Gedanken experiment on point defects in unidirectional solidified single crystalline silicon with no dislocations

A gedanken experiment was carried out to investigate point defects formed in unidirectional solidified single crystalline silicon for solar cells, ignoring dislocations in crystals. A transient global model was used to obtain the solution of a thermal field within the entire furnace. Then, based on the global solution of heat transfer, diffusion and recombination of vacancies and interstitials were calculated by the Finite Volume Method (FVM). It was found that vacancies became dominant as the melt was solidified and solidification time was reduced. The ratio between growth rate V_g and temperature gradient in growth direction G was also analyzed. The results revealed that growth rate is the key factor affecting point defects in single crystalline silicon with no dislocations.