Keywords:melt growth, crystal-melt interface, in situ observation
Multicrystalline Si (Mc-Si) ingots for solar cells are produced by a unidirectional solidification method. Usually, crystal defects such as grain boundaries, twin boundaries, subgrain boundaries, dislocations, and impurities are present in Mc-Si at high density and inhomogeneity. These crystal defects serve as a carrier capturing site, which is a factor that deteriorates the solar cell performance. Therefore, in order to improve the quality of Mc-Si, it is necessary to control the grain size, grain orientation and crystal defects during the unidirectional solidification process. In this presentation, we will explain how grain boundaries, which are defects peculiar to polycrystalline materials, affect various phenomena at the solid-liquid interface based on experimental results.