STRUCTURE OF NANOMETERSIZED SILICON PARTICLES PREPARED BY VARIOUS GAS-PHASE PROCESSES

We have explored various gas phase processes for the fabrication of na nometersized Si and SiOx particles and measured their structural prope rties (agglomeration, size, shape, crystallinity, surface roughness an d internal structure) by conventional and high resolution electron mic roscopy. Agglomerated amorphous Si particles, 10-30 nm in size, were p repared by gas phase reactions including cluster growth processes in a low pressure silane plasma. Annealing at 900 degrees C resulted in al most complete crystallisation of nearly spherical particles covered by an amorphous oxide shell. Inert gas are evaporation of silicon yielde d single crystalline, spherical Si particles. 4-16 nm in size, in whic h no defects were detected. These particles, agglomerated into chains and tangles, are covered entirely by a thin amorphous oxide layer. The rmal evaporation of solid SiO in an inert gas atmosphere produced aggl omerated, nearly spherical amorphous SiO, particles, 8-24 nm in size, with considerable surface roughness. Upon annealing at 900 degrees C t he formation of 3-6 nm sized Si crystallites in the interior of these particles was observed. (C) 1995 Elsevier Science B.V. All rights rese rved.