ZnSe ionicity control layer inserted in GaAs/CaF,(l 11) interface

For heteroepitaxial growth of covalent crystals on ionic crystals which have very different ionicities, we propose a new approach of introducing a material which has intermediate ionicity to the heterointerface for the purpose of accommodation of the large ionicity difference. By introduction of a thin ZnSe layer to the interface of GaAs/CaF,( 111) as a buffer layer, we successfully improved the crystallinity of the MBE-grown GaAs layer, which was examined by the double crystal X-ray diffraction method. The ZnSe layer was grown by a 2-step growth method in which a few nm ZnSe was deposited at low temperature on an epitaxial CaE, film grown on Si(ll1) substrate and it was annealed in situ before overgrowth of GaAs. The growth conditions of the ZnSe layer such as deposition temperature, thickness, and annealing temperature were studied to obtain good crystallinity of the GaAs overlayer.