Epitaxial growth of iridium and platinum films on sapphire by metalorganic chemical vapor deposition

Ir and Pt epitaxial films were grown on (0001), (112̄0), and (011̄2) sapphire by metalorganic chemical vapor deposition using Ir- or Pt-acetylacetonate precursors. The epitaxial growth was achieved at deposition temperatures between 500 and 600 °C with the addition of oxygen to the source vapor. The film orientation and epitaxial relationships between films and substrates were determined by x-ray diffraction, x-ray pole figures, and reflection high energy electron diffraction. Ir films on (112̄0) sapphire grow in [100] orientation. Ir or Pt films on (011̄2) and (0001) sapphire grow in [111] orientation. Ir films on (0001) sapphire contain two in-plane orientations related by a 180° rotation, while Pt films containing only one in-plane orientation can be obtained on (011̄2) and (0001) sapphire.