Structural and morphological characterization of iridium coatings grown by MOCVD

The deposition of iridium coatings by MOCVD from iridium tris-acetylacetonate without gas reactant is reported. The effects of sublimation temperature of iridium tris-acetylacetonate precursor and types of substrates on iridium coating microstructure and morphology have been investigated at temperatures of 210 and 185°C on ceramic quartz and metal niobium substrates. X-ray diffraction analysis shows that the iridium coatings are polycrystalline phase. Scanning electron microscopy indicates that the iridium coatings have a two-layer structural characterization. Both the primary iridium layers on ceramic quartz and metal niobium substrates consist of chaotically oriented close-spaced spherical crystals of about dozens of nanometer and the second layer is ideally dense and compact coatings, and adheres to the primary layer well. The primary layer growth of iridium coatings is not influenced by the type of substrates. Morphological characterization indicates smooth and homogeneous surface, the iridium coatings on quartz substrates are smoother than that on niobium substrates.