Iron(III) β-diketonates: CVD precursors for iron oxide film formation

摘要： Within this study, the synthesis of three iron(III) β-diketonate complexes [Fe(β-diketonate)3] (β-diketonate = 2-acetylcyclopentanoate (3a), = 2-acetylcyclohexanoate (3b), = 4,4-dimethyl-1-phenyl pentanedionate (3c)) is described. The synthesis of 3a–c was performed by the reaction of the respective β-diketones with FeCl3 in the ratio of 3:1 in presence of NaOH. TG and DSC studies were carried out under an atmosphere of argon and oxygen, showing that 3b,c partly evaporate during the heating process. PXRD measurements of the as-obtained residues of 3a–c from the TG measurements confirmed the formation of crystalline α-Fe2O3 at 800 °C. Vapor pressure studies confirmed that complexes 3b and 3c show a better volatility (17.3 mbar (3b), 5.4 mbar (3c) at 120 °C) than the iron β-diketonate complexes [Fe(tfa)3] and [Fe(acac)3], respectively [62,63]. CVD studies carried out with 3a,b resulted in the formation of iron oxide thin films in presence of oxygen as reactive gas. However, complex 3c did not result in iron oxide film formation. All received layers were dense and coherent as proven by SEM studies. With metal-organic 3a and 3b, crystalline γ- and α-Fe2O3 layers were obtained at 450 °C, respectively. The XPS studies confirmed the formation of Fe2O3 layers with carbon impurities on the layer surfaces, however, in the layers no carbon could be detected.