Large-grained polycrystalline silicon on glass for thin-film solar cells

Large-grained polycrystalline silicon (poly-Si) films were prepared on glass using the 'seed layer concept' which is based on the epitaxial thickening of large-grained seed layers. The aluminium-induced layer exchange (ALILE) process was used to form p + -type seed layers on glass. The seed layers feature a preferential (100) orientation of the grain surface. Epitaxial growth of the p-type absorber layers was carried out at temperatures § 600°C by either electron cyclotron resonance chemical vapour deposition (ECRCVD) or electron-beam evaporation. Secco etching was used to analyse extended defects in the films epitaxially grown on ideal substrates (Si wafers). Opposed to ECRCVD, films grown with electron-beam evaporation show no etch pits when deposited on Si(100) wafers. Post-deposition treatments (defect annealing and defect passivation) were used to improve the quality of the absorber layers. Thin-film solar cells were prepared on both Si(100) wafers (ideal seed layer) and seed layer covered glass substrates by the deposition of an n + -type a-Si:H emitter and a TCO layer. The best solar cell results were