Characterization of epitaxial (Ca,Ba)F₂ films on Si(111) substrates

We have investigated epitaxial BaF2/CaF2 bilayers on Si(111) with ion channeling, grazing-incidence x-ray diffraction, and transmission electron microscopy. The BaF2 layer, which was grown on a thin intermediate CaF2 layer, showed a channeling minimum yield of 8% and a residual strain of 0.2%. Regions of BaF2 with a mosaic spread in orientation were observed but otherwise the epitaxial quality of the fluoride bilayer was found to be very good.