Epitaxial Growth of Metal(CoSi2)/Insulator(CaF2) Nanometer-Thick Layered Structure on Si(111)

Epitaxial growth of a metal(CoSi2)/insulator(CaF2) nanometer-thick layered structure on Si(111) was demonstrated. An epitaxial CoSi2 layer on CaF2 was obtained by the two-step growth technique, i.e., solid phase epitaxy with the epitaxial Si layer grown in the first step and Co deposited in the second step. This technique was shown to be effective in avoiding the Co agglomeration on the CaF2 layer observed in the co-evaporation of Si and Co. An epitaxial CaF2 layer was formed on CoSi2/CaF2 at low substrate temperature (450°C) with a partially ionized and accelerated CaF2 beam, to avoid Co agglomeration in the CoSi2/CaF2 underlayer as well. Obtained results showed a single-crystalline nature in reflection high-energy electron diffraction (RHEED) and transmission electron microscopy (TEM) observations.