Heteroepitaxy of insulator/metal/silicon structures: CaF2/NiSi2/Si(111) and CaF2/CoSi2/Si(111)

Abstract

Epitaxial insulator (CaF2) layers have been grown on epitaxial metal (CoSi2 and 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 CaF2 using 2.5 MeV 4He+ ions. CaF2 layers grown at 650 °C on CoSi2 consist of a mixture of regions either aligned or rotated 180° with respect to the CoSi2 lattice, while CaF2 layers grown at 550 °C on NiSi2 are of a single orientation, regardless of the orientation of the NiSi2 with respect to the Si substrate.