Growth Mechanism of Si Faceted Dendrites(<Special Issue>Square-shaped Si Crystals for Solar Cell use)

Abstract

Si-faceted dendrites have unique crystal structures. The surface of dendrites is bounded by {111} facet planes, at least two parallel {111} twin boundaries exist at the center of the dendrites, and the preferential growth directions are <112> or <110>. Moreover, the growth velocity of dendrites is larger than equiaxed crystal grains. Such features can be applied in technology for growing multicrystalline Si (mc-Si) ingots for solar cells. We succeeded in observing the growth processes of Si <112> and <110> faceted dendrites by using originally developed in situ observation system. The growth scheme for the growth shape of the <112> and <110> dendrites were established based on our experimental evidence. The theoretical <112> and <110> dendrite growth velocities were calculated on the basis of the growth model established by our studies.