Tiriana Segato

Formation of MgO films by ultrasonic spray pyrolysis from β-diketonate

Abstract Chemical vapor deposition (CVD) from an aerosol generated by ultrasonic atomization was used to grow magnesium oxide films on alumina polycrystalline substrates. The precursor was a solution of magnesium acetylacetonate (Mg(acac) 2 ) in isopropanol. The decomposition of the salt was studied to determine the CVD temperature range. Thermal analysis of the salt by thermogravimetry, differential scanning calorimetry and IR and mass spectrometry enabled a decomposition model of the salt to be determined. Above the melting temperature at 265°C, Mg(acac) 2 is no longer stable. The molecule splits giving, on the one hand, a gaseous organic residue and, on the other, a liquid (MgC 5 H 6 O 2 ) which in turn gives rise to MgO at 450°C. The film presents a smooth microstructure and a highly preferentially oriented structure with the (200) planes parallel to the substrate surface at a deposition temperature of about 400°C. The thickness obtained reaches 10 μm, which represents an effective diffusion barrier on alumina for the deposition of thick films containing alkaline earth elements.