HETEROEPITAXIAL GROWTH OF TiO2, VO2, AND TiO2/VO2 MULTILAYERS BY MOCVD

Titanium and vanadium dioxide systems were selected to study the MOCVD process for the growth of oxide epitaxial films. Single-crystal Ti02 and V02 films in single and multilayered configurations have been successfully grown on sapphire (a-Al203) single-crystal substrates. Seven distinct epitaxial orientation relationships between the films and the substrates were observed. Discussion on these epitaxial relationships based on the consideration of atomic arrangements of the materials is presented. From our experimental results, we concluded that single layer films (both Ti02 and V@) were grown by the nucleations of three-dimensional clusters. Quantum mechanical calculations of the electronic structures, charge distributions, and energetics of the free substrate surfaces were performed and some results are presented.