Cross sectional transmission electron microscopy (TEM) reveals an amorphous interfacial region of the order of 2 nm thick between chemical vapor deposition-(CVD) deposited polycrystalline silicon films and the single-crystal silicon substrate. The continuity of this region varies from sample to sample and plays an important role in the effects produced by subsequent heat treatment. In cases where this interfacial layer is continuous, the deposited layer remains polycrystalline. When the region is discontinuous, complete epitaxial realignment of the poly is possible. The speed of realignment depends on the implanted arsenic dose and is much greater than reported for undoped films. Various impurities are also observed at the interface and correlate with the character of the interface.