Solidification of silicon for electronic and solar applications

Abstract

Silicon is widely used for its semiconducting properties in electronic and photovoltaic devices. These applications require strict control of the structure and impurity levels. Silicon must, therefore, be solidified using processes that give a minimum of impurity contamination and microstructural defects, as well as a planar solidification front to avoid microsegregation. Czochralski growth, and to some extent float zone crystallization, are processes used to obtain defect-free single crystals for integrated circuits and advanced solar cell wafers, whereas the Bridgman process can be used for production of multicrystalline silicon for standard solar cells. Direct solar cell wafer solidification processes have also been developed and reached limited commercial use. The paper will review these silicon crystallization processes and discuss recent developments and trends.