Fabrication of semiconducting SrB6−δ thin films on ultrasmooth sapphire substrates by laser molecular beam epitaxy

We fabricated epitaxial SrB6 (1 0 0) thin films on ultrasmooth sapphire (α-Al2O3 single crystal) (0 0 0 1) substrates by laser molecular beam epitaxy. Reflection high-energy electron diffraction and X-ray diffraction measurements indicated the heteroepitaxial structure of SrB6 (1 0 0)/sapphire (0 0 0 1) with three domains of epitaxial relationship. The prepared films exhibited atomically stepwise surface morphology, similar to that of the ultrasmooth substrate used, with 0.2-nm-high atomic steps and ∼70-nm-wide terraces. The SrB6 epitaxial thin films showed semiconducting behavior, with a resistivity of 4.8 Ω cm at room temperature.