Synthesis and structural characterisation of Si and SiOx particles of nanometer sizes

The possibilities of various gas phase processes for fabrication of nanosized Si and SiOx particles have been explored in a comparative study. Conventional and high resolution electron microscopy was used to investigate in detail agglomeration, size, shape, crystallinity, surface roughness and internal structure of the particles, respectively. Accretions of nearly spherical crystalline Si particles of 2-8 nm size mostly embedded in amorphous matrix were prepared by means of a gas evaporation cluster source. Their structural characteristics depend on the aggregation conditions applied. Inert gas are evaporation of silicon yielded single crystalline, spherical Si particles 4-16nm in size being completely free of defects. These particles, agglomerated into chains and tangles, are covered entirely by a thin amorphous oxide layer. Thermal evaporation of solid SiO in an inert gas atmosphere produced highly agglomerated, nearly spherical amorphous SiOx particles 8-24 nm in size with a considerable surface roughness. Upon annealing al 900 degrees C the formation of 3-6 nm sized Si crystallites in the interior of these particles were observed.