We have explored various gas phase processes for the fabrication of nanometersized Si and SiO x particles and measured their structural properties (agglomeration, size, shape, crystallinity, surface roughness and internal structure) by conventional and high resolution electron microscopy. Agglomerated amorphous Si particles, 10±30 nm in size, were prepared by gas phase reactions including cluster growth processes in a low pressure silane plasma. Annealing at 900°C resulted in almost complete crystallisation of nearly spherical particles covered by an amorphous oxide shell. Inert gas arc evaporation of silicon yielded single crystalline, spherical Si particles, 4±16 nm in size, in which no defects were detected. 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 agglomerated, nearly spherical amorphous SiO x particles, 8±24 nm in size, with considerable surface roughness. Upon annealing at 900°C, the formation of 3±6 nm sized Si crystallites in the interior of these particles was observed. Ó

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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 4‐16 nm 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 at 900°C the formation of 3‐6 nm sized Si crystallites in the interiro of these particles were observed.