Relationship between dislocation density and contact angle of dendrite crystals in practical size silicon ingot

Abstract

We suggested the possibility to suppress dislocation generation by controlling the microstructure of dendrite crystals in practical size Si wafers grown by the floating cast method. With the floating cast method, the contact angle between adjacent dendrite crystals can be used as a structural parameter to define grain boundaries (GBs). We fabricated a practical size silicon ingot fully covered with dendrite crystals and investigated dislocation density near the GBs as a function of the contact angle. The dislocation density was found to decrease with decreasing contact angle. This result can be explained by differences in shear stress on {111} slip surface around the GBs, as supported by numerical calculations considering various structural parameters in multicrystalline Si. These results confirm our previous results with laboratory-scale ingots, and we believe this concept can be applied to commercial growth processes.