Epitaxial insulator (CaF2) layers have been grown on epitaxial metal (CoSi2and NiSi2) layers on Si(111) by molecular beam epitaxy. The surface morphology and bulk crystallinity are much better for growth on NiSi2, with scanning electron microscopy revealing only small triangular hillocks, and channeling minimum yields as low as 3% measured in the CaF2using 2.5 MeV4He+ions. CaF2layers grown at 650 °C on CoSi2consist of a mixture of regions either aligned or rotated 180° with respect to the CoSi2lattice, while CaF2layers grown at 550 °C on NiSi2are of a single orientation, regardless of the orientation of the NiSi2with respect to the Si substrate.