusters in the initial films were found. Ablation thresholds for SiO(x) films of various stoichiometries were discovered. The effect of laser assisted formation of a-Si nanoclusters in the non-stoichiometric dielectric films with relatively low concentration of additional Si atoms was also observed. This approach is applicable for the creation of dielectric films with semiconductor nanoclusters on non-refractory substrates.

Investigation of multilayer silicon structures with buried iron silicide nanocrystallites: growth, structure, and properties.

The growth of nanosize islands of iron silicides on Si(100) substrates and epitaxial silicon overgrowth atop them have been studied by low energy electron diffraction and reflectance high energy electron diffraction methods. The near optimal formation conditions of iron silicide islands with high density and minimal sizes have been determined by using of atomic force microscopy. Multilayer (8-10) monolithic structures with buried iron silicide nanocrystallites have been grown after the definition of monocrystalline burying conditions of iron silicides nanocrystallites in silicon lattice. The structure of buried nanocrystallites has been studied in multilayer monolithic heterostructures by high resolution transmission electron microscopy. It was established that in multilayer samples the majority of nanocrystallites have beta-FeSi2 structure, but some of them have gamma-FeSi2 structure. It was observed an influence of additional annealing at 850 degrees C on the morphology and structure of nanocrystallites. By means of deep level transient spectroscopy data one and two trap levels have been observed in multilayer structures (without and with additional annealing, respectively). Photoluminescence spectra have been studied at 4.2 K and the causes of its absence from buried beta-FeSi, NC have been analyzed.