Microscopic defects and impurity analyses of multicrystalline silicon solar cells from different manufacturing routes

It is important to fully understand the physical behavior of solar cells made by materials from alternative process routes. Solar cells from Elkem Solar Grade Silicon and standard polysilicon have been investigated with light beam induced current and electroluminescence imaging. The low efficiency regions have been further analyzed by Scanning Electron Microscopy under different imaging modes. It was found that cell regions of low performance had undergone plastic deformations resulting in the creation of crystalline defects appearing as subgrain patterns. Similar patterns were observed in both ESS™ and standard polysilicon. Energy-dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) were used to study crystallographic orientations and impurities.