Growth of Single‐Crystalline Epitaxial Group II Fluoride Films on InP ( 001 ) by Molecular‐Beam Epitaxy

Abstract

Twin‐free, single‐crystalline, lattice‐mismatched as well as lattice‐matched, epitaxial dielectric films of group II cubic fluorides (, , and ) have been grown on substrates by molecular‐beam epitaxy. The surface was cleaned in vacuum by heating under phosphorus overpressure until a well‐ordered and stoichiometric surface was obtained. The film growth of ,where M is Ba, Sr, Ca, or , was followed by reflection high energy electron diffraction (RHEED). The diffraction patterns indicate a parallel epitaxial relationship: and. At low growth temperature (∼250°C) and low growth rate we could obtain twin‐free single‐crystalline films. Transmission electron microscopy show the absence of any grains. At higher growth temperature (∼350°C) we could obtain twin‐free single‐crystalline , , and films. The latter can be lattice‐matched to at room temperature.