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Abstract: Cobalt aluminate (CoAl2O4) thin films were grown in a low-pressure hot wall metal organic chemical vapour deposition (MOCVD) reactor on Si(100) and quartz substrates with a total pressure of 2Torr using bis(η5-cyclopentadienyl)Co(II) [Co(η5-C5H5)2] and aluminium dimethylisopropoxide [AlMe2(O i Pr)] as precursors at 500 and 900°C. Films showed a dark-brown and dark-green colouration, respectively, and after an overnight heat treatment in air at 1200°C, they turned blue. Film microstructure, composition and morphology were investigated in detail by X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS) analyses. Films were polycrystalline and the UV–vis spectra showed three electronic transitions allowed by the spin (540–630nm range) characteristic of Co(II) ions with 3d7 configuration in tetrahedral coordination. SEM micrographs of the heat-treated CoAl2O4 samples revealed the presence of agglomerated crystallites with a highly porous structure. [Copyright &y& Elsevier]

Abstract: Thin films of HfO2 were grown by metal-organic chemical vapour deposition on fused quartz substrates in the temperature range of 400–500 °C using some bis(cyclopentadienyl)bis(alkoxide)hafnium (IV) precursors, namely Cp2Hf(O i Pr)2, [Cp2Hf{OCH(CH3)CH2OCH3}2], [Cp2Hf{OC(CH3)2CH2OCH3}2] and [Cp2Hf{OC(CH2CH3)2CH2OCH3}2]. These complexes, analyzed by nuclear magnetic resonance and thermogravimetric measurements, resulted pure and very stable towards air and moisture. The obtained films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy. The deposits contained hafnium and oxygen in the right stoichiometric ratio with a low carbon contamination and they consisted of monoclinic HfO2 phase (baddeleyite) with a granular surface morphology. [Copyright &y& Elsevier]