Control of crystal orientations in lattice-mismatched srf₂and (Ca, sr)f₂films on si substrates by intermediate caf₂films

Crystal orientations of SrF₂and (Ca, Sr)F₂films on Si. 100) and. 111) substrates were controlled by intermediate CaF₂films which were grown on the substrates prior to growth of lattice-mismatched fluoride films. SrF₂films with good crystalline quality were grown epitaxially on the CaF₂/Si. 100) structure, though the SrF₂films directly grown on Si. 100) were mainly composed of preferentially. 111) oriented crystallites. Similarly, (Ca, Sr)F₂films on Si. 111) changed from epitaxial films with internal boundaries between regular and rotationally twinned crystallites to single crystal ones by use of the intermediate CaF₂films.