CRYSTALLIZATION OF AMORPHOUS NANO-SIZED SILICON POWDERS

The crystallization phenomena of nano-sized silicon powders (similar t o 20 nm) prepared by Plasma induced reaction of silane were studied us ing in-situ heating in vacuum (<10(-8) Torr) in a high resolution tran smission electron microscope (HRTEM) and ex-situ annealing in forming gas monitored by X-ray diffraction (XRD). In-situ HRTEM measurements s uggest that the primary crystallization process passes through two dis tinct regions: the formation of nano-crystallites which is followed by a sintering step which results in an increase in crystallite sizes. F urther, from XRD spectra we interprete that smaller crystallites form these larger grains which are observed by TEM.