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The use of multi-crystalline silicon for photovoltaic solar cell applications is highly advantageous due to its low manufacturing costs. In this study, numerical simulations were conducted to investigate mass transport phenomena during the directional solidification of molten silicon for different Schmidt values at the critical Prandtl number of 0.01. The simulations were performed using the diffusion model and convection-conduction equations as the framework for the incompressible Navier-Stokes equation. The finite-volume method was used to carry out computations in a two-dimensional (2D) axisymmetric model. The diffusion flux of impurities (oxygen, carbon, and nitrogen) and dopants (phosphorus and boron) during the mc-silicon growth process was examined for Schmidt numbers Sc=0.5, Sc=5, and Sc=10. It was found that the Schmidt number Sc=0.5 is suitable for producing higher-grade mc-silicon ingots by regulating the production of impurities and dopants. The simulation results obtained in this study may provide a better understanding of the mc-silicon growth process and can be used to improve the production of high-quality mc-silicon ingots for photovoltaic applications.

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.