Three-dimensional crystalline Si films were grown by the Ni silicide mediation. The metal-induced growth method, which is a spontaneous reaction of metal and silicon, forms a silicide layer first then induces the crystalline Si growth. By controlling the reaction between Ni and Si, the silicide formation was modulated. The NiSi2 migration crystallizes a Si film behind and mediates crystalline Si above it. The mechanism of silicide-mediated three-dimensional Si crystallization and the thin Si film Schottky photodiode are presented.