Abstract
In this report, rapid solidification mechanism in spherical silicons has been analyzed by means of the images of SEM(Scanning Electrons Microscope), X-ray pole plots analysis, and the numerical simulations of cooling rate of spherical silicons. We have adopted a jet-splitting method to produce spherical silicons at ultra-high speed(some hundreds of spherical silicon per second). Molten silicon passing through capillary forms jet and the jet is split into droplets by the hydrodynamic instability. The resulting silicon droplets are rapidly cooled and solidified to be spherical silicons. Much of spherical silicons produced by above method were found to be composed of crystalline silicon by Raman spectroscopy. And they were categorized into some groups according to the surface morphology and the cross-sectional image of the bulk. We found that the morphology of spherical silicons can be controlled by some conditions during fabrication and we propose the simple model that the cooling rate of a spherical silicon determines the surface morphology and the structure of the bulk.
