Epitaxial growth on silicon and characterization of $MnF2$ and $ZnF2$ layers with metastable orthorhombic structure

The growth of $MnF2$ and $ZnF2$ layers on Si(001) and Si(111) substrates was studied by molecular-beam epitaxy. Calcium fluoride buffer layers with (001), (110), and (111) orientations were used to prevent chemical interaction of $MnF2$ and $ZnF2$ molecules with the Si substrate. The analysis of x-ray and reflection high-energy electron-diffraction (RHEED) patterns showed that $MnF2$ layers grow on all of these planes in the orthorhombic $α‐PbO2$-type crystal phase observed earlier only at high pressures and temperatures. Atomic force microscopy revealed a strong dependence of the surface morphology on the buffer orientation and growth temperature. The best-ordered $MnF2$ growth occurred at 500 °C on a $CaF2$ (110) buffer layer. The diffraction analysis enabled us to find the epitaxial relations at the $MnF2$∕$CaF2$ interface. A careful analysis of the RHEED patterns of the films grown on $CaF2(001)$ showed a similarity in the structure and growth modes between $MnF2$ and $ZnF2$ layers, with $ZnF2$ tending to form multiphase layers. These findings are in agreement with the x-ray diffraction measurements.