Characterization of Defects in Single Crystal Epitaxial Silicon for Solar cells.

摘要

In semiconductor technology for solar applications, the demand for high level of structural perfection in single crystal silicon has increased. The defects in the crystals can affect the efficiency of solar cells, so the study of imperfections is important for providing feedback to develop high quality crystal. X-ray topography is a nondestructive method and a powerful tool to evaluate crystals for technological applications, growth and processing.;In this study, defects in homoepitaxial silicon epilayers grown by chemical vapor deposition (CVD) for solar cell application with the dislocation density of 9.4x103cm-2 have been mapped and characterized by synchrotron white beam X-ray topography (SWBXT), synchrotron monochromated beam X-ray topography, high resolution X-ray diffraction and optical microscopy. In free standing 200microm thick epitaxial single crystal silicon detached from the silicon substrate, a crisscross network of screw dislocations, misfit dislocations and multiple stacking fault configurations are revealed and quantitatively characterized. The silicon epitaxial layer (~60microm) attached to the silicon substrate is characterized by threading dislocations, misfit dislocations and a non-uniform distribution of bending stains from mismatch. These defects can impact the performance and yield of this CVD process for solar cell manufacturing.