EPITAXIAL-GROWTH OF ALKALINE-EARTH FLUORIDE FILMS ON HF-TREATED SI AND (NH4)2SX-TREATED GAAS WITHOUT INSITU CLEANING

HF-treated Si and (NH4)2Sx-treated GaAs were used as substrates for epitaxial growth of CaF2 and BaF2 films without in situ cleaning. The fluoride layers grown on the chemical-treated substrates exhibit good crystalline quality and smooth surfaces. With fluorides on Si, minimum ion channeling yields are about 3%-5%, comparable with the best data reported in the literature using thermal etching or sputtering for substrate cleaning. CaF2 and BaF2 films grown on GaAs (100) exhibit the same (100)-lattice orientation as the underlying GaAs substrate and no misoriented crystallites are observed. Pole figure measurements on BaF2 show that the crystallites are in close registry with the principal axes of the GaAs.