Quartz crucible inhomogeneities affect Czochralski silicon process

OH group mapping showed a 26.7 ppm variation between the top and bottom of crucibles, indicating non-uniformity in ingot production. (Image Source: ScienceDirect)

Researchers from Norway and Germany have published their research on the impact of impurities in fused quartz crucibles used in silicon PV ingot production. With the growing demand for monocrystalline silicon solar cells, there is rising interest in more robust fused quartz crucibles used in the Czochralski process. According to the researchers, the study focused on the uniformity of hydroxyl (OH) impurities and their potential effect on crucible viscosity. Using infrared microscopy and a custom viscosity measurement setup, they mapped OH content in crucibles made from different sands. The findings revealed local variations of up to 26.7 ppm between the top and bottom. However, no direct correlation was observed between the OH content and viscosity in the research. The researchers have attributed these inhomogeneities to differences in sand quality, particle size, and manufacturing processes.