Large-grain polysilicon seed layers on glass for epitaxial silicon solar cells

Thin-film silicon solar cells remain a promising technology to approach wafer-based efficiencies at thin-film costs. Epitaxial growth of silicon cells on seed layers has been a prominent approach with demonstrated efficiencies. However, cost-effective seed layers on glass or other low-cost substrates still remain one of the biggest road blocks to the success of this technology. Top-down aluminum induced crystallization (TAIC) has been developed to produce large-grain silicon seed layers on glass. Initial cells have been fabricated by Hot-Wire CVD at the National Renewable Energy Laboratory (NREL). The seed layers with grain-gaps show poor electrical characteristics comparable to reported cells grown on wafer templates with defect densities around 2 × 106 cm-3. New seed layers without grain gaps have been developed and are in queue for cell fabrication.