A SOLAR CELL AND FABRICATION METHOD USING CRYSTALLINE SILICON BASED ON LOWER GRADE FEEDSTOCK MATERIALS

摘要

Formation of a solar cell device from upgraded metallurgical grade silicon which has received at least one defect engineering process and including a low contact resistance electrical path. An anti- reflective coating is formed on an emitter layer and back contacts are formed on a back surface of the bulk silicon substrate. This photovoltaic device may be fired to form back surface field temperatures sufficiently low to avoid reversal of previous defect engineering processes. The process further forms openings in the anti-reflective coating and a low contact resistance metal layer, such as nickel layer, over the openings in the coating. The process may anneal the low contact resistance metal layer to form n- doped portion and complete an electrically conduct path to the n-doped layer. This low temperature metallization (e.g., < 700°C) supports the use of UMG silicon for the solar device formation without risk of reversing earlier defect engineering processes.