Polycrystalline silicon (poly-Si) films 4.5 µm thick, formed on glass substrates by flash lamp annealing (FLA) of precursor amorphous Si (a-Si) films, show remarkably long minority carrier lifetimes of approximately 100 µs after post-furnace annealing under N2 ambient. Even after crystallization by FLA, there remain a large number of H atoms, on the order of 1021/cm3, which probably effectively act to passivate dangling bonds in the poly-Si films. A minority carrier diffusion length of approximately 60 µm, estimated using the lifetime value, indicates high feasibility of realizing thin-film solar cells using this material.