Comparison between first- and second-generation praseodymium precursors for the MOCVD synthesis of praseodymium aluminate thin films

Praseodymium aluminum oxide (PrAlO(x)) thin films have been grown by metal organic chemical vapor deposition (MOCVD) using two different multimetal sources consisting of mixtures of aluminum acetylacetonate (Al(acac)(3)) with two praseodymium precursors, namely, the praseodymium hexafluoroacetylacetonate diglyme adduct (Pr(hfa)(3)center dot diglyme) and the praseodymium tetramethylheptanedionate (Pr(tmhd)(3)). Smooth and amorphous films have been deposited on Si(100) substrates. Their chemical composition and microstructure, investigated by EDX measurements and TEM analyses, are deeply affected by the nature of the precursor mixture. Optimal structural and compositional properties are achieved with a Al(acac)(3)-Pr(hfa)(3)center dot diglyme mixture. Annealing procedures at 900 degrees C under an inert ambient atmospher do not affect the film crystallization. Preliminary electrical characterizations indicate a dielectric constant of about 12.