Random angle grain boundary formation and evolution dynamics during Si directional solidification

Abstract

The growth of multicrystalline silicon and the formation of a random angle grain boundary, as well as the dislocation generation and expansion is observed dynamically in situ, by Synchrotron X-ray imaging techniques. The focus is kept on a random angle grain boundary since its behavior is particularly important to better understand the HP mc-Si (High Performance Multi-crystalline Silicon) photovoltaic properties. Due to the process conditions and to the grain competition that occurs during the solidification, a facetted {111} /facetted {111} groove is formed by this random angle grain boundary at the solid/liquid interface. It is shown how the shape of the solid/liquid interface allows the change of the preferential {111} growth facet and affects the grain boundary propagation direction. In one of the groove configurations, the two adjacent {111}

Dynamic observation of dislocation evolution and interaction with twin boundaries in silicon crystal growth using in – situ synchrotron X-ray diffraction imaging

“…Diffraction images contain information about the level of crystal perfection/deformation and the lattice defect formation such as dislocations and GBs [ 25 , 26 ]. Further information regarding the installation and previously obtained results can be found elsewhere [27][28][29][30] . Prior to the present experiments, the imaging system was upgraded to implement an indirect detector (scintillator coupled with a CMOS camera), replacing the traditional X-ray sensitive films, to record the Bragg diffraction images ( Fig.…”