Distribution and propagation of dislocation defects in quasi-single crystalline silicon ingots cast by the directional solidification method

We investigated the distribution and propagation of dislocation defects in quasi-single crystalline (QSC) silicon ingots. The dislocation distributions in both the central single crystalline region and the surrounding polycrystalline region of the ingot are measured and compared. Although the dislocation density in the central single crystalline region is much lower than that in the surrounding polycrystalline region, dislocations in this region propagate and spread with the growth of the silicon crystal, especially at the final stage of solidification. The performances of solar cells made of wafers from different parts of the QSC silicon ingot are also compared. The results show that solar cells made of wafers from the middle part of the ingot have the best performance and those made of wafers from the top part of the ingot have the worst performance.