Evaporated Si grew epitaxially on Si(I 0 0) at approximately 500 degreesC when very thin Ni layers were deposited on the substrate even under a medium vacuum condition of 10(-7) torr. Cross-sectional TEM and electron diffraction showed the formation of a thin and uniform epitaxial NiSi2 layer on the Si substrate. Thus the Ni enhanced low-temperature Si epitaxial growth can be explained by a Si/NiSi2/Si hetero-epitaxial model. Agglomerated NiSi, particles were also observed in the NiSi, layer, and the density increased with increasing deposited Ni layer thickness. Lattice defects were generated in the Si epitaxial layer from the agglomerated NiSi, Thus, the thinner the Ni deposited layer, the better the crystallinity of the Si epiaxial layer obtained.