Present status and future prospects of electromagnetic casting for silicon solar cells

Abstract

The development research of electromagnetic casting (EMC) for silicon crystal manufacturing technology has been carried out for years with the purpose of providing low cost multicrystalline silicon substrate for solar cells. The EMC technology is a new concept, in which electromagnetic force is utilized to suspend molten metal without contact to crucible wall for melting and solidification of silicon material. The first fundamental research for casting was begun in 1987 with a small round cross-sectioned ingot of 5 cm diameter, and the ingot size was gradually expanded with a square cross-sectioned ingot shape. The research has been carried out for the development of casting technique with an ingot size of 22/spl times/22 cm/sup 2/ cross section, and the furnace construction for producing a 35/spl times/35 cm/sup 2/ cross sectioned ingot has begun. Solar cell conversion efficiencies using EMC ingot crystals are in the range of 13-14%, and the quality of EMC material reaches within that of conventional mold casting material. By the improvements of higher casting speed, higher material quality and larger ingot size of EMC technology, it is expected that a new casting technique for lower cost ingot production will be realized.