Fabrication and characterization of epitaxial films of ionic materials

We have investigated hetero-epitaxial growth of alkali halides, the most typical ionic material, on various kinds of substrates. In the case of growth of alkali halide on foreign alkali halide, layer by layer growth with or without coherent interface and island growth are observed according to the misfit value. In constrast, the lattice matching condition works for the growth of alkali halide on GaAs and Si substrates. Alkali halides/GaAs or Si system provides several basic problems such as ionic/covalent interface. On the other hand, it provides flat and conductive alkali halide surfaces. We have used this surface as a substrate for growth of some organic materials. Thickness dependence of surface phonon polariton of LiBr thin film grown on Si has been investigated. These results might open a new field in research of ionic material surfaces, interfaces and thin films.