Crystal morphology of spherical silicon particles produced by jet-splitting method

The influence of processing conditions on the shape and crystallinity of spherical silicon particles (φ=1 mm) produced by jet-splitting method was investigated by means of scanning electron microscope (SEM) and optical microscope. Silicon particles produced by this method were categorized into three groups according to the surface morphology of silicon particles. The surface morphology can be controlled by cooling rate during solidification and this method can produce 1 mm diameter spherical silicon particles consisting of only 2–3 grains. The yield of particles consisting of 2–3 grains increased with reducing cooling rate of spherical silicon particles. In this study, the cooling rate was estimated to be 650–750 K/s by our numerical simulations based on heat balance equation of a spherical silicon droplet. In a jet-splitting method, it is clearly observed that the cooling level prior to solidification is affected by the cooling rate of molten silicon droplets.