ZNSE IONICITY CONTROL LAYER INSERTED IN GAAS CAF2(111) INTERFACE/

For heteroepitaxial growth of covalent crystals on ionic crystals whic h have very different ionicities, we propose a new approach of introdu cing 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/CaF2(111) as a buffer layer, we successfully improved the crystallinity of the M BE-grown GaAs layer, which was examined by the double crystal X-ray di ffraction method. The ZnSe layer was grown by a 2-step growth method i n which a few nm ZnSe was deposited at low temperature on an epitaxial CaF2 film grown on Si(111) substrate and it was annealed in situ befo re overgrowth of GaAs. The growth conditions of the ZnSe layer such as deposition temperature, thickness, and annealing temperature were stu died to obtain good crystallinity of the GaAs overlayer.