Analysis of grain structures and impurity distribution in mc-silicon grown by directional solidification: Computational and experimental approach

The grain structures and grain boundary characteristics such as grain orientation and formation of Σ 3 grain boundaries have been analysed in the wafers sliced from central and peripheral bricks of the ingot grown by G1 (15 Kg) directional solidification process. The orientation of grains and grain boundary characteristics in the wafers sliced from different parts of the ingot have been investigated using EBSD analysis. Large number of grains with different orientation are observed at the bottom of the ingot and the grain size increases from bottom to top as the growth proceeds. The density of grain boundary decreases with respect to the growth direction of the ingot. Simulation analysis has been done to investigate the overall growth process and the distribution of two major impurities such as carbon and oxygen impurities in the ingot. Simulation results are compared with experimental results and the relation between formation of grain boundaries and impurity concentration within the ingot has been analysed.