Residual Thermal Stresses Simulation for Multi-crystalline Silicon Casting

Multi-crystalline silicon is the major material used for solar cells due to its low production costs and high conversion efficiency. When melting silicon transforms from the liquid phase to the solid phase, dislocations are generated by the temperature gradient and thermal stresses. The disloactions become recombination centers for minority charge carries, decreasing conversion efficiency. Since verifying the change of stress of a silicon ingot is difficult during solidification, computer simulations are used to optimize the parameters of the multi-crystalline silicon ingot casting process. In this study, a numerical model of a silicon ingot is developed to carry out residual thermal stress simulations. The result obtained under various control conditions are dicussed.