Crystal Growth of Spherical Si

Abstract

The spherical Si single crystal with 1mmφ has intensively attracted technological interests, since the cutting loss required for Si wafer fabrication can be reduced by 20% in terms of the solar cell application. The basic understanding of crystal growth of Si single crystal ingots cannot be applied directly to spherical single crystals because the critical issue to be controlled is not growth, as for ingots, but nucleation from the undercooled melt for spheres. However, the nucleation is difficult to be controlled externally. In this chapter, our novel approach to grow spherical single crystals is presented after a short review of the historical background for spherical solar cells.