An optical microscopy study of dislocations in multicrystalline silicon grown by directional solidification method

With the growing market shares for directionally solidified multicrystalline silicon (mc-Si) based solar cells in recent years, it is of practical interest to investigate crystal defects present in the mc-Si materials. Dislocation is the primary crystal defect in mc-Si, and it plays an important role in influencing the photovoltaic properties of mc-Si solar cells. In this work, we employed optical microscopy to investigate dislocations in mc-Si grown by the industrial directional solidification method. It was found that the distribution of dislocations in mc-Si is highly inhomogeneous from one grain to another. High inhomogeneity in dislocation distribution was also observed in individual grains. A large number of slip dislocations were generally observed in mc-Si. The origin of dislocations, the distribution inhomogeneity of dislocations, and their effects on the photovoltaic properties of mc-Si solar cells were discussed.