Abstract: A method of fabricating a poly-crystalline silicon thin film, and a method of fabricating a semiconductor device using the same, includes implanting predominantly neutralized ions into an amorphous silicon thin film formed on a substrate. The thin film may be annealed. Glass, silicon and other substrates, such as heat intolerant substrates, e.g., plastic, may be employed. Eximer laser annealing using relatively high energy densities may be employed. Thin film transistors and numerous other semiconductor devices may be formed using the poly-crystalline silicon thin film.