Ti/MgO superlattices epitaxially grown on sapphire (00.1) and MgO(001) substrates

Epitaxial metal/insulator superlattices composed of Ti and MgO have been prepared on MgO(001) buffer layers grown on MgO(001) substrates and MgO(111) buffer layers grown on sapphire (00.1) substrates by electron beam evaporation in ultrahigh vacuum. 1-4-nm-thick Ti layers and 1-2-nm-thick MgO layers have been grown alternatively for 20 periods on the buffer layers at 273 K and at a growth rate below 0.02 nm/s. The reflection high energy electron diffraction and x-ray diffraction measurements reveal that the crystal structures of Ti in the superlattices grown on MgO(001) and on sapphire (00.1) substrates are face-centered tetragonal structure and hexagonal closed-packed structure, respectively. (C) 1996 American Institute of Physics.